Slashdot Mirror
Solving a Wiring Mess?
FueledByRamen asks: "While trying to run a new power line for a large Sun mass-storage cabinet (located nowhere near a 220 outlet of course), I had the misfortune of needing to pop the lid on my main power distribution panel (previously opened in the late 80s). The whole thing is a rats nest and probably a fire hazard - old-style wiring with broken-down cloth/plastic insulation strewn everywhere, and the utility's incoming power cables have some sort of junction in them that's the size of a 1-liter bottle (on each wire) and is covered in layers of electrical tape. Even (gently) putting the panel back on jiggled something important, and there was a nasty cracking noise and half the breakers blew (all breakers in one of the 2 columns). I've worked with mains voltage in the past (wiring new rooms, installing lighting), but nothing on this scale, both in terms of complexity and potential for death. How do you industrious Slashdot readers go about fixing a mess like this (on a tight budget, no less) without getting a mains-induced glimpse at the great beyond?"
Hire a professional electrition.
Does the name Pavlov ring a bell?
HIRE A PROFESSIONAL
If you have a "Sun Storage Cabinet", you can afford to pay a few thousand bucks to get this taken care of properly. If you can't afford it, then wait until it breaks, and you'll be forced to.
There's also insurance reasons as well. Having someone other than a qualified electrician do the work can void your fire insurance.
along the lines of "you fscking idot don't try that at home". Well, that's totally against the hacker spirit of learning how to do it yourself, hopefully without killing yourself.
I've wired up several additional circuits in my home and my office and it's not that hard. All I needed was a little common sense, a copy of the Ugly's book, and the local home depot. In your case though, if the main drop coming in from the pole is bad, you need to have the power company turn off your service drop so you can replace it.
If the main lines coming in are safely insulated and do not need to be replaced, then what you can do is shut off the main breaker, unscrew all the circuits coming in to the individual breakers, and replace all your house wiring and perhaps all the breakers as well. This is not a job for the faint of heart, but I wouldn't say it's incredibly skill-intensive. Just takes some patience to wire up all that stuff and not slip with your hand/screwdriver and hit the main lugs. If they're exposed where they connect to the main breaker, then you might want to cover them up with cardboard and tape while you're working.
Oh, and don't blame me if you kill yourself. I'm not an electrician - an electrician would tell you to hire an electrician. I'm just telling you where *I* would start.
Suck it up and hire an electrician. Seriously. Yes, those of us who have done lots of electrical work and know not to connect power to ground may feel that it's horribly wrong to pay someone for this, but you really should do it. Even if you know what you're doing, things can always go wrong, and if you're not a licensed electrician you could be opening yourself up to lawsuits by the power company, building code violations, you could lose insurance, etc.
Now, if you want to do your own work inside your house, I would recommend that you get the electrician to install a master lockout switch (different from a master breaker in the panel) between you and the mains supply. Then, play with anything behind that, and you probably won't get in trouble with the power company. You can go re-wire your whole panel yourself, and save some money (getting them to install the lockout switch will be quite cheap comparitively)
There is no sig, there is only Zuul.
Being zapped by A/C at any voltage, let alone 220/440 really is teh suck!
In all seriousness, a wire job as large as you describe will likely have to be permitted with your local government construction office. That means that the work has to be performed by a licensed electrician and it has to be inspected the appropriate government agency afterwards.
If you have that much current flowing in, there are bills to be paid for this.
If you have that much machines running, there's a budget for maintenance.
If your employer tells you to fix it yourself with new wire and duct tape, he either doesn't give a sh*t about you and your safety, or he's completely insane.
Hiring an electrician to install some lamp wiring is stupid and overkill if someone in-house can do it, but playing in an electric box isn't.
For the price it would cost you to have it done by a professional
1. you will cut the downtime,
2. have a fully secured panel (and certified)
3. If it catches on fire you won't have problem with insurance claims since it was certified (whereas if you mess around in this yourself without the credentials, you could run in a PILE and I do mean a PILE of problems). This point alone should make a perfect argumentation to any "managers".
4. Your paycheck isn't worth you life, especially if you have to turn around to slashdot for advice.
5. If you are so much on a tight budget, sell off one machine to pay for the contractor, or try to find someone that would do it for cheap, still, you'll have to pay for the material and it doesn't come cheap. I don't beleive in "tight budgets" for critical things like this, again, if you can afford having this many machines running, you can afford to support them, if they are all put to use, surely you are generating revenues, if they aren't , they can be sold.
6. See point #4 as a personnal advice.
I'd be really scared to work at some company that couldn't afford an electrician for a job like this, if they are so tight, chances are your paycheck will eventually bounce, so risking that much for that little...
--- Metamoderating abusive downgraders since my 300th post.
