External meter cupboard on the garage wall.

[mickroyds]

Hi BAS.
I'm using the photo to illustrate what I have seen, I note that the breaker is in the cupboard, some DNO's I believe are not bothered and others have turned their nose up at it.
//media.diynot.com/70000_69504_19862_12887220_thumb.jpg
The actual post I was searching for I'm unable to find, but it was similar and tidier than this without all the other add on's.
DNO fuse --meter--tails to fused isolator--tails out to CU.
Does this contravene any reg's even if the isolator is fitted on the internal wall directly behind the meter box.?


Cheers Mick.

 

[bongos]

Hi Mick. That double pole isolator is there to isolate the supply. It does not provide overcurrent protection.

If you're running your tails more than 3m (I believe some DNO's stipulate 2m) then you will require a switchfuse.

This isn't the same as an isolator. It is required to protect the cable between the main fuse and the CU not to isolate the supply.

 

[ban-all-sheds]

Although it will also function as an isolator.

A metalclad one, a bit bigger, (eg MEM 80ESSCF) would be better for glanding SWA to.

 

[bongos]

True. I forgot that SWA had been mentioned.

 

[mickroyds]

Thanks for your input, I agree, the illustration I was looking for has the DP switched 80 amp fuse type fitted but that was the nearest I could find to illustrate what I had in mind as a solution.

Cheers Mick.

 

[ColJack]

I also wouldn't run the cable in the cavity..
for a start it means that you can't insulate where the cable runs ( and if you do then you have to re-size the cable ), and it also provides something for debris and condensation/water to collect on.

 

[mickroyds]

Getting out of step with the responses here... sorry.

So is there a concensus of opinion or regulation against using standard 25mm tails with a fused isolator at the meter end, placed in suitable trunking to the CU inside the property, any bridging of the cavity could be done with the trunking.
OR
Is 2 or 3 core SWA the way forward.
OR
Mount the CU in the garage and run all the domestic circuit cables back to it.

Cheers Mick.

 

[ColJack]

3 core 25mm² SWA ( or 35mm² depending on distance / volt drop calcs ) is the way to go..

 

[LoveRocket]

Why would 25mm singles (ie tails) in STEEL conduit not be acceptable. A damn sight easier to work with than 25mm SWA!

 

[ban-all-sheds]

1) I'm not sure it would be easier. Even 25mm² tails and a 16mm² earth over a 3m run with no bends would need 32mm conduit. Over 15m distance I would not recommend 25mm² - I'd go for 35mm².

So we've got 2 x 35mm² and 1 x 16mm², over a 15m run of conduit with at least 2 or 3 bends in it. I can't be bothered to track down the factors for that (GN1 doesn't have them), but I'm pretty confident that even 32mm conduit wouldn't be large enough.

You think that an even larger size would be easy to thread and bend?

Plus 3-core 35mm² SWA needs a 32mm gland - using 38mm or 50mm conduit will need bigger boxes to terminate in.

2) The cable costs alone will make SWA cheaper - by the time you add in the conduit, the couplers and bushes, the stock & die (assuming it's possible to cut a thread by hand on 38 or 50mm conduit), the bends or the hire of a bending machine the tails-in-conduit route would be a lot more expensive.