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Ask Slashdot: Wiring Home Furniture?
b1tbkt writes "So it seems that furniture manufacturers have not yet acknowledged the realities of modern life. Kitchen tables could benefit greatly from built-in concealable receptacles. Even more obvious is the need for electrical wiring in couches and coffee tables. I realize that there are safety (fire) concerns but as it stands most families that I know already have power cords for laptops, tables and phones draped over, under and through their couches at any given point. If someone wanted to wire their furniture with AC or some type of standardized LV DC system, what are some dangers to watch for and what, if any, specialized hardware exists for the purpose?"
Google "countertop pop up receptacle" and you'll find many choices.
The engineering problems that present themselves with wiring something that has mechanical components adjacent to or in direct connection to electrical wiring is protecting the cable from being damaged and heat generation. This can mean armored cables or flexible conduits, e-chain (for repetitive motion), or other cable management systems. If you are running any electricity though flammable materials then you need to be concerned about the amperage you pull through it and be mindful of how much it heats up as a regular and peak load. This is very important to be mindful of because a conductor may be rated for a certain amperage but at what temp? Make sure that temp is compatible with the rest of the construction materials involved in your furniture. A larger conductor would mean less heat as it passes an equivalent amount of current to a lower gauge of conductor.
Please elaborate.
*sigh*
There's plenty of powered furniture available, and has been for decades. Those crazy "As Seen On TV" powered folding beds have been around for ages. My new couch has push button electric recliners. Most cars today have powered seats; many of those electrically heated.
The problem I'd have with furniture based power supplies is similar to the problem I have with built in electronics and adapters in vehicles. The lifetime of my furniture and vehicles greatly exceeds the probable lifetime of any consumer electronics power adapter installed in it. I used to work at a high end auto dealership. I installed dozens of iPod adapters (at around $400 a shot. Insanity!) and all of those adapters are worthless to the new generation of i devices that these customers are likely to have. Some of my customers had older vehicles with build in analog cell phones which are now junk that just rides around with them.
Furniture is even worse. Decent furniture should last a lifetime. By putting a consumer electronics power port into a piece of furniture you're basically admitting that it's going to be trash in less than 10 years.
Peter
Downsize DC Today!
They've been making custom powered chairs in the US for a hundred years.
...I made a chair for my mother-in-law once. .. My wife wouldn't let me plug it in.
I happen to work for a furniture store. This feature already exists in a lot of office furniture and, occasionally, in some living room furniture. You will find it more often in an end table because those are usually placed closer to a wall. You will only find it in sofas and chairs, once in a while, if the piece already contains a motorized reclining mechanism. Otherwise, it's just not a practical application to add to those pieces of furniture. Not many shoppers would pay an extra $100 to have a power outlet pre manufactured into their sofa when they can just plug their device directly into the wall, or get a cheap $6 power strip that will do the job. Also, it would not make sense to put these into a coffee table, because coffee tables are usually placed out in the middle of a room and you would have to run a cord across the floor to power the table. Furniture makers do not want to be sued for tripping hazards.
Look at a Plugmold or similar power strip, mount along the front of the couch. (Underneath, for aesthetic reasons.)
Something like this means you're not doing the wiring (if you were qualified, you'd just do it, rather than ask), all you need to do is the mechanical mounting (a few L brackets should do nicely).
Caveat: If you have small children about, this is putting outlets in their reach.
If you want something like this in a coffee table (or if your couch isn't against a wall), have an electrician install a floor outlet in an appropriate spot.
The college where I teach just renovated its science center. I'm very happy with the tabletop power we have in our new physics classroom, and I think the "lessons learned" apply to a kitchen too:
Don't do low-voltage DC. It'll never be the voltage you want, and plug standardization is a nightmare.
Don't put outlets on the top of the table. You'll spill, drop crumbs, and ruin the outlets.
Think about spilled liquids. A lot.
Make sure you can move the table to the other side of the room without cutting wires.