Not only is it dangerous and lethal, not to mention analog... its ILLEGAL in most places for you to do the work unless you're a licensed electrician (some exceptions for certain 120vac work). Heck... a lot of places require you to have a Low Voltage certification to run cat5......
For home, who cares,,, for business: follow the rules.
Hire a professional. A real professional. It won't necessarily "be cheap" but it will be safe. When the powers that be balk, ask them which would be "cheaper", getting this fixed and staying operational, or having the whole thing go *POOF* and take the location out of service and still have to get it fixed.
If you are the unlucky person that has to fix it, then find the main that feeds that panel and TURN IT OFF.
Don't even think about trying to fix this problem while it is hot. Not unless you've got a deathwish and, if you have any family you care about, a great big life insurance policy that will still pay out after acts of stupidity.
I've worked around a few power systems, and the one thing above all else, give that electrical panel LOTS OF RESPECT. Always assume a circuit is hot, even if "you KNOW you turned it off earlier". Always leave a flag on the circuit that you turned off so that others know it is off on purpose, especially if you have to turn off a main to kill power to that panel. Always remember SAFETY FIRST, even when your working on a "dead" panel. If you have insulated tools, good -- use them. If you have heavy duty insulated gloves -- use them. Never work alone -- always have somebody around that is aware of what your doing and that can check on you from time to time, or better yet, keep you in sight. They don't have to help you work on the circuits, but if something goes horribly wrong and you get zapped, that person can call 911 and get you help.
. 62,400 repetitions make one truth -- Brave New World, Aldous Huxley
I bought an old house with old style wiring last year. The wiring was a mess. I had an electrician come in and fix a few things but it would have cost too much to rewire the whole house. I bought a copy of this book (it's well worth the price.) I spent about a 6 months reading it and working up the guts to start. I got a permit just a few weeks ago. Once you do a little bit, you realize it is not that big of a deal. Any geek should be able to figure it out and avoid the obvious mistakes. Just research it for a while first. Actually, I found the worst thing about it is that it is very physically demanding (and I am in very good shape.)
By the time I am done, it will probably only cost about $700 - $1000 (permit and inspection cost account for about $300 of that where I live.)
Don't resign. A worker can notify his supervisor that due to what the worker believes that doing the task placed before them will put them in imminent danger, he can refuse to do that task. The worker then needs to fill out a form or two and contact the Occupational Safety & Health Administration. The worker cannot be disciplined for refusing to work in a dangerous situation.
I've felt both a time or two (accidentally). 110 is really more of a tickle and certainly won't kill you.
You've got to be respectful of it but with 110 I didn't even realize I was being shocked until well after the fact.
Dude, 110 volts is most certainly enough to kill. True, most of us have been "tingled" by 110/115 a few times, and didn't die... all that proves is that we were lucky on those occassions.
For an interesting discussion of why low voltages *can* be deadly, see this page.
The bottom line is, lower voltages tend to be "safer" due to the resistance of your body, and the fact that low voltage power sources also usually have a fairly low current capacity. But try wetting your hands and grabbing the leads from an arc welder set on 200+ amps sometime, if you don't think low voltage can f#@k you up.
// TODO: Insert Cool Sig
Not to mention being able to slap you with lawsuits for damages, as well as building code violations if something goes wrong.
Electricity is not a toy (as I have heard, many times, because my father was trained as an electrician).
This is not a sig.
"First thing to do is SHUT OFF THE POWER AND INSURE IT WILL NOT BE TURNED BACK ON UNTIL YOU ARE DONE!!!"
This is extremely good advice.* Professional electricians will put a little warning sign over any breakers, switches, etc. that are shut off that says essentially, "if you turn on power here, you'll kill someone." Make sure you have one.
That said, I too think this is a very good way to add yourself to the next Darwin Awards.
*Ignoring the goofup with "insure" used rather than "ensure", but that's not a *big* deal.
Turning the power off, even if you type about it in ALL CAPS, is not enough.
A big detail is that you must discharge any capacitors. THEY will kill you, even with the power off, and sometimes, they are not easy to find.
Don't do this, sheesh, it doesn't sound like a job worth dying from, now, does it.
It's the friggin' *law* in most jurisdictions to get a licensed electrician to do this work, and for very good reason.
In a facility I ran years ago I smelled smoke in our main distribution panel. Called our electrician and he *immediately* turned white, got out of there dragging me with him, closing the door to the small power distribution room behind him and immediately went to the building's main distribution breakers next to the elevator shaft on the bottom floor and turned off all power to our floor.
Why? He'd seen the insulation bubbling on the aluminum power cable that was connected to the main copper bus for the breaker box.
