Junction boxes underfloorboards

Hi All,

I went to run the cable for my bathroom supply and discovered the sockets o n this level were fed from the floor above. I had assumed the electrician had run the ring on the same floor. Anyway... the only real option for me now is to cut into the ring rather than doing this at a nearby socket.

So... question is... can I do this using wago connectors under the floorboa rds? I.e. cut into one of the wires and connect the 2 feeds to the bathroom (to extend the ring) to the ends I have just cut with wago connectors -if you see what I mean?

I have done some Googling and seems mixed views and the ones I found were s everal years old so with the regs changing may be out of date.

thanks

Lee.

Reply to
leenowell
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Wagos fitted in a suitable enclosure can be treated as "maintenance-free" but they need to be de-rated per conductor and total per enclosure.

Anyone who is wary of Wagos will likely be especially wary of them in such a situation ... me I like Wagos.

Reply to
Andy Burns

Thanks Andy. What do you mean by "de-rated per conductor and total per enclosure"? I guess it might be to do with me not understanding what maintenance free means. Is it that the wires are not under physical load and could be pulled free at some time into the future? Wouldn't clipping them to the joists stop this?

So... If I use the boxes in the link you sent to out the wires and wagos in I should be fine?

I much prefer wagos to those screw down terminal connectors. I have had much more trouble with them when having to put more than 1 wire in the same fitting.

Reply to
leenowell

A normal maximum current for 2.5mm^2 T&W cable if clipped-direct would be 27A, all the 222- and most of the 773- series Wagos have to be de-rated to 20A when installed as "maintenance free" also the sum of all currents within the single box must not exceed 50A

The exception is the 773-173 Wago, which is normally rated for 41A and de-rated to 32A and 64A total when "maintenance free", so is still OK for a ring circuit.

Installed in an inaccessible location.

Reply to
Andy Burns

Aha. Thanks Andy. Great explanation. So if I use 773's and this box I should be good to go?

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Reply to
leenowell

Provide they're not 773-10x series, then yes.

Reply to
Andy Burns

(in reality many conventional screw terminal junction boxes have been installed in this situation, and they rarely cause problems. There is also some argument about what counts as "inaccessible". Some would argue that under a conventional floor board that can be lifted, would still count as accessible)

Personally I would probably use crimps in some form of enclosure, although generally I like to make terminations at a visible accessory of some sort whenever possible.

I am not immediately aware of any changes that would affect this particular situation. (beyond the relatively recent availability of maintenance free terminations other than crimps)

Reply to
John Rumm

A properly installed screw terminal junction box has significantly higher contact pressure than a wago, so I would expect longer life. Actually, I can't think of any other connection method that has contact pressure as low as a wago, except perhaps a screwit.

I say "accessible" means you can gain access without damaging decorations, fittings, or furnishings in the process. So if you have bare boards, fine, but if you have laid a fitted carpet or interlocking timber floor, then that's not accessible through the top of the floor anymore.

I try to ensure there are no inaccessible connections, but where I had no choice (e.g. joining to existing cable end under the floor), I used a standard circular thermosetting plastic junction box, but soldered the connections afterwards. However, if you aren't skilled in electrical soldering, this isn't suitable for you.

I would not use Wagos in an inaccessible location.

Reply to
Andrew Gabriel

Are you *sure* about that? In the push-in ones used for a single solid connector, there will be a sharp edge on the spring which is digging into the annealed copper wire, I would expect the pressure to be close to the indentation hardness of copper, and maintained by the elasticity of the spring. In a screwed fitting, the contact pressure will initially be the same, but now the load path goes through a brass screw and brass nut (at least in an old-fashioned junction box). Over time, such screws can become loose for a number of reasons.

I've not got around to disassembling a "lever" type WAGO to see how they are made, but as it seems to be an over-centre toggle I suspect there is also an elastic element to help maintain the pressure. I don't know how the average contact pressure compares with a screw but I would still expect the "real" contact areas to be close to the indentation hardness.

Reply to
newshound

Why not a simple junction box? If screw connections are good enough at a socket, why not elsewhere? Under floor boards is considered accessible.

Reply to
Dave Plowman (News)

How often on a well installed ring do you have problems with the screw connections in either the sockets or the CU? Only time I've seen this is when installed by cowboy 'electricians'. Presumably looking for repair work at some time in the future.

Reply to
Dave Plowman (News)

Only if not properly tightened in the first place.

Reply to
Dave Plowman (News)

I'm replacing the 12v halogen lighting in my kitchen, and I've found that many of the 12v screw connections are showing signs of overheating ranging from discoloration to charring and melting.

That's with stranded wire, which would be carrying just over 4 amps (12v, 50w) for long periods (basically all evening, which could be 8 hours in the winter). The install is almost 20 years old, and was a barratts new-build, so it could just be that they weren't tightened down properly to begin with.

Reply to
Caecilius

So laying a fitted carpet or laminate flooring could cause the house wiring to become non compliant?

Reply to
Mike Clarke

Part of the argument for a wago style connection is that its sprung, and hence should not lose contact pressure with thermal cycling and deformation of the cable.

Reply to
John Rumm

On circuits that run close to max thermal load, I have seen screws get lose. The screw position is in effect fixed once tightened, but repeated heating and cooling of the copper will cause it to flatten and creep at the pressure point.

(having said that, I would not personally be concerned about having an under floor screw terminal JB in most circumstances)

Reply to
John Rumm

Yes - I'd seen that too with a 'pro' installation. Don't really understand why, as you'd have to really try to snap one of those screws. Perhaps one of Adam's apprentices doing a homer?

Reply to
Dave Plowman (News)

So why do CUs have screw connections? That is presumably the place where the maximum load occurs.

Reply to
Dave Plowman (News)

I would not consider a carpet a problem.

Reply to
ARW

Had one the other day second fix 3 sockets (he's been with us 3 months and it's only the second time I have worked with him).

He also screwed the faceplates back before I had checked his work. He pulled a face when I made him remove them as I need to check his work. One of them has an earth that had fallen out and one of them had a live that had fallen out. None of the terminals were particularly tight. I gave him some advice on doing the job properly and the next day on a different job all of his sockets were spot on.

But I want to know who has been supervising him for the last 3 months.

Reply to
ARW

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