refrence method

[jamie-spark]

Hi guys what refrence meathod do you use for pvc flat sheathed cable ran in attic not clipped over joists and over the top of insulation cant really make my mind up and there is no specific one that i can see but lots for under ect ie 100/101

Any help cheers

 

[telectrix]

as additional insulation may be added on top of the cable, i,d put it as ref. 100 or 101 ( Table 4A2, page 265 BRB )

 

[malcolmsanford]

100 as your not in insulation exceeding 100mm only use 101 if your going into insulation exceeding 100mm

 

[spud1]

Id go for 100

 

[telectrix]

100 sounds good to me. was just thinking everone's going for this 300mm itchy crap these days. just cover everything with it.

 

[spud1]

You d think modern tech and all that they d invent non itchy insulation. Pink stuff not too bad?

 

[telectrix]

i hate pink. hads to wear a pink tie for dtr's wedding, yuk

 

[spud1]

Was the tie itchy though ?

 

[telectrix]

not itchy, strangulating. i only wear a tie for weddings and funerals. but i'm not going to wear one for my own. back of the van, down the crem, more global warming, job done.

 

[spud1]

Ha ha !

 

[nickblake]

100 sounds good to me. was just thinking everone's going for this 300mm itchy crap these days. just cover everything with it.

they have just installed 200 mm over the existing insulation in 85% of the houses in my area , my concerns are has any one taken into consideration the derating factor of the cables due to this as the method used to be 100 now its changed to 103 !!!!

 

[malcolmsanford]

they have just installed 200 mm over the existing insulation in 85% of the houses in my area , my concerns are has any one taken into consideration the derating factor of the cables due to this as the method used to be 100 now its changed to 103 !!!!

Not if that is loft insulation it would be 101 it's only 103 in a wall and it's not touching the inner wall surface.

Derating values are important and on design of a new installtion or an alteration or addition to an old is paramount. But a common sense approach is in a domestic home is really needed. Apart from a very few circuits ie a fridge, burglar alarm or fire alarm, very few circuits will ever reach critical usage by being on constantly. Lights power and such most likely will never exceed 50% operational hours over a 24 hour period. Of course design and install the most safe and secure installtion but be sensible and use your design experience to the most

 

[jamie-spark]

was thinking you could say clipped direct as the cable has 3 sides to cool. what u think

 

[Des 56]

was thinking you could say clipped direct as the cable has 3 sides to cool. what u think

I think, you think, like I think

Loft insulation may not be the thermal monster that it is sometimes portrayed

 

[telectrix]

it's there to retain heat. retaining heat on your feet..... good. retaining heat on your cables....... not good