It had been connected without anti-oxidation gel and the aluminum had oxidized increasing resistance to the point where the insulation was near burning.
He told me that an electrician had been killed earlier in the year when a suburban shopping mall's main panel blew up as he was inspecting it, after having been called in during the wee hours of the night by the fire department after a report of smoke had been called in.
If the original poster's company doesn't own the building then the landlord can be forced to pay, just call in the friggin' city electrical inspector and after he shits his pants your building owner will be paying to rewire the box ASAP.
I rewired my whole house from the power pole down (was 40s era ungrounded knob and tube with 30 amp service) so it can be done but some things will make it easier.
First, find an electrician friend or at least an electrician who is DIY friendly and get a professional opinion. If the insulation in the panel is bad it may be bad in the walls as well. You may not want to know.
While you can do the research and learning yourself, a pro will quickly spot certain gotchas like aluminum wiring without the proper anti-corrosion connectors or grease.
They will also likely spot other things you would probably miss such as certain Federal Pacific Electric panels and breakers (http://www.inspect-ny.com/fpe/sec1982.htm).
In my case I knew plenty about electricity in general but hiring a friend for a few hours to review the project and teach me the tricks really helped speed the job. He was also able to review the codes. Again, basic electricity wasn't the problem but my friend was intimate with all the issues like where GFCIs are required, required height of outlets, how many are required per wall, allowed location and hole sizes in floor joists, locations where conduit/BX is and is not required.
A lot of the codes sound arbitrary and to a certain extent they are but before dismissing them as silly remember that they represent the accumulated wisdom from the fires, electrocutions, etc. in the past. Building codes are all written in blood.
A pro can show you good tricks. For example, throw away the stupid paper template that comes with the retrofit junction boxes and simply hold a torpedo level against the box, use a tape to measure the proper height and pencil around the box then cut.
Also, before locating a box take a piece of straight coat-hanger wire, chuck it into a drill, and drill it through the baseboard or ceiling wherever you want to locate the box. Then crawl under the house or into the attic and the wire will give you the exact location so you can check for obstructions and you can drill the holes in the right place. Much better than trying to measure plus coathangers are free and the tiny hole is easily filled with a dab of spackle.
If you do get into major rewiring I recommend a few things:
1. Use 20 amp wiring - the material cost is very slightly higher but labor isn't. You have extra capacity and lower resistance losses.
2. More breakers - OK, I went a bit overboard with well over 20 breakers in a 1200 square foot house but running every kitchen outlet to its own breaker cost me very little in time or money and I have no problem running the microwave, coffee maker, waffle maker, toaster along with the fridge and dishwasher.
3. Outlets everywhere. I added outlets in every closet - they are great for powering chargers, adding a burglar alarm, etc. Add them where you might add appliances - I'm finally getting a garage door opener but the install will be easy since the outlet is already in place. While I was up in the attic I added an outlet under the eaves - handy every Christmas. I increased the number ouf outlets 3-4 fold and have used every one.
4. Run 240 to the garage - you will eventually want to run a small welder and even if not you might want to use it for an illegal backfeed from your generator in a blackout (just be sure to kill the main breaker first).
Upgrading to a solid over-engineered electrical system wasn't like getting a new computer or other toy - it was more like finally getting a pebble out of my shoe (no more blown fuses, no more sticking a three prong adapter on the extension cord then tossing it out the bathroom window to be able to mow the back lawn...) It's work but the result is nice.
~~~~~~~
"You are not remembered for doing what is expected of you." - Atul Chitnis
I am a lifelong blue collar guy, gardening, landscaping and construction. I have worked a fair amount part time with electricians. Do it yourself electrical work is ok for outlets, ceiling fans, etc, if you are smart with your hands.
But you need to stay FAR away from the Main Panel unless you are knowledgeable. That thing is dangerous, there ARE many non obvious mistakes you can make if you are not an experienced electrician. You can hurt yourself, burn down the building, damage stuff attached to the electrical system, and if you do something REAL IGNORANT, it is possible (unlikely) you can hurt someone working for the power company outside the house.
This is coming from a Gung Ho!!! Do It Yourselfer/ Shade Tree Mechanic
HenryJamesFeltus.com
Don't flag, lock it.
Get a keyed lock with one key.
Turn it off, lock it out, carry the key while you work.
That is the ONLY way to do it.
Don't have one of those? THAT'S BECAUSE YOU'RE NOT FARKIN' QUALIFIED TO DO THE WORK!
If you have not had the correct training, you CAN NOT safely lock out equipment. Sure. You locked it out. You stuck your wiggy in the wall socket to make sure you got a buzz. You tested each terminal and they were all dead. You started stripping wires. You reached way into the cabinet to unscrew some terminals in the back. It got dark and the building's outside lighting circuit turned on. Guess what? Someone ran the lighting circuit through the box.
oopsie.
