What are the cable options for a non-RCD circuit that cannot be buried
50mm or surface wired ?
I think there is a new type of cable kind of engineered just for this situation, but I cannot remember the name. Also, is surface run cable in trunking considered "surface wired" i.e. does not need RCD ? Cheers, Simon.
The spec is BS8436, manufacturers give it names like Earthshield, Guardian, AlSecure, Safe-T-Shield
Earthshield etc,
Also singles in metal conduit, MICC, & SWA.
Yup. The logic goes you are unlikely to drill into trunking!
BS8436 is available from Discount Electrical in cut lengths I believe. It is about the same price as 3c SWA.
You must use a Type-B circuit breaker. You can not use a rewireable fuse, BS1362 fuse or Type C or Type D circuit breaker.
You must use overcurrent protection matched to cable size. You can only use 20A with 2.5mm radial and 32A with 2.5mm ring.
What this means is you can not wire a big 20A draw HVAC lump in BS8436
2.5mm and then use a Type-D 32A to get around the problem of nuisance tripping on compressor startup current draw. Most domestic HVAC are relatively small or in duplicate (redundancy) or in series (air-to- water heatpumps re getting outlet temperature high if not underfloor).In 2011 or 2012 BS8436 from Prysmian will have 4mm added (32A radial) and will all be 600/1000V in place of 300/500V currently. XLPE is also set to take over from PVC (aimed at places stuffed with insulation re grouping, temperature & insulation derating calculations).
Where would you use BS8436? In a thin stud partition where you can not get 50mm from either side and want to maximise floor space. I replaced a short run of SWA in such a situation recently because it will get boxed in both sides and the glands would not be accessible anymore for inspection & testing.
In article , sm_jamieson writes
If the rest of the house is T&E and not 50mm deep then ignore the new regs and continue to use T&E. It hasn't suddenly become more dangerous not to.
I believe that the work is part of an extention, the BCO knows about the work and will want to see the wiring comply with the 17th edition.
I will slowly be rewiring the rest of the house anyway. Has 1 ring circuit for the whole house ! Simon.
*Cough* replace MCB with RCBO for inspection then swap back afterwards *Cough*
You should see that doctor for that cough ;-) Simon.
A cunning plan with one minor drawback.
Simon will have already payed for the RCBO.
If you have payed for it then you might as well use it.
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