Best practice for splicing T&E for high loads.

[BlueLoo]

My shower cable in the attic is damaged.
As i will be boarding over the area next year, i want to replace the damaged part and increase the size of it to comply with load ratings once its buried in insulation.

From the CU to the attic is 6mm2 and simply clipped. Once in the attic, it is currently buried under insulation so i want to splice it at the attic junction and make it good for the new boarding.

I have read that splicing is ok, but a suitable junction box and blocks are required. Also that the junction box should be accessible.

Ideally, I'd run 10mm2 back to the CU but really, I can't without major surgery.

Whats the norm? Can i splice and how best to do it?.

Thanks in advance.

 

[motorbiking]

https://www.cef.co.uk/catalogue/pro...connector-3-way-6mm-terminal-block-pack-of-30

 

[oldbutnotdead]

Yes you can splice in a length of 10mm and it is a legitimate way to compensate for the insulation sketch as long as the 6mm clipped direct is adequate for the load presented by your shower (usually ok up to 10kw).
Joints in a box. Terminal block is fine if the box is accessible (easy enough to arrange in a loft-run up a wall or a rafter or any convenient bit of timber).
Worth putting a note at the CU explaining why the shower cable is 6mm at the breaker and 10mm at the shower

 

[BlueLoo]

Yes you can splice in a length of 10mm and it is a legitimate way to compensate for the insulation sketch as long as the 6mm clipped direct is adequate for the load presented by your shower (usually ok up to 10kw).
Joints in a box. Terminal block is fine if the box is accessible (easy enough to arrange in a loft-run up a wall or a rafter or any convenient bit of timber).
Worth putting a note at the CU explaining why the shower cable is 6mm at the breaker and 10mm at the shower

Great advice, thanks.

Good point about the note as well.

 

[sparkwright]

60amp junction boxes are good for extending shower cables, IF in an accessible location.

Presumably there would be a place to fit the jb between the end of the floor boards and the eaves.

 

[BlueLoo]

60amp junction boxes are good for extending shower cables, IF in an accessible location.

Presumably there would be a place to fit the jb between the end of the floor boards and the eaves.

The existing cable pokes up from the stud wall underneath and is about 2m away from any wall, but your suggestion reminds me that i can "move" the splice accordingly.

The cable is strung like a guitar string atm. Yet another job i have to clean up after the developer. (I've been doing this for the last 15 yrs!)

 

[sparkwright]

If it is just an ordinary loft space (for junk etc) and no floor covering, I see no (real) reason why you can't fit a small access hatch for the jb, if you prefer.

I think Click make the 60amp jb. They are very easy to fit, good quality, and complete with cable clamps.

Presumably you are going to batten the tops of the joists to allow for the existing cables to go under the new floor?

 

[BlueLoo]

If it is just an ordinary loft space (for junk etc) and no floor covering, I see no (real) reason why you can't fit a small access hatch for the jb, if you prefer.

I think Click make the 60amp jb. They are very easy to fit, good quality, and complete with cable clamps.

Presumably you are going to batten the tops of the joists to allow for the existing cables to go under the new floor?

Yes, as much as i can. I am going to use loft legs so I'll have some headroom for the battens.

It isn't going to be a wall-wall boarding either, just a centre section to help me get in and out and around the attic to service the utilities up there and have a spot or two for xmas decs and not crush the insulation.

A JB might be easier to get here in Ireland so I'll have a look at that option

 

[winston1]

A JB might be easier to get here in Ireland so I'll have a look at that option

There are strict rules about DIY electrics in Ireland. Check if you are allowed to do it.

Why not just lay your existing 6mm cable on top of the insulation?

 

[chivers67]

From what I read Winston, he's boarding over this so it really depends how deep it will be under the boards as there's a potential to put nail or a screw through it - by a future resident?

 

[winston1]

He is putting in loft legs so there will be plenty of depth.

 

[BlueLoo]

There are strict rules about DIY electrics in Ireland. Check if you are allowed to do it.
insulation?

Ireland is erm..... Interesting in this regard.

Lots of rules and regs which nobody takes a blind bit of notice of because it's a republic and not doing as one is told is baked into it's psych.

Also, you can't get trades for blood or money and if you manage to find one, chances are you'll be doing it again properly once they have left and been paid.

It's usually me arguing with them about doing it properly, not the other way round.

Laying 6mm2 on top of the insulation was what the last chancer did when he routed the shower cable for me. I was nieave back then and didn't think anything of checking his work.

6mm2 is pushing it for my 9.5kw shower and laying it on insulation more so. Over time, the cable has sunk into it so it's not good enough really.

 

[wundaboy]

Ideally, if there's any way at all to do it, I'd run 10mm2 back to the CU, even if it means surface trunking in a corner somewhere.

 

[bsr]

On the other hand though... Is there any damage to the cable? Take a shower and see how hot it gets.

My thinking being that the current capacity is rated for constant current. Showers are only intermittent use for say 10 minutes at a time so unlikely the cable will degrade. Bear in mind cable is rated for a minimum of 70 degrees Celsius!

 

[John D v2.0]

I cant find 10mm wagos, only up to 6mm, but you can get screw connectors with cable grips
https://www.tlc-direct.co.uk/Products/AAJB60.html