Half a croissant, on a plate, with a sign in front of it saying '50c'
h a l f b a k e r y
Normal isn't your first language, is it?

idea: add, search, annotate, link, view, overview, recent, by name, random

meta: news, help, about, links, report a problem

account: browse anonymously, or get an account and write.

user:
pass:
register,


                           

Wired backbox

 Neater, cheaper, safer.
  (+7)
(+7) 		  [vote for,
against]

One of the joys of living in the United Shires is our glorious domestic electrical systems. If I were to nit-pick, however, I'd have to say that wiring a new electrical outlet can be a bit of a pain in the arse. The issue is that up to three cables (two ring main plus a spur) have to be terminated at the fascia. Each cable carries three conductors and at least six inches of slack wire is required so that the fascia can be pulled away from the wall for installation/inspection. That's 3x3x6"=54"=4.5ft of wire which has to be folded up inside the backbox. This very often leads to mechanically strained cables which have a tendency to pull out. It looks rubbish too.

The proposed solution is to terminate the conductors within the backbox. The box would contain live, neutral and earth bus bars to which incoming cables would be directly connected. This would eliminate the need for any excess cable. The electrical connection to the fascia could then be via a single three-core fly-lead or, preferably, through an integrated 3-pin plug/socket connector.

Further advantages of this system are that the professional electrician can finish his/her job at first fix (pre-plastering) because the fascias can be easily installed or replaced by the unskilled home owner without isolating the circuit. Furthemore the backbox is automatically earthed, which is commonly overlooked. There would be a small increase in materials cost but this should be easily offset if the electrician doesn't have to return to complete the second fix.

—EnochLives, Apr 14 2015

Please log in.
If you're not logged in, you can see what this page looks like, but you will not be able to add anything.
Short name, e.g., Bob's Coffee
Destination URL. E.g., https://www.coffee.com/
Description (displayed with the short name and URL.)






       This is an excellent idea. I get sick of trying to keep excess cable tidy in the limited space behind a socket. It usually ends up getting jammed in, with only the facia screws providing the necessary compressive force to pack the whole lot down.
—MaxwellBuchanan, Apr 14 2015
   

       There is something unclear here. Many backboxes are steel, and already have screw-holes for the ground/earth wire. There could be some risk installing the specified bus bars inside such boxes. Other backboxes are made of plastic, so the phrase "automatically earthed" needs more details of explanation.
—Vernon, Apr 14 2015
   

       In the UK, steel backboxes are the norm (I'm not sure if they're mandatory - I think not).   

       I don't see why there's a risk having a bus-bar and connections built into a steel backbox.
—MaxwellBuchanan, Apr 14 2015
   

       [MaxwellBuchanan], all you need is for your screwdriver to slip, while tightening a wire to a bus-connector, to see some risk. MY screwdriver slipped once inside a main circuit-breaker box, and there were major sparks flying, and a melted-tip screwdriver, as a result.
—Vernon, Apr 14 2015
   

       This is a really cool idea. You need to consider piggy-backing though, and isolating connections to avoid what [Vernon] is talking about.   

       Quirky.com might pick this one up if it isn't already in the works somewhere.   

       [ ] but leaning towards + : the extra wire is a royal pita.   

       (Properly done) you could add two dedicated types of boxes to the electrician's arsenal: one for simple wall outlets (3 buss + ground) and one for simple switches (3 buss + device-hot + ground), perhaps another with 2 device-hots, for 2-phase DPST switches (this last one could handle all 3 types)   

       But you'd have to go back to the existing method for multi-gizmo boxes with more than one switch or more than one pair of outlets or a couple switches and an outlet, et cetera.   

       //without isolating the circuit// ah, another graduate of the Darwin School of DIY.
—FlyingToaster, Apr 14 2015
   

       //[MaxwellBuchanan], all you need is for your screwdriver to slip, while tightening a wire to a bus- connector, to see some risk. //   

       The power will (should) be off while you're installing the backbox, shirley?
—MaxwellBuchanan, Apr 15 2015
   

       This is actually a good idea - the fascia could just plug into connectors on the backbox and then be screwed down for security.
—hippo, Apr 15 2015
   

       [FlyingToaster], I don't see why any type of wall outlet couldn't be used with this idea, so long as the fascia-to-backbox interface is compatible. If the two are simply connected by a fly-lead then there's no problem. However, I'd prefer to see an insulated plug/socket design so that the fascia can be installed or swapped out without first isolating the circuit. This should be no more hazardous than unplugging an appliance from an outlet. As [Max] points out, of course the power will be off during installation of the backbox itself.
—EnochLives, Apr 15 2015
   

       //As [Max] points out, of course the power will be off during installation// - I have a feeling that professional electricians generally don't turn the power off unless they absolutely have to. The electrician who cut into our house's mains supply and wired in a 50A spur upstream of our consumer unit (fusebox) certainly didn't turn the power off first.
—hippo, Apr 15 2015
   

       OK, yeah, somehow I forgot about the individually switchable circuits for a house or office. The main breaker box, however, often cannot be turned off arbitrarily (with various circuits that MUST stay on) --and sometimes not at all (no switch!), short of external shutdown of the entire place.
—Vernon, Apr 15 2015
   

       [EL] Your raisin debtor for the post is to facilitate initial inspection on an entirely new build home. All well and good: assuming the electrician was competent and didn't cut corners, everything's fine.   

       But the next guy won't be an electrician: he'll just be somebody who wants an extra outlet for his TV, and he might hook it up without a chassis ground, or connect another hot to the common buss (which will blow up the TV but a desklamp would probably continue to work). Maybe the guy after that's a smartass and has just a one conductor cable and runs the common to a waterpipe.   

       If the problem is that tripping a breaker kills power to the entire room, including all outlets and lights, then it wasn't installed properly in the first place.
—FlyingToaster, Apr 15 2015
   

       I don't see the problems here.   

       Installing the backbox would not be fundamentally different from how it is done now: usually, the power will be off at the time. A confident electrician might work on the live system, in which case there's the potential for accidents under either system; the worst that should happen, in that case, is that he trips the circuit breaker.   

       The only difference is that the huge rats-nest junction is moved from the back of the socket/switch to a terminal block inside the backbox. If anything, this new system is safer: a misplaced screwdriver is more likely (in the new system) to short between live and earth, thereby tripping the breaker; in contrast, a screwdriver-slip when wiring a regular socket might leave the electrician as the only path between live and earth (which then makes the sensitivity of the RCD the only safety margin).   

       I'm not a qualified electrician, but I've installed plenty of domestic wiring and I'd prefer the new system to the old.
—MaxwellBuchanan, Apr 15 2015
   


 

back: main index
business  computer  culture  fashion  food  halfbakery  home  other  product  public  science  sport  vehicle