NICEIC Certification Scheme cable runs niceic requirments

[SLSpark]

Wiring 4 storey house hopefully using this job for niceic assessment
Looking for some advice on cable runs etc in loft area and down cavities.
Firstly the loft will have 300mm insulation put in ,basically looking for best way to lay cables according to regs as the insulation will be in last,
Secondly , existing external walls are being built out about a 25-50mm with existing walls staying intact (gyproc) so looking to see what kind of protection required for cables
Internal walls are just being finished off plastered etc so fishing down to switch points , everything to be wired from loft , and ring main will be mainly vertically run apart from going back up loft and down to stop cables running through ensuite

Any advice appreciated from my questions and any pointers on niceic

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[not clever]

If I was an assessor I might ask "how have you supported the cables in the cavity"
Another might be "how have you avoided damage to the cables in the cavity"
Or "have you taken into account the cavity insulation for cable calcs"
Then there is "how have you over come the possibility of moisture crossing the cavity on your cables"
:wink5:

 

[Octopus]

When you say cavity do you mean behind the new stud walling?

 

[not clever]

Internal walls are just being finished off plastered etc so fishing down to switch points

Who has cocked up then?
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[Octopus]

I must say I'm a bit confued about this. Who would be fininshing off walls if the sparkie hasn't been in??

 

[SLSpark]

no one has cocked up
the external walls are being built out so the cabling will be on the existing surface and will be clipped with spacing of 50mm to the surface
internal walls wont be adjusted ,
this is only for the top level of the house , lifting floors is not practical or even possible,

 

[SLSpark]

I must say I'm a bit confued about this. Who would be fininshing off walls if the sparkie hasn't been in??

THIS IS THE FIRST FIX OF THE TOP FLOOR OF THE HOUSE , CABLES WILL BE RAN ETC WALLS BROUGHT OUT FINISHED THEN ACCESSORIES FITTED
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[not clever]

I think I see. your cables will be clip on what is currently the external face of the property, at a later date a new outer wall is going to be built up from ground level forming a new cavity, in essence the place will have 2x cavities.

 

[SLSpark]

YES (NOT CLEVER) THAT IS IT , AND ALL WIRING WILL BE FROM LOFT AREA
THE RING MAIN WILL COME UP CABLE VOID TO TOP FLOOR AND RUN VERTICALLY UNTIL WE COME TO THE ENSUITE AND WILL GO BACK UPTO LOFT AND DOWN AGAIN (i think this is best if not let me know)
so in all sockets 90% vertically run from socket to socket and when easier we will go back upto loft.
lights are all from loft and switch drops will be from loft area down existing cavity in internal walls .

im basically looking for some guidance on mechanical protection and runs for the cables in loft

 

[SYKRAPS]

No need to shout fella people are only trying to understand fully before they respond.

In an attic space the thing that you need to take into consideration is insulation and the possibility that the cables may run through it, if you deem that the cables will run in insulation that has a depth of 100mm or greater then you need to either derate the fuse size of the new ring final circuit or alternatively upgrade the the cable size to be used from 2.5mm t+e to 4.0mm t+e and this will then satisfy BS7671 aslong as the circuit size is 100m sq or less. You should also satify BS7671 with regard to securing the cables.

You can run the circuit within mechanical protection but to be honest it will not be as cost effective as upgrading the cable size.

 

[ian.settle1]

Second that stop SHOUTING

 

[SLSpark]

what about having the cable clipped in loft along the beams so that it would be above joist level .

the insulation is due to be 300mm thick.

there is going to be fire rated downlights in the ceiling also what measures would need to be taken with regards to the insulation covering the downlights

 

[not clever]

Option 1:
SWA submain on tray from ground floor & put a small cu on top floor.
Circuits from cu, up into loft then do as you say drop to each point.
Bin the ring main go for a radial & use JB's in the loft that way you can get away with a single drop to sockets & use 20mm conduit down to a box, out back of box through the wall to socket.
ensuite having a shower ?
Will probably work out the cheapest option.

Option 2:
50x50 galv trunk from ground floor up to loft & take circuits up that (still think you'll have issues with cable support if assessor asks about your method) & then run as you have said but use 25mm conduit for the drops to outlets if you are still wanting to use a ring (remember VD three storeys is a long way)

What ever option you do you'll need to think of cavity insulation when doing your cable calcs.
Me I'd go with 1 (its what I tend to do for loft conversions)

Cables in the loft, nail a 6x1 round the trusses above the insulation & clip to that, clear insulation away from where you take the cable drops.

 

[ashrow]

I would not even waste my time posting to help you out
Hope you get it all wrong

 

[not clever]

what about having the cable clipped in loft along the beams so that it would be above joist level .

the insulation is due to be 300mm thick.

there is going to be fire rated downlights in the ceiling also what measures would need to be taken with regards to the insulation covering the downlights

Fireguard Loftbrace for 400mm Joist Centers

How long have you been sparking?