wiring problems and build regs book

[dave30]

hello my name is david mackay im 30 years old been a floor layer for like 7 years and have decided to become a sparky its the only other trade i have wished i could be all the time not sure why maybe cause its quite technical

any way going to trade skills for you next month to do my domestic installer course and im trying to get a bit of knowledge before i turn up im stuck on page 31 of the IEE electrons guide to the building regulation the chart or table for instaltion reference method

i understand what the conductor cross section area is at least i think i do dose it mean the thickness of the cable sheathing if could you explain it


but what really gets me is the numbers under neeth it top row is 16 20 27 37 47 64 85

i understand that what ever is changing is dew to heat caused buy the wire being insulted by other things like insulation or a wall but dont get what tose numbers meen cna you help

 

[telectrix]

the cross sectional area is the area of the copper conductor itself. not the insulation. as i've not got the guide you quote those numbers from, i can't comment on that part of your post without more info.

edit: at a guess, i think those nunbers are the current carrying capacity of 1.0mm, 1.5mm, 2.5mm, 4.0mm etc. up to 16mm clipped direct.

 

[Guest123]

The numbers you are referring to are the all important CCC of the cable in amps having considered an applicable factor.

Read down the columns for for each cable and each method.

 

[dave30]

hello telectrix thanks for your reply

thanks for clearing up the bit about cross section area it makes more sense now

but its not those they are in the colum above ill do my best to give you an exaple below


isulatio refrence methode conductor cross section area mm
1.0 1.5 2.5 4 6 10 16 (this bit i understand)


c) clipped direct 16 20 27 37 47 64 85

b) enclosed in conduit 13 16.5 23 30 38 52 69 it these nmbers

that i dont understand there is mothing on the chart that tells you what they meen

thanks again very very much

 

[dave30]

what is the ccc please


thanks so much for all your help


dave

 

[Guest123]

CCC = current carrying capacity.

The top row are the cable sizes, read directly downwards under each cable size to see the max ccc for that cable against a particular factor.

 

[telectrix]

think of it logically. clipped direct give the best form of cooling, so that;s the highest current capacity. in trunking, the cooling is somewhat restricted, so the ccc will be less. surrounded by insulation is about the worst case, so the lowest ccc.

 

[Bradzz]

Hi and welcome Dave.
Table 41DA page 332/ Left hand coloum is for cable size, top row is for the method, the second row is for how many phases,
then the coloums under each of the rows are for the current carrying capacity Say you had Reference method A first on the list and you was going to install in conduit single phase, coloum 2, cable size look for 2.5mm the cable would beable to carry say 20A.
Now if you take the same cable and change the Method to coloum 6 that same cable can now carry 27A.
Hope this helps.

 

[dave30]

thanks for all your help with question i now understandand with out you guys helping i would not so thanks very very much

im sure il be back there are 4 books and alot of reading


thanks again