You don't know what you're doing. Neither does the person who "told you how" to do this safely. Hire a professional.
"Reality is that which, when you stop believing in it, it doesn't go away." - Philip K. Dick
Hey, always nice to get the proper answer from the horse's mouth (i.e. the article author).
Seeing as how you ARE from the US, I'd simply call it "service". At least, that's what your local power company would call it:
Transmission = the 60kV and higher network that connects substations and switching stations.
Primary distribution = the 12kV to 25kV (sometimes up to 35kV, sometimes down 4kV) network leaving a substation.
Secondary distribution = the 120V/240V (sometimes 480V) network on the "low" side of distribution transformers (which will look like the 10-gallon drums you see mounted on every N-th pole if you have overhead distribution in your neighborhood).
Service = the drop from a point on the secondary distribution network to the customer.
Slashdot is entertaining like pro wrestling is entertaining
Its been said already, but it cant be said too much.
I just wired a major remodel of our home, myself, and understand what I'm doing running a wirign circuit.. but I hired a pro to wire the main panel and subpanel and especially to hook it up to the feed, and to check my work. Doing this wrong can kill you. It can kill someone else. And "wrong" can be something simple and easy to overlook that you wouldn't think matters.
Hire a pro to come look at it, immediately. It aint worth the potential tragedy and legal issues if something goes wrong.
It's a great idea to call in an inspector periodically. Even the best-wired distribution box will eventually go bad and possibly cause a fire.
Why? Stuff expands when it is heated. Your connections are continually undergoing varying stresses depending on the current. When a connection works itself slightly loose, the resistance increases and the process speeds up.
Where I work, we have the local power service come in and take pictures of our distribution boxes with an infrared camera. That's a great way of pinpointing connections that are heating up too much.
This is the reason a computer can stop working, too...sometimes you can just pop the lid, wiggle everything and cinch it down, and it works.
...
Lots of comments here mostly ranging from the "you're an idiot" to "get a pro". No need to restate the obvious, so I'll just add my personal notes:
First, if you can, get a pro instead. That being said, there's a lot of good you can usually do without a pro's help. Playing with mains is not the thing to do if you're an armchair electrician like myself. Those sorts of things I usually leave to them. You can, however, do work on the non-mains wiring without seriously endangering yourself. I managed to wire my entire house to the box after the mains were properly installed and am quite living to talk about it.
Here's the problem with mains: They're either a) not breakered if you're past the mains breaker, or b) the mains breaker is too high to stop anything from frying you where you stand. One thing you definately want to avoid besides touching the mains is cutting them. If you cut it on the service side of the mains breakers, oftentimes they're not breakered back down the line. The line back to the transformer will glow very pretty red and probably catch on fire, depending on whether or not the transformer blows up right away or later. It can be impressive, I don't recommend it.
Work with one hand in the box when attaching wires to/from the breakers themselves. One hand behind the back will keep a path from going across your heart. Avoid standing in kiddie pools while working on the box. Strip the wires only right before you are going to hook them into the breakers, that way you don't accidentally make contact early. Shut off everything you can before playing in the box. If you can't shut off the mains, have a person near you to whack you away with a board or call 911. If you can shut of the mains, you're reasonably protected, just use a voltmeter to make sure.
Common sense prevails here. If it makes you shaky and nervous to get in the box, get a pro. Otherwise, watch yourself and keep your head on, and you can do some of the work without harm.
Blog,Twitter
Couple of notes from an amateur electrician:
"I would suggest buying several different colors to help keep things straight in the next step."
Um, there are color codes for a reason:
black (for sure), red (if 220), orange (if 3-phase, then it's the high leg) are all hot
white - neutral
no insulation or green - ground
"SHUT OFF THE POWER AND INSURE IT WILL NOT BE TURNED BACK ON UNTIL YOU ARE DONE!!!"
And if possible, pull the meter. Seriously. Have the power company pull the meter, do your work with the meter pulled, then have the power company put the meter back in. However, the power company will probably want to see a permit, and that will take a licensed electrician in most cases, so that may not be an option.
Also...if you are terminating aluminum connections, make sure to use anti-oxidant goop on the terminations and torque them only to the recommended specs. Don't have a torque wrench? Call an electrician. Al is nasty if not terminated correctly. In fact, that goes for all connections. If at possible, beg or borrow a torque wrench so that you can terminate connections to the proper specifications. Note that that only applies to main connections, not branch circuits.
To start off, I am an electrician.
.5 of an amp can kill you and anything higher than about 3 amps will allow the mortuary to not have to charge your widow for your cremation. Just supply the urn, ma'am.
