Design Question

[Simonslimline]

Are you creating a TT system at the garage and workshop? You can get insulated swa glands so you could still terminate straight in to the cu.

 

[happysteve]

Where can you get insulated SWA glands from?

 

[davesparks]

What's the issue?

The issue is normally electricians who lack the knowledge to design a safe and compliant installation

 

[Darkwood]

To note on this one, one point of isolation is ideal but it is now a recognised acceptable method to have more than one in a domestic if they are clearly marked and all at the origin, I believe it gives examples of this in the guidance notes (Ill stand corrected on that though as I never bother with them).

 

[hightower]

The issue is normally electricians who lack the knowledge to design a safe and compliant installation

I was under the impression it's perfectly acceptable to use the supply earth where extraneous metal parts don't exist in the out building

 

[telectrix]

I was under the impression it's perfectly acceptable to use the supply earth where extraneous metal parts don't exist in the out building

that's correct, but if the supply is PME with extraneous parts in the outbuilding, then the supply cable's cpc must be no less than 10mm to comply as a bonding conductor. ( or a separate 10mm bonding conductor may be used.).

 

[hightower]

that's correct, but if the supply is PME with extraneous parts in the outbuilding, then the supply cable's cpc must be no less than 10mm to comply as a bonding conductor. ( or a separate 10mm bonding conductor may be used.).

Yeah, it mentions all this in an ECS guide Tel, I think it's a good few years old now but still valid hence why it hasn't been updated. The 10mm bonding you mentioned in TN-C-S systems might also be accomplished by rodding the outbuilding according to the guide, but I always thought of TTing an install as a last resort rather than a go to.

 

[telectrix]

Yeah, it mentions all this in an ECS guide Tel, I think it's a good few years old now but still valid hence why it hasn't been updated. The 10mm bonding you mentioned in TN-C-S systems might also be accomplished by rodding the outbuilding according to the guide, but I always thought of TTing an install as a last resort rather than a go to.

yes, because with a TT installation, you're most likely having to rely on a RCD for fault protection due to the high Zs.

 

[Simonslimline]

Where can you get insulated SWA glands from?

Look up, CMP products.com

 

[rolyberkin]

Are you creating a TT system at the garage and workshop? You can get insulated swa glands so you could still terminate straight in to the cu.

The workshop which is up now and acting as a site office will be TT'd to start with as the site is on a temp supply. I will consider exporting the earth when the main supply goes in, not sure what he intends to do down there. Will see this weekend when I go and have a look.

 

[rolyberkin]

Look up, CMP products.com

These look good and would be so much neater than routing through an adaptable box!

 

[davesparks]

I was under the impression it's perfectly acceptable to use the supply earth where extraneous metal parts don't exist in the out building

Yes, it is also perfectly acceptable where there are extraneous parts of you have a big enough earth