Do I extend the PME outside to a Log Cabin style building??

[MATTMOUSE]

Please forgive me in asking this same question which normally results in an arguement......lol

I friend of mine needs to have a supply installed (a lighting circuit, a heater circuit and a socket circuit) in a SWISS style log cabin located about 2 metres away from their main home which has a PME system.
The BIG question, Can I used the PME to supply the cabin?...........I wish to use either a 6mm or 10mm 3-core swa for the supply cable, RCD protected of course.

Sorry for this post, just wanted a few thoughts on this particular installation.

A huge thanx for any thoughts guys!!

 

[GLENNSPARK]

Export the PME with a 10mm earth......

 

[telectrix]

any services, e.g.water in the cabin? and i'd put the RCD in the cabin, not in the house CU.

 

[alarm man]

or just make the cabin a tt system

 

[Engineer54]

or just make the cabin a tt system

Only if your an idiot!! lol!!

 

[alarm man]

Only if your an idiot!! lol!!

i'am,ive done one like that,granted the whole place was tt..

 

[telectrix]

well, if the whole place was TT, you'd be exceptional if you could make the garage TNC-S. :ack2:

 

[GLENNSPARK]

You`v got a reliable earthing arrangement with PME....why the hell would you go back to an old fashioned system (TT)? Admittedly it has its place: building sites, Moorings etc but for a perminent fixed install....not if theres TN-C-S available.....keeps cropping up on here this one..........

 

[Rockingit]

If it's only 2m or so from the house (granted that the cable run will be a bit longer), then I can't think of any compelling reason either technically or financially why you wouldn't just extend the earth of the PME over - using either the 3 core or a separate CPC if you've something to bond (unlikely if it's a wood cabin). If you terminate the armour properly and banjo it, then you get the 'bonus cpc' as well, so you're unlikely to have a Zs problem.

 

[ackbarthestar]

Well.... from what you lot are saying on here, another thread, You can use a 6mm2 3-core swa tying the armour to earth at both ends, this will give you an approximation of the 10mm2 earth+bonding cable required.
However, a Log cabin without any extraneous conductive parts will not require PME bonding.

 

[Rockingit]

Slightly off topic - but to my mind, the amount of wire spiralling around a bit of 6mm swa must surely be more than a 4mm csa? (eq. to copper, granted). I don't know, I'm asking. If there's some table / formula for it then I don't know it.

 

[fylthespider]

my two pence worth,
6mm 2 core swa, rcd + mcb in cabin and tt it. saves a bit of cash on cable (not much on 2m run i'll grant you, but worth it on longer/heavier runs) and no nuisance trips in house.

 

[brucelee]

yes there is mate and think its a sticky by lenny have allok in the stickys not sure if in general sectio not have a look about remeber reading it and having a look at the tables

 

[brucelee]

here mate

http://www.electriciansforums.net/e...ulations/23288-can-we-use-armour-swa-cpc.html

 

[telectrix]

the value of k is lower than copper when using the adiabatic. think it's about 50. but you need to know the csa of the armour. think that may be in the sticky brucelee refers to.

 

[ackbarthestar]

Slightly off topic - but to my mind, the amount of wire spiralling around a bit of 6mm swa must surely be more than a 4mm csa? (eq. to copper, granted). I don't know, I'm asking. If there's some table / formula for it then I don't know it.

It's not so much the csa of the steel but the comparative conductivity of the steel compared to that of copper, approximately 1:8, therefore the steel will need a csa of around 32mm2 to have the equivalent conductivity of 4mm2 copper.

 

[GLENNSPARK]

my two pence worth,
6mm 2 core swa, rcd + mcb in cabin and tt it. saves a bit of cash on cable (not much on 2m run i'll grant you, but worth it on longer/heavier runs) and no nuisance trips in house.

give up...your rod and clamp will cost more than a couple of meters of 10mm or whatever...

 

[telectrix]

give up...your rod and clamp will cost more than a couple of meters of 10mm or whatever...

not to mention the time off work with a busted hand from sledge hammering the rod in.
"sorry, mate, oops, missed it"

 

[Rockingit]

Somebody ought to plot the cost equation for using 2/3/4 core swa against 2/3/4 plus external cpc versus length, versus the adiabatic to work out what actually is the best solution.

But then, imagine the beer that could be drunk in the time taken to work it out.

 

[tony mc]

Funny hoW exporting PME always gets alot of debate.

Here is another sticky by IQ

A good guide For 'exported PME' and