Hire a professional, period. It may very well save your life.
Anything higher than about
I'm pretty sure that the budget will get modified to accommodate your needs when you tell your boss that the new system cannot be installed due to the shoddy condition of the mains box.
If you are forced to work on the box yourself, immediately contact OSHA, your local Fire Marshal and your local State or County Building Inspector.
They should be able to convince your employer that it would be in their best interest to have the electrical system repaired by a Licensed-Bonded commercial electrician.
Well, let's see - you can give the current a 1000ohm path from your hand, through your body, and out your foot, or you can give the current a 100 ohm path through your four fingers, palm, thumb and wrist, and lose your hand.
Instead of having a chance at reconstructing a lot of body, you have no hand - it can't be reconstructed at that point. But you won't have to reconstruct your other body parts.
In short, you NEVER, EVER, EVER ground yourself when working on high voltages. IIRC, anything over 60 volts is considered 'high voltage'.
The grounding straps you use for electronics have a built in resistor of 1Meg Ohm or so, but the insulation break down resistance is low, so it will act as a straight route to ground in the presence of high voltage - not good. You only use a certified grounding wire when working with non-powered equipment.
-Adam
I'm not an electrician, but I've done a lot of my own electrical work, and I've put in a good bit of study to make sure I'm doing it right.
The problem you describe sounds like a major one, and you'll need to hire an electrician. It's what I would do, and I feel comfortable wiring anything in my house this side of the main breaker. Fact is, you may need to replace the whole panel, and that requires coordination with the utility company to pull your meter, and you'll probably need a new service entrance. That's just not a handyman job.
That said, the "old wiring" may not be as bad as it looks. Get a professional opinion, of course. There are a few kinds of old wire with paper/cloth insulation. The oldest Romex has a shellacked paper or cloth outer wrapper and rubber insulation on the wires. The rubber becomes brittle with age, and should probably be replaced to avoid shorts and arcs. Later Romex still had the shellacked paper, or asphalted paper, but the wires have modern thermoplastic insulation. The outer wrapping of the cable can get brittle and very messy, but the insulation holds up okay. As long as Romex of that era isn't totally disintegrating, it's not an issue to panic over, as the thermoplastic insulation is durable.
If you see any aluminum wires in your breaker panel other than the service entrance or a heavy-gauge subfeed, have your electrician rewire the house ASAP. Aluminum wire for branch circuits is a house fire waiting to happen, even with "aluminum rated" outlets.
If you're going to do any major electrical work, go down to Town Hall and talk with the building inspector. They're usually quite friendly and helpful. Their job is to help you do things right and follow the codes. The codes are there to keep you from making mistakes others have already made, and to keep you from doing something foolish and unsafe. If you're polite and friendly, your inspector will probably be glad to sit with you for a while and give you pointers on how to do the job right.
Of course, it helps if you already know how to do it right. The National Electrical Code can be hard to track down; a lot of libraries don't seem to carry it, and those that do classify it as a reference work, so you can't borrow it. Luckily, thanks to a recent Supreme Court decision, building codes which are enacted into law lose any copyright protection, so you can go ahead and photocopy away.
You may also find other helpful books. I'm particularly fond of Wiring Simplified, a book that covers most common household wiring tasks and includes Code references.
When sparks start shooting out of things, though... that's time to call the pros.
I work for an electrical contractor as a draftsman so here's a little info.
We are open shop so I say don't call any IBEW shops. They aren't any better, but they'll cost you more (IMHO).
Just make sure they are licensed (wether it's contractor or electrician.) and COMPETANT. Licensing varies State by State and even by local jurisdictions. Some states the contractor is licensed (California) and some only have licensed electricians w/o contractor licensing (Texas).
Electrical Conductor Color Coding:
120/240V (1 or 3 phase) or 208/120V (3 phase):
Phase A - Black
Phase B - Red
Phase C - Blue (3 Phase only)
Neutral - White
480/277V:
Phase A - Brown
Phase B - Orange
Phase C - Yellow
Neutral - Grey
(Remember B.O.Y.)
Ground is always Green and is voltage independant.
If it isn't marked, be careful. "Phase Tape" may have come off. Most wire sizes 4 gauge and larger (smaller numbers) is generally always black. "Phase Tape" (colored electrical tape) is used to mark the phases as noted above.
The panel SHOULD be marked as to what it is. Usual voltages are:
120/240V 1 Phase, 3 Wire (Common Residential)
120/240V 3 Phase, 4 Wire (Be CAREFUL. You can have a stinger leg @ 208V. By code it should be Phase B and the panel should be marked).
208/120V 3 Phase, 4 Wire (Common Commerical [and mutli-tenant Residential])
"High Voltage"
480/277V 3 Phase, 4 Wire (Common Commercial/Industrial)
These are common system we work with, and of course is not exhaustive.
