Shower Design Document not compliant

[sparkticus]

And I suppose that is the crux of my question - is a cable "passing through" the min specified 50mm insulation if the insulation is "covering" the cable, or can it be classed clipped if I ensure the insulation is not touching the cable.

You would need to convince BC that there is adequate thermal dissipation.
It might be classed as clipped direct but you will have a job convincing BC.

Honestly I see your point in debating with BC but from a practical point of view 10mm CSA is the way to go for future proofing if nothing else.

 

[PrenticeBoyofDerry]

As sparkticus has just said, have a word with your BC officer. Ask them what the problem is and why they think it does not comply?
They don't bite, well most of them don't
Does this cable enter another wall or void where insulation is?

 

[sparkticus]

so we are talking about the stud timber then, not The Community Legal Service.

Caution Live Scaffolding

 

[doni]

2. As the cable is in an insulated stud wall for some of its run, but clipped for all of it, how would this normally be classified - "In wall, in thermal insulation" or "clipped direct", and if it's a grey area, what method might I adpot to keep the CCC higher, e.g. keeping the thermal insulation away from the cable by nails, ... using more CLS to prevent contact ... as when I get the BC visit, I want to be sure of my position.

This is most likely the problem. Did BC see the cable clipped to the CLS in an insulated wall? If so then I assume they will decide it is REF METHOD 2 which limits your CCC to 35 amps. But again you need to get them to specifically tell you what they perceive as the problem.

EDIT: meant ref method 102

1. BC haven't visited - they want to see at first fix - they are commenting from my design document only.

2. The shower cable does not run in an insulated wall it runs in an uninsulated wall and is clipped without insulation (insulation is NOT required by BC, as I have created a VOID with CLS against a back wall where the shpower unit will sit).

3. The "directly insulated" / "clipped direct" question relates solely to my 2.5 radials - which will be in an insulated wall, but I could keep the insualtion away from the cable - and I thought that method 102 would assume the cable is against the palsterboard and covered on one side by insualtion, but being clipped against the upright timbers, it can be away from the plasterboard and away from the insulation (by nailing the insualtion away from the cable) but as PrenticeBoy said, method 102 would stil be OK for radials, but I also have to account for amient temperatures in the roof space, so may go below 20A.

 

[EFLImpudence]

2. As the cable is in an insulated stud wall for some of its run, but clipped for all of it, how would this normally be classified - "In wall, in thermal insulation" or "clipped direct", and if it's a grey area, what method might I adpot to keep the CCC higher,

Clipping the cable to the stud but in the corner so that it touches the outside wall gives you method 102 which has quite a lot less derating than clipping to the centre of the stud - method 103.
21A or 13A respectively.

All in 4D5 and 4A2 (pg 265)

 

[doni]

As sparkticus has just said, have a word with your BC officer. Ask them what the problem is and why they think it does not comply?
They don't bite, well most of them don't
Does this cable enter another wall or void where insulation is?

Yes - I will be calling them, only reason for posting now is I just read the letter from them today and though I was missing something - I don't plan to have the 6mm pass through any insulation anywhere ... I am more concerned with how the 2.5mm radials get treated as they will be in the loft space as well as in the insulation, so while I would be OK with even going with method 102, when I correct for ambient temperature, I'll be below 20A. With themral insulation requirements from BC, it seems that everyone would be running 4mm or clipping to the surface ....

 

[sparkticus]

1. BC haven't visited - they want to see at first fix - they are commenting from my design document only.

2. The shower cable does not run in an insulated wall it runs in an uninsulated wall and is clipped without insulation (insulation is NOT required by BC, as I have created a VOID with CLS against a back wall where the shpower unit will sit).

OK, I see. In that case they may well be misinterpreting because it seems to me that your design would comply with reference method C and you would have 37 amps CCC at 30 deg C. As you say voltage drop will not be an issue. This is where you need to push them to provide an exact reason for their interpretation of the non compliance.

 

[doni]

As sparkticus has just said, have a word with your BC officer. Ask them what the problem is and why they think it does not comply?
They don't bite, well most of them don't
Does this cable enter another wall or void where insulation is?

Yes - I will be calling them, only reason for posting now is I just read the letter from them today and though I was missing something - I don't plan to have the 6mm pass through any insulation anywhere ... I am more concerned with how the 2.5mm radials get treated as they will be in the loft space as well as in the insulation, so while I would be OK with even going with method 102, when I correct for ambient temperature, I'll be below 20A. With themral insulation requirements from BC, it seems that everyone would be running 4mm or clipping to the surface ....

Actually, I think I'll be OK with method 102 for the 2.5 as once in the attic space, it can be classed as clipped direct as it will not be touching the insulation, only the largest correction factor will apply.

I will be arguing with BC about the 6mm though - but I take the point with the future proof of upgrading the shower unit.

 

[sparkticus]

I am more concerned with how the 2.5mm radials get treated as they will be in the loft space as well as in the insulation, so while I would be OK with even going with method 102, when I correct for ambient temperature, I'll be below 20A. With themral insulation requirements from BC, it seems that everyone would be running 4mm or clipping to the surface ....

Yea, you really need to get the radials out of the insulation. Often worth taking a longer rout avoiding the insulation. They (BC) will be right on the heels of that one.

 

[doni]

1. BC haven't visited - they want to see at first fix - they are commenting from my design document only.

2. The shower cable does not run in an insulated wall it runs in an uninsulated wall and is clipped without insulation (insulation is NOT required by BC, as I have created a VOID with CLS against a back wall where the shpower unit will sit).

OK, I see. In that case they may well be misinterpreting because it seems to me that your design would comply with reference method C and you would have 37 amps CCC at 30 deg C. As you say voltage drop will not be an issue. This is where you need to push them to provide an exact reason for their interpretation of the non compliance.

Yes thanks - will do - I get 47A for the 6mm from 4D5?

 

[sparkticus]

Yes thanks - will do - I get 47A for the 6mm from 4D5?

Yep, need better glasses. 47 amps CCC it is.

 

[PrenticeBoyofDerry]

Using ref meth 102 or running in conduit would comply and have the cable above the insulation in loft, but if running in conduit it would be cheaper and quicker then to use 4.00mm cable.

 

[ban-all-sheds]

I have created a non-insulated stud wall (the thickness of Canadian Lumber Size) away from a concrete wall, and plan to clip the cable to the Canadian Lumber Size.
.
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I plan to also clip this cable to the Canadian Lumber Size.
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using more Canadian Lumber Size to prevent contact

if I clip the 2.5 to the Canadian Lumber Size

I have placed some Canadian Lumber Size timber on the back wall, and created a flush wall against this timber using some board to create a void the width of the Canadian Lumber Size. This void will be uninsulated (it doesn't need to be insulated, unliked the partition wall for the radials). The void is 50mm, and the 6mm T&E will be clipped to the Canadian Lumber Size.

Did BC see the cable clipped to the Canadian Lumber Size in an insulated wall?

 

[DetlefSchmitz]

I always thought it stood for Canadian Lumber Standards.

The internet is a funny place though, you will find just about every possible interpretation of the final 'S' if you look hard enough.

 

[ban-all-sheds]

If Canadian Lumber Size is good enough for the Timber Research and Development Association, it's good enough for me