PIR Question

[nrbspark]

Carried out a PIR today on a property that was 9 years old and I found 2 or 3 things that I am not sure on what code to give them, they are as follows.

1 SWA going to garage is fed straight into the back of the consumer unit in the house and the armoring is not glanded but has been earth sleeved and terminated in the earth bar of the consumer unit (SWA is a 2 core). I think Rec Code 2.

2 Main electric board fuse is 60 amps and the tails are running about 6m to the consumer unit, the tails are 16mm on a tncs system but there is a DP isolator in the meter cab. I think this is ok but not 100% sure.

3 Main earth cable from the electric boards cut out to the consumer unit is 10mm not 16mm, I think this is Rec Code 4 as I think that this was ok at time of installation.

4 There are no fire hoods fitted over LV spot lights but they are not to close to joists and are not smothered by insulation, I don't think that this requires a coding but a note is worth putting on the PIR.

Can anyone verify or rectify my feelings on the above please so I can complete the PIR for my customer.

Many Thanks.

 

[Phil Mumford]

I agree and the codes you suggest are what I would use for the issues described.

 

[ian3012]

if the tails are 16mm on a 60amp supply, can someone please explain to me why 10mm earthing conductor is not sufficient? thanks

 

[Des 56]

543.1.4

 

[ian3012]

thanks des... i accept that.... which means i've cocked up on a consumer unit change... i.e.... fitted a 10mm earthing conductor with 16mm tails on a consumer unit change....

.BUT.. surely i'll be ok on the adiabatic?

60amp 1361 main cut out.... pfc =2.6kA.... k = 115... t = 0.1 Sec

so S = sqroot of 2600 x 0.1 / 115....... = sqroot of 2.35mm... which is less than 2mm

so is that ok , confirm please?

 

[Guest123]

S = Sq root of I SQUARED x T / K

= 2600 x 2600 = 6760000.

6760000 x 0.1 = 676000

676000 Sq root = 822.1

822.1 / 115 = 7.14mm

10mm still passes.

 

[ian3012]

thanks very much lenny... you can tell i haven't got any books in front of me can't ya?.... (i was forgetting 'I ' has to be squared....)

 

[Guest123]

you can tell i haven't got any books in front of me can't ya?

Me neither...I'm just a bit sad!!!

 

[ian3012]

so really then... to refer to the original post of 'a code 4 for a 10mm earting conductor'... i still disagree with it... the inspector should surely check the adiabatic before he gives a 'code 4' for an earthing conductor that he feels is undersized, when it could clearly be up to the job?

off topic.... i just admitted i cocked up a job.... ( although i never actually installed the tails and earthing conductor, they were existing (fitted by the distibutor, brand new, along with an isolation switch a few days earlier...i can't believe i assumed they would be adequate.... i should have checked more thoroughly)

... i often browse this site...it was a great source of information while i was taking 2391....and i can't recall one poster ever making an oversight, mistake, error... or anything.... does anyone here ever make a mistake?

i'm 46 years old and i've learn't more in life from making mistakes ( my own and other peoples!) than from anything else....

so what i'm saying guys, is this site would 10 times as good (because we would all learn more from it) if it was not just about 'what was wrong ' and 'how to do things right' but also about 'what i did wrong, and how i put it right'

just a thought....