A special note, if the system is using shared neutrals (you can share 1 neutral with up to the number of phases. i.e. 3 circuits on a 3 phase system as long as they are seperate phases [1 from each Phase (A-B-C)] and 2 circuits on a 1 phase system) make sure to turn off the power to all off the circuits using a neutral before opening it. We had to replace 6 UPSes when an electrician opened up a neatral on a 3 phase system. And if circuits are being used, there IS power on the neutral. It can very based on the circuit. Check it with a meter to ground to show you the voltage.
There are also further color codings if you are using Romex style wiring. The outter jacket on new Romex denotes the wire gauge size. The only one I can think of is yellow and I believe it's 12 ga.
New MC cables (it's like flex, but from the factory and you can't change the wire insde of it) is also color coded to the wires inside.
The version of the National Electric Code you will need to comply with will depend on the Authority Having Jurisdiction. The AHJ will be your local building inspector. They have the final say so on what happens. The most current NEC is the 2002 NEC, but many AHJs are still using 1999 as they haven't made their local tweaks. For example, CA takes the NEC and creates the California Electrical Code. It's basically the same. We always design off of the NEC anyways.
Little notes:
A standard circuit breaker should have no more than 80% of it's rating applied to it. 20 Amp circuit breaker should have no more than 16 Amps connected to it. A fuse can be loaded to 100% of it's rating.
The overcurrent protection (circuit breaker or fuse) shouldn't be rated less than the wire that is connected to it. But you can put larger wire than the breaker (as long as the wire physically fits the lug.) I.e. you can put wire rated at 200 Amps on a 100 Amp breaker, but you can't put wire rated at 100 Amps on a 200 Amp breaker.
To the O.P.: I would definately contact a qualified person. If the company you work for doesn't own the building, then most likely you HAVE to have a licensed contractor or electrician. It sounds like you need some major wiring work done or at the least checked out.
Most Americans who aren't professional electricians don't have much experience working with the 220, except maybe plugging in their driers. Therefore, people don't treat it with the same respect that they should, as evidenced by FueledByRamen who needs to back away from his box slowly and call a professional electrician.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Ok folks
I've wired power panels in residential situations. I have NO unreasonable fear of electricity. I used to work professionally in HEAVY duty power electronics (Multiple 10s of KW UPS systems). I've worked on 400Hz AC Power supplies (Hurts more than the 60Hz stuff). I've been zapped by 220 3phase more times than I care to remember, and even 400 volts DC. I used to have lockout tags. At one point I even used to do wiring that required an electrician to sign off on my work, and never had to change anything
You know what I would do in this situation?
CALL AN ELECTRCIAN
Does that sum it up?
-- 73 de KG2V For the Children - RKBA! "You are what you do when it counts" - the Masso
Haha, right. Thanks for providing false information. And thanks to the Slashdot morons who modded this up.
Of course the law if different in different areas, but almost all allow you to work on your own electrical stuff.
Just call the power company and have them shut off the mains. Then you can do whatever the fuck you want. When done you will need to have an inspection done (usually by a city official, but could be power company). Then you're done.
Morons, the lot of you.
And while we're at it, you've got to also consider P=IV (although in this case the P is quite massive). If the voltage increases, the current must decrease in order to maintain the same power. This is the reason a stun gun won't kill you; it can only pump out X watts.
***
Radio Shack. You've got questions...we've got blank stares(TM).
Unfortunate, past a certain stage, you don't bounce: if the current causes your muscles to contract and clamp on to a conductor. A couple of years ago, an electrician at UMich.edu was working on a 480V (440V?) circuit that's standard in the new physics building. He went against protocol by working alone: protocol required he have a partner. He died.
Basically, don't fsck with the stuff unless you know what you're doing.
Yeah: what he said. It'd be a hell of an auto-LART.
This is a tautology.
Actualy what you describe is an OSHA requirement. It's called Lockout Tagout. One small bit of info on the hasp. Never put a lock in the last hole. Put another hasp in it so anyone else joining the project also has a place for his lock and tag. The power can not be restored until everyone has removed their respective lock and tag.
The truth shall set you free!
First: This is important. You want to play with the main breaker box in a serious way, Call the power company, inform them that you need to work on the breaker box in your building. Ask them to come out and switch off the mains at the street! Verify that this was done using a simple volt meter. (you can get a $20 one at radio shack.) A simpler way of doing this is to check to see that a previously working light or outlet is now depowered. To be thorough however you should use the volt meter to check the output of each of the breakers.
Second: Inspect the wiring for Blue/White vs Black/white pairs. Blue and White is the old stuff, and is damn near garaunteed to fail if you try to reuse it. General advice is to give up on any Blue/White pairs if you have any reasonable chance of rewiring those circuits.
