PME earthing advice

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Hi, all,

I’m looking for opinions on earthing arrangements for a project I’m involved with. The site is 60m by 60m and will involve ten houses and flats. The supply is at the site boundary and is a Bemco Board with metering for each property with a 25mm SWA 3 core to each via a switchfuse. The earthing is PME. Although there is bonding for the internal gas, the gas supply pipes like the water are plastic, so probably not an effective bonding path.

This would leave the whole site effectively relying on one earth point at the Bemco board. Whereas it’s not my decision on the job, I’m not comfortable with this. Any thoughts?

Thanks.
 
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Have you looked at BS 7430 Code of Practice for Earthing?http://shop.bsigroup.com/ProductDetail/?pid=000000000030262045
 
Bear in mind that the PME earth ends at the meter position as it cannot be used on private wiring or networks.

Even if the DNO provided a non PME earth it would be exactly the same
 
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Just jobs I've worked on in the past/posts about exporting PME, I have put garages and outbuildings on earth rods before with another company. I'm not sure if the same applies here. I would hate to see a job done wrong that I'm involved with, even though I'm just doing 1st fix.
 
PME earthing is fine for this application. Have you asked your electrical contractor for his opinion?
 
Even though the PME 'ends' at the Bemco board, the installation is still PME.
If the designer does his job properly then the main earth to each property will need to be sized according to table 54.8. The supply neutral will be the one supplying the Bemco, not the one to each property.
If the designer has decided to omit main bonding at each property then that's his call. The 25mm² earth in each swa will be good up to a supply neutral of 95mm².
 

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