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If I run 4mm T&E from the CU in to a PVC adaptable box, then connect a 3 core SWA to the T&E. CW Gland the SWA and use something like a Piranha locknut (or the wiska product range). The continue the radial vertially through the stud wall to the first socket, then through grommeted holes in the stud to the second socket box.

From a cable choice persepective
Loading Estimated at 5.5kw (included a 1.5 Safety Factor) along an 11m run, would give 3.2 V drop. I appriciate that while the current load works out below the max cable load, it it quite close, so I may go for a 6mm run instead for peace of mind.

Would none of the above be comliant?
 
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If I run 4mm T&E from the CU in to a PVC adaptable box, then connect a 3 core SWA to the T&E. CW Gland the SWA and use something like a Piranha locknut ...The continue the radial vertially through the stud wall to the first socket ...
Where are you proposing that this adaptable box will be - it would need to be accessible for inspection, testing and maintenance. ... and how are you going to connect the SWA to the socket - another adaptable box (again which would need to be accessible)? If you're using 'plasterboard boxes for the sockets, you wouldn't really be able to gland SWA directly to them.
Loading Estimated at 5.5kw (included a 1.5 Safety Factor) along an 11m run, would give 3.2 V drop. I appriciate that while the current load works out below the max cable load, it it quite close, so I may go for a 6mm run instead for peace of mind.
Will the cable be surrounded by insulation? If not, then, even with your 1.5 'safety factor', 5.5kW (about 24A) would seem to be well within the capacity of 4mm² cable (even 2.5mm² might be adequate), let alone 6mm², wouldn't it? Am I missing something?

Kind Regards, John
 
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Hi John,

Thanks for your reply.

Sorry, I should have mentioned that. The Joint box I'd mount to the cable tray thats sits above the suspended ceiling (running above the stud wall), so its accessable via the suspended ceiling.

The stud wall will be insulated, so does the max current capacity drop to 26A for that condition?
 
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What is a 1.5 safety factor?

Anyway, if your load is 24A x 1.5, then 36A so you will need a 40A MCB and therefore, with the newly mentioned thermal insulation, 10mm² cable.

For two sockets ???



The job seems nothing out of the ordinary but, especially as it is commercial, needs someone who knows what they are doing.
 
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For two sockets ???

To be honest, Ive over egged it on what might be plugged in just be safe, Ive assumed things like a coffee machine, water dispensor, vaccume, TV, and maybe a laptop or two now and then.
So I came out at about 4Kw to 4.5kw, gave a 1.5 multiply for extra room, so 5.5kw
 
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Actually, Ive put in 2kw for a water dispenser, when it should of been 200w!!

My mistake, so its actually more like 2 - 2.5 Kw
 
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What is a 1.5 safety factor? Anyway, if your load is 24A x 1.5, then 36A so you will need a 40A MCB and therefore, with the newly mentioned thermal insulation, 10mm² cable.
I don't think that's what the OP meant. I think he meant that he estimated the load as about 16A, and multiplied that by 1.5 to get his 'very cautious' estimate of 24A. Even buried in insulation, 4mm² ought to be OK for ~16A, but he would then be limited to a 16A MCB.

The job seems nothing out of the ordinary but, especially as it is commercial, needs someone who knows what they are doing.
Agreed.

Kind Regards, John
 
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What is a 1.5 safety factor? Anyway, if your load is 24A x 1.5, then 36A so you will need a 40A MCB and therefore, with the newly mentioned thermal insulation, 10mm² cable.
I don't think that's what the OP meant. I think he meant that he estimated the load as about 16A, and multiplied that by 1.5 to get his 'very cautious' estimate of 24A. Even buried in insulation, 4mm² ought to be OK for ~16A.

Kind Regards, John

Even more so now I have readjusted the calcs after thinking a water dispensor used 2kw!! :eek:
 
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Sorry, I should have mentioned that. The Joint box I'd mount to the cable tray thats sits above the suspended ceiling (running above the stud wall), so its accessable via the suspended ceiling.
Fair enough, but, as I also asked, how are you proposing to connect SWA to the sockets?
The stud wall will be insulated, so does the max current capacity drop to 26A for that condition?
I'm not sure about SWA (tables don't include that installation method) but 4mm ² T+E buried in thermal insulation has a CCC of 17.5A, therefore adequate for your stated load so long as it were protected by a 16A MCB.

Kind Regards, John
 
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JohnW2";p="3383847 said:
Fair enough, but, as I also asked, how are you proposing to connect SWA to the sockets?

Would this need to be in to metal back boxes with earth glands? If so, I would have to see if I can batten between the studs and attached the back boxes to the batten. Otherwise I could gland to a dry wall box?
 
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Fair enough, but, as I also asked, how are you proposing to connect SWA to the sockets?
Would this need to be in to metal back boxes with earth glands? If so, I would have to see if I can batten between the studs and attached the back boxes to the batten. Otherwise I could gland to a dry wall box?
Well, as I said, you really couldn't gland SWA into a flimsy plastic 'plasterboard back box', so you'd either have to do something like you suggest (although I confess I've never tried glanding SWA into any sort of flush backbox) or else have some separate box where you changed from SWA back to T&E - and, given that such a box would presumably not be accessible, the joints within it would have to be crimped or otherwise 'maintenance free'. However, these approaches we're talking about are all horribly messy, and I really do think that it would be far better/advisable to get it done by someone experienced at installing wiring/sockets in this sort of partition, particularly given that it is 'commercial'.

Kind Regards, John
 
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rusty does not seem to have the slightest idea of all the issues associated with commercial work, and does not appear to have a clue what kind of trouble he could be walking into if he continues to do this himself.
 
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rusty does not seem to have the slightest idea of all the issues associated with commercial work, and does not appear to have a clue what kind of trouble he could be walking into if he continues to do this himself.
I don't disagree, and have cautioned him about this at least a couple of times. To be frank, as I have also said to him, I think he would be best advised to get competent assistance even if it were a domestic installation, since the approaches being discussed really are not very nice, even if they could be made to be compliant.

Kind Regards, John
 
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rusty does not seem to have the slightest idea of all the issues associated with commercial work, and does not appear to have a clue what kind of trouble he could be walking into if he continues to do this himself.
I don't disagree, and have cautioned him about this at least a couple of times. To be frank, as I have also said to him, I think he would be best advised to get competent assistance even if it were a domestic installation, since the approaches being discussed really are not very nice, even if they could be made to be compliant.

Kind Regards, John

Hi John,

What would be the best compliant way of doing this??
 

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