Third: Verify that all circuits are hanging off from the correct size breakers. 12 Gague wire can handle up to 20 Amps, 14 Gauge can handle 15 Amps, and 16 gague can handle 10 Amps. Anything wires smaller than that Should Not Be used at the breaker Box You can use a breaker that is rated for a lower amperage than the wire can handle, but not higher. I.E. You can use a 10 amp breaker with 12,14, or 16 gague wire, but a 20 amp breaker can only be used with 12 gauge wire.
Fourth: The mains from the street are 3 major cables. These are different than the wires that go to "normal" outlets and lights in your house. The normal outlets and lights in your house use 1 of the two mains from the street and ground. A 220 Outlet uses both of the mains from the street and ground. Thus a 220 outlet has 220 volts, or 2 110 volt circuits 180 dgrees out of phase for those amatuer electricians in the crowd. What you need in order to wire up 220 outlets are the usual gague wire, but the breaker is different. For a "normal" circuit, only one breaker is neaded because only one of the three wires is "hot" meaning that it sources power. In 220 outlets, two of the wires are "hot". This means that both hot wires need to be connected to a breaker. The same rules for cable sizes applies as before. When running 220, you must use a double breaker of the correct size for your wire. What this does is if one of the two circuits blows the breaker, the breaker will disconnect both "hot" wires, rendering the circuit completely dead.
Fifth: Although it may seem like a good idea, do not use a breaker with any wire that is not "hot" You do not ever want the circumstance where your "hot" wire is powered, but the ground wires are disconnected by a breaker.
Sixth: All of the wiring into the breaker box should be exactly the length needed. No excess wire should be stored in the box. All cables entering the box should be clamped securely in place. (a hardware store will have the clamps for use with just about any breaker box and cable.) The wires in the breaker box should all have their shielding completely intact. Replace any wires for which the shielding is missing or damaged. All wires should be mounted into the breakers such that no unshielded part of the wire is exposed. If it is, disconnect the wire, and trim it such that only shielded portions of the wire are exposed. As a general rule, the breakers should be wired to one and only one wire each. If you do not have enough breakers for all of your devices I strongly recommend buying a bigger breaker box. If you must wire more than one wire to any given breaker, that breakers size should be determined by the size of the smallest wire being connected to it. If you have a brekaer with a 12 gauge and a 16 gauge wire connected, then the breaker should be a 10 amp breaker.
Once you are done, use a standard issue voltmeter to verify that there is no conductivity between any circuits when the breakers are all in the off position. Then, switch the breakers one by one to the on position and make sure
I wish I had a good sig, but all the good ones are copyrighted
In most residential wiring the thing you use to turn the power off to the main circuit box is the meter. You remove the meter, which by the way has a seal on it stamped by the power company, and this removes power from the two phases coming into the house. This is the only safe way to work on a main circuit panel. I do know know what kind of regualations there are where you live but in some places you can remove your own meter but not put it back. In other places you can not remove your own meter.
The reasoning behind laws in regards to not removing your own meter would probably be economic since that would be how you would steal electricy.
One point of contention I have about home wiring is the type of electrical box used to house switches, outlets, and various other junctions of wires. I am curious if anyone else agrees or disagrees with my thoughts on this matter.
The contention I have is this. I think metal boxes are much safer than plastic boxes. My reasoning is as follows.
1. With a metal box which is properly attached to the safety ground you have a situation where a live wire coming loose inside the box and hitting the box will immediately trip a circuit breaker.
2. If the live wire does not come loose but only gets flakey and hot and starts to burn your metal box will not burn along with it. It will still trip the breaker when the wire has burned enough to break free and hit the side of the box.
3. It is obvious to me that plastic boxes will not trip a breaker if a wire gets loose inside them.
4. A plastic box with a hot wire will actually burn and help in the process of burning down your house.
5. I think the only reason electricians started using plastic boxes was because there were cheaper than metal boxes.
6 Saying a plastic box is better because it insulates you and the wires inside from grounding out against the box implies total ignorance of one of the the purposes of a safety ground. It also allows shoddy wiring to go unnoticed longer.
Those are my reasons, what do you think?
dzimmerm
Jumping to correct solutions slowly is better than jumping to incorrect solutions quickly.
