6mm integrated CPC of 16mm 6242Y used for main earth

[Rockingit]

My adiabatic maths says that for a 16mm main conductor, assumed Ze of 0.2, 80A 88:3 CPD, k as 115.... the earth only needs to be 3.16mm therefore the 6mm in a 6242YH 16mm is more than sufficient.

Anyone disagree?

 

[MDJ]

I haven't worked it out but I suspect your right, and I love the signature haha, thats about 4 or 5 with it now lmao.

 

[Rockingit]

I love the signature haha, thats about 4 or 5 with it now lmao.

Well, I've no idea what the original 'issue' was on about, but I couldn't help but think of something to add.......

 

[Engineer54]

Personally i wouldn't dream of installing a T&E cable as the mains supply tails. So this situation would never arise!! lol!!!

 

[MDJ]

I don't think he means as the tails fella, as a sub main from a KMF switch or breaker I suspect, and if protected by an 80 amp fuse it is going to be Fine IMO, unless it is tails LOL, then your right haha

 

[Brightspark2]

Well ive clearly missed something...

 

[MDJ]

I hope this doesn't come back to bite me LOL, but it looks like a decent question to me.

 

[Rockingit]

Yes, sub mains from a KMF in a dwelling where no bonding is needed.

 

[MDJ]

Nothing wrong with it at all IMO.

 

[Guest55]

amazing how small the cpc actually needs to be when you sit down and work it out isnt it ?

 

[kingeri]

Done it plenty of times, earth calcs check out to me!

 

[kingeri]

amazing how small the cpc actually needs to be when you sit down and work it out isnt it ?

I know a guy who uses 16mm for everything....without fail. He says it's easier. Mind you, probably for the best, he is a plumber!

 

[MDJ]

I always run a 10mm2 earth with a 16mm2 T&E, I am aware it is not always required, as the OP stated as he worked out the calc and he's more than likely right of course, however so what, whats wrong with adding a 10mm2 earth wire with the run? Um nothing, good practice even if unnecessary IMO, another post we can all slate here for fun :tongue3:

 

[Rampantchilli]

Your right MDJ, on installs, but on some occasions where your doing an alteration, it can be simpler doing the calcs, than spending the day running in an oversized or unnecessary separate earth, best practice would suggest 10mm to me tho

 

[infinity]

you wouldn't run a 10mm earth to the cooker switch so why to a sub main? Pointless IMO, of course this is as said no bonding etc required

Although every situation deserves its own design

 

[MDJ]

Agreed no need, doesn't mean its wrong to do it though, but yup no need in most cases.