junction boxes under floorboards ?

[Reynardine]

Have read conflicting guidance over junction boxes under floorboards

Hawk : The junction box is inaccessible under a floorboard, breaks regulations and should not be used. Always use an FCU instead or spur off an existing power socket.

Dove : Junction boxes under floorboards are fine. Just make sure they are attached to the joist not just hanging in mid air. Also try not to take two spurs from one box.

How can these two views be reconciled? Have regulations changed w.r.t. junction boxes? Are their different regulations for new build versus old build ?

 

[davy_owen_88]

BS7671 applies to old and new builds. Any new work must comply with the latest edition. There it says something along the lines of all joints must be accessible unless made by soldering, compression tool, and some others that I can't remember right now.

In my opinion, junction boxes should never be put under floorboards or anywhere else where you would sigh, and then complain about how many things you have to move/destroy before you can get to it. Crimps are a far better solution when inaccessible joints are required.

 

[stellafella71]

I'm no expert in this but I can pass on the information given to me by my local BCO (Wirral BC) who signed off the first fix electrics in my kitchen.

When asked I told him that I intended to connect back into the socket ring circuit with junction boxes. He said that this was not allowed and that I had to use crimped connectors which were then put into plastic choc boxes because the connections would be permanent and concealed. A jb doesn't constitute a permanent joint, aparently. I mentioned that I could get to the jbs from the floor above but this was no good.

Not quite sure why jbs are not good anymore but that's what I was told.

 

[davy_owen_88]

Not quite sure why jbs are not good anymore but that's what I was told.

Because screw joints loosen over time and loose connections can lead to overheating and fires.

Connections made under floors are often forgotten about, and when something goes wrong and you need to fault find, the last thing you want to do is rip apart your house looking for a quick fix you made years previously.


I also missed 2 very important points from the first post:

Hawk : The junction box is inaccessible under a floorboard, breaks regulations and should not be used. Always use an FCU instead or spur off an existing power socket.

An FCU is not a solution to concealed joints. Are you confusing two totally separate issues? See * below.

Dove : Junction boxes under floorboards are fine. Just make sure they are attached to the joist not just hanging in mid air. Also try not to take two spurs from one box.

You don't 'try' not to take 2 spurs from one box, you do NOT take 2 spurs from one box. Only one unfused spur can be taken from any single point on a ring circuit. Just because the spur enters a junction box does not mean you can then take 2 or more spurs from there again.*


*Unless you fuse down first using an FCU.

 

[equitum]

Only one unfused spur can be taken from any single point on a ring circuit. Just because the spur enters a junction box does not mean you can then take 2 or more spurs from there again.*

Davy, forgive me if I misinterpret, but did you mean to say you cant take a spur from another spur ? This is subtly different to taking multiple spurs from the same point, which, I'm pretty sure, is quite within the regs.

 

[reggie perrin]

Because screw joints loosen over time

If they are undisturbed then what is the process that causes screws to 'loosen'

 

[RF Lighting]

Vibration from vaccuming

Expantion and contraction of the different metals in the JB due to changes in ambient temperature

Settling of the copper in the terminals

 

[reggie perrin]

Nothing electrical then - so it's carry on regardless.

Cheers.

 

[RF Lighting]

Nothing electrical then - so it's carry on regardless.

Que?


It doesn't matter how the screws loosen. A loose joint will overheat regardless of how it has become loose

 

[reggie perrin]

I was joking...

But then again...

Do sockets, switches etc become loose over time...?

 

[Podooser]

I was joking...

But then again...

Do sockets, switches etc become loose over time...?

Yes but they are accessible.

 

[reggie perrin]

How many sockets and switches have you come across that have come 'loose' over time?

Edit: Spelling.

 

[RF Lighting]

lots, granted not loose enough to fail coupled with the low power flowing through most accesories.

I have work in a nightclub, and removed a switch to find every screw missing. (Vibration from the sound system)

 

[reggie perrin]

How do you know that they weren't 'loose' in the first place?

 

[reggie perrin]

Not picking a fight old chum...