Lighting Circuit Nuetrals in Domestic Light Switches

[Simonslimline]

Down-lights have been installed without using strain relief or MF JB's for years without problems surely.

 

[DPG]

Down-lights have been installed without using strain relief or MF JB's for years without problems surely.

So have lots of things, doesn't make it right though. And don't have to be MF when accessible, but still should have strain relief.

The IEE Wiring Regulations state that terminals shall not be subject to undue stress,
i.e. taking weight of cables or fittings.
Currently a high proportion of Junction Boxes are installed behind Downlighters or
decorative light fittings, where moving the Junction Box in to position after wiring
could cause stress on the terminations.

 

[IzzyS]

It's more the juggling around and moving things around when the boxes are pushed up into the ceiling though. Daz

Is that why sockets, switches and cooker control units all have built-in cable restraints? Lots of juggling around especially with 6 & 10 mm cables, and quite likely that a "Part P" decorator will pull them free to tuck the wallpaper into the box or paint round them.

Maybe if the JB is in an accessible place where someone may trip over it, such as a loft then I agree the terminations could conceivably end up under some undue strain. I feel this is another of those regs designed to sell more expensive new products.

Having said all that, I usually use wago boxes or hager MF JBs as they're quicker to wire.

 

[Jay Sparks]

It's more the juggling around and moving things around when the boxes are pushed up into the ceiling though. Daz

ok, so what about the terminal block on top of the down light. Is that classed as inaccessible.
or If they have a transformer. Both of these would have the same problem as you described with the jb.
Jay

 

[DPG]

ok, so what about the terminal block on top of the down light. Is that classed as inaccessible.
or If they have a transformer. Both of these would have the same problem as you described with the jb.
Jay

Possibly so, but the regs state strain relief on JBs that are not fixed, as above. Daz

 

[Simonslimline]

So have lots of things, doesn't make it right though. And don't have to be MF when accessible, but still should have strain relief.

The IEE Wiring Regulations state that terminals shall not be subject to undue stress,
i.e. taking weight of cables or fittings.
Currently a high proportion of Junction Boxes are installed behind Downlighters or
decorative light fittings, where moving the Junction Box in to position after wiring
could cause stress on the terminations.

Personally i have always used Hager J501 junction boxes for down-lights.

Did any of the older style Jb's have strain relief? All the ones i have seen on the job generally don't have it.

 

[DPG]

Quite often, people just used to use the 'normal' brown jbs and leave them dangling under floorboard and god-knows where

 

[7029 dave]

Quite often, people just used to use the 'normal' brown jbs and leave them dangling under floorboard and god-knows where

Always screwed mine down to the joist, Dave tight as good as any MF jb.

 

[DPG]

Always screwed mine down to the joist, Dave tight as good as any MF jb.

Agree. Done up nice and tight and the jb screwed to the joist is good for years. Daz

 

[Jay Sparks]

Ok, so you fix the jb to the joist. The cable that comes from it to the down light will still move around when, as you say, you are messing with the light. Not having it fixed would actually be better for the terminations.
bnin

 

[DPG]

Ok, so you fix the jb to the joist. The cable that comes from it to the down light will still move around when, as you say, you are messing with the light. Not having it fixed would actually be better for the terminations.
bnin

No, use a JB with strain relief for both the incoming and outgoing cables. Doesn't have to be fixed then and no dangr of cables working loose. Daz

 

[Andy78]

Ok, so you fix the jb to the joist. The cable that comes from it to the down light will still move around when, as you say, you are messing with the light. Not having it fixed would actually be better for the terminations.
bnin

The reason you would fix the JB to a surface is so that you could add external strain relief in the form of cable clips.

 

[Jay Sparks]

But how can you clip the cable supplying the down light. LiKe i said, there is very little chance of movement on the terminations if the job is done right. How often do you need to take the down light down.

 

[ipf]

Heavens above! We're 'outlawing' decently installed, unfixed brown jb's, above recessed lights when you look at the state of some of the items we come across. Let's get real.....

 

[DPG]

To be fair, I don't think anyone is outlawing decently installed traditional round junction boxes! Daz

 

[Andy78]

All that's being stated is what's currently compliant and what's not.
This may or may not have a bearing on what makes sense or has a bearing on real life issues in installs.

 

[ipf]

To be fair, I don't think anyone is outlawing decently installed traditional round junction boxes! Daz

'outlawing'....being used as a term of phrase, not literally......but almost as good as, and I'm sure some would take it that way.
It's just making mountains out of molehills, again.

 

[Midwest]

Common chaps you can't argue DPG's point. Brown circular JB's have been around donkeys years. They were designed to be fixed to a surface, joist perhaps, and the cables entering them were clipped to said joist. No strain likely on terminals. That was how I was taught as an apprentice. Over the cause of time, these JB's have been used in a way they weren't designed for, done it myself.
I very rarely use them now, preferring MF boxes. Cables entering fittings (sockets etc) are normally clipped, in trunking etc or covered over with plaster. Is someone takes off the faceplate (Mr Decorator), well you can't cover all bases, and is another matter entirely. All of the of the downliight I've fitted have a cable strain clamp. Not the case for all other luminaires I grant you.