Our new physics lab classroom has long, heavy wooden "butcher block" tables with a top that overhangs the edge by an inch. The outlets are on the front edge of the table, protected from liquids by the overhang. The outlet boxes run to a heavy-duty cable with a male plug on the end: you plug the tables into a recessed floor box.
Sofa - http://www.rothmanfurniture.com/221-11502-4.html
Coffee Tables - http://www.gizmowatch.com/entry/13-high-tech-coffee-tables-for-the-geeks/
Kitchen Table - http://www.sligh.com/home-office-furniture/Westlake-74%22-Dual-Purpose-Electronically-Enabled-Dining-Table-300BA-300/577
For myself, the reason I don't buy furniture with this feature is that nobody offers it. Period. The problem with wall outlets is that they're all too often behind the furniture where people will be needing the power. So I end up with power bars everywhere, often attached permanently to furniture where power's needed.
You'll notice that in office environments all furniture is equipped for power. There's outlets in the floor, and every desk and counter and a lot of fixed tables have power bars along them or underneath them. My office desks at home have cut-outs for power and provision for attaching power bars. And everybody I know asks one question every time they're looking at a house: "Are the circuits 20A?".
Let me ask this: if nobody needs power outlets, why do power strips and boxes sell so well and why do so many homes have so many of them? Answer: because people need outlets that aren't 2-outlet wall boxes, and few people have the skills and the workshop to actually create furniture equipped for what they want so they cobble together what they need from what they can get.
Furniture is even worse. Decent furniture should last a lifetime.
Back in 1987, when I was in college, I bought a fairly cheap couch at JC Penney. Last year, I donated it to charity, as it was a little too worn for me and I didn't have a good spot for it anymore.
Among other things, that couch lived through parties every Saturday night for 4 years, and later had to deal with 70-150 pound dogs using it as a takeoff and landing zone.
Admittedly, all furniture was made better back then, but to get 25 years out of something that cheap says that if anything, your statement about how long furniture lasts can't be emphasized enough.
I had started to babysit a wonderful dog for a friend. The dog liked to sit under my desk when I was working. One day, my Mini wouldn't boot. Dog toothmarks were evident on the low voltage (thank heavens) side of the power block, making it pretty easy to troubleshoot. As he got used to his new surroundings, no further wire chewing, but it could have been a disaster for all concerned. My animal house friends tell me rabbits are the worst, like frustrated EEs with buck teeth...
Anyway, think about animals, little kids, etc. when you're electrifying your furniture.
That's why double-gang divided NEMA boxes and conduit exist. Build the plastic box and conduit into the furniture, ship it with both ends covered by screw-on plates, and leave it up to the end users to wire it as they please (a pair of outlets, a single-gang outlet plus a low-voltage keystone, or whatever).
With a divided double-gang box fed by separate 1/2" conduits, you can run just about anything. At the other end of one conduit, they could put a 15A 120v RV-type "inlet", like this one: http://inverterservicecenter.com/Marinco-150BBIW.RV (if you wanted to wire both gangs for power, instead of using one for ethernet/fiber/whatever, you'd pull out the box divider at the outlet end and feed both from the same conduit). Carlon ENT conduit is perfect for this purpose ( http://www.tnb.com/ps/endeca/index.cgi?a=nav&N=3819+601+3818 ). Worst-case, they could use Hubbell's funky JLOAD single-gang multimedia outlets, which pair a single 120v power outlet with a pair of low-voltage keystones, designed for use with a special box that shields the high-voltage power away from the low-voltage wiring. ( http://www.cesco.com/b2c/product/447768 )
As I recall, in the Mythbusters experiment, the stream broke up after 12-24 inches or so. The "dog on couch" scenario, or "passed out drunk guy" might be within that distance.
So firstly, by tying the hot wire first does that mean there's no return path/path to ground, so any current flow could go anywhere, particularly through the person who's plugging in some equipment?
And does the second part mean not assuming that neutral/ground wires are labeled correctly? And if it is wrong and you connect it anyway what happens?
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