BSEE, sometimes a C++, assembler, etc. programmer, hw engineer, auto mechanic, audio engineer, and the list goes happily on. :)
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About the panel- the large connections you described on the large wires are very common. They are "bugs" or taps, possibly not insulated other than by the tape. Occasionally sharp corners cut the tape- not good! Very large wire is measured in "MCM" sizes- 500 MCM can carry 500 amps, for ex. I've worked with electricians where we "bugged" onto 750 MCM live. It was only 120/208, but any short would have made a nasty show. I've welded at up to 225 amps and that makes quite a show. Shorting a 750 MCM feed would draw well over 2000 amps for a brief time, and it's quite possibly not fused/breakered if it comes directly off of an Electric Utility transformer. (yes- YIKES!!!) There are high voltage side fuses in the utility lines (at 4,160, 13,600, 36,000 volts, etc.) but they don't usually blow before the transformer blows up (often very explosively.)
The "bugs" are basically a lump of copper with holes for the wire to go in and perpendicular Allen set screws to clamp the wire. There are nice insulated ones available now.
Most larger panels in commercial buildings are 3-phase - 120/208 if supporting device circuits. You get 120 from 1 phase leg to neutral, and 208 across phases.
If the main neutral is loose, phase leg voltages can and will go nuts, lights and equipment will be blown, breakers can blow, etc.
The anti-corrosion compound should be used on large copper stuff too.
New Romex colors (from above comment):
white = 14 Gauge (15 amp circuit)
yellow = 12 Ga. (20 amp circuit)
orange = 10 Ga. (30 amp circuit)
Don't know beyond that- 8 Ga. is usually black jacketed.
The human body and heart has a peculiar sensitivity- DC current between 25 mA and 300 mA can cause VF (ventricular fibrillation) - where the heart flutters/quivers and is not pumping. The electrical circuits are all out of sync and you die. Defibrillators discharge a big jolt which does a really hard reset on the heart sync. circuits. (really!) Sensitivity to the current range varies person to person of course. Less current doesn't affect the heart, and more than 300 mA can stop the heart like a defib. but won't kill you if you get off of the current.
I don't know about AC and VF, but I imagine it applies also.
"110" is usually at least 120- I get 125 most days (measure it!). "220" is really close to 250. Stove gets hotter, clothes dry faster, bulbs brighter (and last only a few months), electric company sells more KW!
Oh, and yes, HIRE AN ELECTRICIAN!!!!
I can only speak for the parts of the USA where I have lived and worked on house wiring. That would be Michigan and Ohio.
Most places have a copper pole driven into the ground below where the electrical meter is on the outside of the house. We also have a neutral wire coming in from the pole here in Ohio. That neutral wire is connected to the earth ground as well outside under the meter. I have seen the water supply system also tied into this neutral wire but with the advent of plastic supply lines that form of ground is also suspect.
I think what some folks fail to realize is the safety ground does not need to be a seperate ground from the neutral wire. It just needs to be a seperate wire going from the fuse/breaker box to the outlets and other junction and switch boxes. The reason it is a safety ground is that it has a less resistive path to ground than the neutral wire. This is because the neutral wire is dropping voltage due to its resistance to current flow. The safety ground is not dropping voltage across its length since there is not, or should not be, any current flowing through it. This lack of current flow means that the voltage at the safety ground is as close to zero in relationship to any hot phases being supplied as possible. This took me some thought and a few explanations to realize.
If you only relied on the neutral wire for a safety ground then the apparent ground voltage state would change as the load on the wire increased. It does not really matter if the safety ground is a seperate earth ground as long it is a seperate wire that is not carrying load current between the fuse/breaker box and the outlet box.
In the places I have done electrical work the standard is that 12 gauge wire can handle 20 amps of current safely. This gauge wire is fused with 20 amp breakers or fuses. 14 gauge wire is capable of handling up to 15 amps safely and is fused with 15 amp breakers or fuses. If you want to go up to 30 amps then you need to use 10 gauge wire and corresponding fuses and breakers.
I would disagree about wires melting only when too much current flows through them. That can be the case, of course, but there is also the situation where the wires have corroded and then the corrosion heats up due to its higher resistance and that in turn heats up the wire and or terminal. This will mean less power is being delivered to your appliance or light. That power is instead heating up a bad connection. It is these situations that a metal box can contain a fire where a plastic one will not.
Another issue is that some folks are not carefull when they strip wire. Most wires used for residential use are solid copper or aluminum. If the wires are stripped with a cutting tool a small nick or series of nicks can be made to the wire. This will cause the wire to break at that point. If the wire does not break it can be weakened and have a higher resistance at that point. This is the reaon it is wise to use a correct gauge wire stripper when taking the insulation off the wire so as to avoid nicking the wire when you remove the insulation.
In a previous comment someone said that their plastic box smelled bad and warned them that something was wrong. What if they had not been home when it smelled bad?
IMO metal boxes are a small price to pay for containing fire and providing a safety grounded enclosure.
dzimmerm
Jumping to correct solutions slowly is better than jumping to incorrect solutions quickly.