Clipped Cable/studs/insulation

[Hefferl]

When clipping cable direct to studwork where insulation is present, how do you avoid the part of the cable that enters the dry lining box being completely surrounded by insulation whilst keeping to safe zones?

Dry lining boxes have to be positioned at least slightly away from studs so that the lugs are not fouled by the studs. This means the cable runs at an angle from the last point at which it was clipped and into the back box. This also means that as the cable does not strictly run directly horizontally or vertically to the accessory that the cable is slightly outside of the safe zones.

This is even worse where the accessory is to be positioned in the middle of two studs - do you have to just accept this and run the cable through the insulation and derate the cable accordingly?

 

[Evans Electric]

I just drop them straight down , most cables , domestically, don't carry anywhere near their rated current , especially switch drops which only do one fitting .   Cookers & showers , you'll have to do the math , as they say , or keep the lagging away from them .  

With downlights , I insist the builder leaves a space for them , you either have downlights or lagging but not both .

Edit :   I always think that , with shower wiring , its not pulling current long enough to be affected by lagging , but thats just my opinion . 

 

[Steve3948]

Safe zone 100mm ??

 

[Badger]

I just drop them straight down , most cables , domestically, don't carry anywhere near their rated current , especially switch drops which only do one fitting .   Cookers & showers , you'll have to do the math , as they say , or keep the lagging away from them .  

With downlights , I insist the builder leaves a space for them , you either have downlights or lagging but not both .

Edit :   I always think that , with shower wiring , its not pulling current long enough to be affected by lagging , but thats just my opinion . 

shower wiring that i install from new or upgrade now is 10mm no iff buts or maybes!

 

[Blue Duck]

^^^ thats what a plumber told me....

Seen some new build stuff with 6mm  headbang   

no you cant have a 10kw shower coz the cable is too thin......

 

[Hefferl]

My biggest concern relates to socket rings/ radials. Ive seen a lot where the cable is surrounded by insulation yet MCBs used are still 32A/20A (i.e. no derating applied)

 

[steptoe]

I sure can, the results of a DIY shower in 6mm that I went to investigate today actually,

can you tell the size of the MCB?

 

[Sidewinder]

45A?

 

[Blue Duck]

50a?

Couldnt tell what the first 2 & last 1 were then the shape looked familiar....it'll be right just a bit of a clean up and some new mcb's

 

[Manator]

I recently did an install and used konex all through the partitions, I just wish everyone would ask for it!! Its brilliant easier to install and far better than leaving to chance.

I think today most electricians are not allowed to fully install to a good standard mainly due to financial constraints, in years gone by we did all house installs using galv conduit for instance. it does not happen these days.

I remember an install I did about 12 years ago we were asked to install a sub main in MICC, about a year ago I got a call from the client ranting and raving that I had installed the wrong size cable!!

Apparently some domestic installer had gone in and said that the 60amp supply cable was undersized and dangerous to use. he replaced the MICC with a 25mm armoured, and told the client to claim from the original installer.

I just love it.

As for cables installed in insulation there are no fast solve all answers, I recently condemned a 4mm cable because the installer had not de-rated the cable. With today's Green Homes i would advise all to do the calcs and de-rate when required. Not a lot of DI's would really know how to do that, but at least those who read this thread will at least try to learn.

 

[ProDave]

If people built "green" homes properly, then cables would be nowhere near insulation, and we would not be having this discussion.

If you want a truly well insulated home then you want good insulation, AND good air tightness.  That means sealing the insulation in so it's not subject to draughts. You then provide a service void within the insulated and sealed envelope for cables and pipes.

Any building that has cables passing through insulation is a compromised design.

It's a shame that VERY few builders know this, so 99% carry on the way they always have, and build mediocre houses.

 

[Manator]

Well said Dave and so very true!

 

[steptoe]

I recently done a coded house,

after many lengthy discussions with the builders regarding a service void I was told I was talking rubbish,

imagine their dismay when they got downgraded 4 codes,?!  :slap

all that money wasted,  :shakehead