Discuss Reference method 100/102 or A in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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Scotts

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Hi everyone.
What's the correct reference method for cables (2.5mm t&e 32A? ring main) clipped to wooden joists between the ground floor and first floor. Standard build plasterboard ceiling, chipboard first floor. The joists are to be filled with loft type glass mineral wool insulation. Joists are 8" /200mm with 150mm loft insulation, cables clipped centre of joists.

Does reference method 100 or 102 table 4D5 apply? Or is this reference method A as in installation method 3 from table 4A2 page 386.
 
TL;DR
Reference method for cables clipped to joists in thermal insulation
Looking at the descriptions of the ref methods in table 4A2, p390, I'd say 101. Above a plasterboard ceiling, insulation >100mm. Which is inconvenient, because it means your cables are rated lower than the 20A you need for a ring final. Perhaps just pretend it's 100, no one will know ;)

102 appears to refer to insulated stud walls, but then goes on to jabber about cables touching the plasterboard ceiling. More raw untreated nonsense from the (sh)IET
 
It does say that not all methods can be covered by this scheme in the tables which is certainly true of the usual domestic set up. There is no method that neatly and accurately applies as far as I have seen to flat 6242y cable in walls and ceilings as usually there is no insulation, so none of the above. Every time I fill that section in I think; Well it's not really any of the above but put in one of them to fill the form in. Crazy really as you would think there would be a classification (accurate) for the most commonly used method in the universe.
 
With installation methods increasing its near on impossible to pick the right reference method.
The old A to G reference method was easier IMO.
 
Thanks for all the replies everyone. Should have said the insulation isn't fitted yet. So cables clipped centre of 200mm beams = 100mm from plasterboard. The lowest part of the cable run routed for a short distance, about half a meter, at 60mm from the bottom of the beam to keep a nice clearance from the central heating pipes (these are installed a little high of centre).
Attempting to keep it 20A minimum for the ring final... if they go with 100mm insulation it means most cable will be sat at the top of the insulation or just in it clipped to the beam incase parts are pushed up a little higher when fitted.
This just leaves the short spans of cable around the central heating pipes that will be clipped and around 40mm deep in the insulation, maybe a little deeper again if the isulation fitter pushes it a little higher. Certainly <100mm for method 100.
What are your thoughts?
 
Kewtech KT63

Looking at the descriptions of the ref methods in table 4A2, p390, I'd say 101. Above a plasterboard ceiling, insulation >100mm. Which is inconvenient, because it means your cables are rated lower than the 20A you need for a ring final. Perhaps just pretend it's 100, no one will know ;)

102 appears to refer to insulated stud walls, but then goes on to jabber about cables touching the plasterboard ceiling. More raw untreated nonsense from the (sh)IET
Don't know how to edit my previous post but thinking it would now fit in more with 100 or 102 than 101?
 

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