UK Advice needed for garage power job

[Sparkzilla]

Advice needed! Ive been to see a job for garage power, the previous electrician has taken a 4mm on a 32amp B MCB protected by a 30mA RCD. But hasnt done anything with, apart from the fact there is no protection and its T&E all straight forward. My ownly question is do i gland straight into a socket and then have a fuse spur to supply a light OR can i install a 2 way board protected by a main switch or does it need to be a RCD main switch.

 

[goasis]

it was a long time ago and yes while being assessed working for someone else and i had the unlucky visit with the company manager aswell so never really looked into it.
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20a mcb at board db1 measured at db2 rewirable fuse metal clad board

What's the supply earthing arrangement? & the actual ze?

 

[westward10]

I assume you mean Zs not Ze as it is in the garage. If you have a Zs of 175 ohm then the circuit to the garage needs addressing as to why it is so high.

 

[drilltoaster]

What's the supply earthing arrangement? & the actual ze?

pme and ze at db1 if my memory serves about 22 omhs

bottom end i couldn't rely on the swa cable earth so installed a rod and isolated the gland earth connection at garage to stop parallel paths

 

[davesparks]

ze is 175 ohms what do you do?

Contact the DNO and get them to fix the high Ze.
No matter what you do with the garage supply the Ze will still be 175

 

[drilltoaster]

Contact the DNO and get them to fix the high Ze.
No matter what you do with the garage supply the Ze will still be 175

i think we have covered to issue i miss abbreviated Ze as Zs

 

[davesparks]

pme and ze at db1 if my memory serves about 22 omhs

bottom end i couldn't rely on the swa cable earth so installed a rod and isolated the gland earth connection at garage to stop parallel paths

If the armour is not in good condition then the cable is damaged and must not be used. Installing an earth rod will not fix a damaged SWA cable.
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pme and ze at db1 if my memory serves about 22 omhs

If the Ze is 22 ohms you still need to contact the DNO as it is way above what is acceptable.

 

[goasis]

That Ze needs addressing, and unless the swa is miles long, surely there is some reason why your zs is so massively high that you could look, into? Loose terminations or something? I'm not sure the solution to an unexpected Zs is to stick an earth rod in.

This is a slightly different scenario to the Op.

 

[drilltoaster]

If the armour is not in good condition then the cable is damaged and must not be used. Installing an earth rod will not fix a damaged SWA cable.
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If the Ze is 22 ohms you still need to contact the DNO as it is way above what is acceptable.

sorry 0.22 my bad (trying to quote and not preproofing what i reply)
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That Ze needs addressing, and unless the swa is miles long, surely there is some reason why your zs is so massively high that you could look, into? Loose terminations or something? I'm not sure the solution to an unexpected Zs is to stick an earth rod in.

This is a slightly different scenario to the Op.

i wasnt looking to get roasted here i just put something out there and asked them to check

 

[goasis]

Ah, that seems more reasonable, that high zs would still need some investigating I think, using the armour as cpc would not account for that reading, and this situation doesn't mean that every outbuilding install needs an earth rod.


Not meaning to "roast" you buddy, I certainly don't know it all, just having a discussion... ?

 

[westward10]

No one is trying to roast you. If you have a Ze of 0.22 and a Zs of 175 in the garage this points to a breakdown of earth continuity, the armour is almost certainly not effectively earthed.

 

[goasis]

No one is trying to roast you. If you have a Ze of 0.22 and a Zs of 175 in the garage this points to a breakdown of earth continuity, the armour is almost certainly not effectively earthed.

Westward, swa armouring is the most obvious place to start looking, but would/could you see similar figures with an issue on the line side of the loop? Loose/poorly made terminations for example?

 

[westward10]

It is possible but this is likely the affect operation of the garage circuits.

 

[davesparks]

Westward, swa armouring is the most obvious place to start looking, but would/could you see similar figures with an issue on the line side of the loop? Loose/poorly made terminations for example?

Yes a fault in the line could cause this, but then everything it supplies would have stopped working, or at least not work properly.
And installing an earth rod certainly wouldn't disguise the problem