tails from meterbox to consumer unit

[ample current]

Just been out to a house today with a builder who is doing a loft extension on a bungalow. The meter box is on the outside of the garage (the far side from the house) which is attached to the bungalow but is a separate building so no access through any personal door.

The tails come into the garage up the wall via a 100a switch into the loft of the garage and on to the consumer unit in the house (guestimate over 10m away). As far as I can tell it was like this when it was built (1983 ish).

The consumer unit does need upgrading to accept the new circuits and some of the exsisting circuits will have some minor alterations.I will also need to re route the tails to accommodate the loft conversion.

Is this allowed using the "no worse than before" scenario or will I have to think of something completely different.

 

[Gazthesparky]

What are you actually asking

Any work you carry out has to comply with the regs

If you are upgrading the consumer unit and having to move the tails you are altering the circuit so you have to ensure your new work complys with the regs

 

[Rockingit]

By the sounds of it you'll need to fit a KMF and then run an armoured out to wherever the CU ends up.

 

[eastlondon]

Most DNO's want meter tails limited to 3 or 4 m depending on what area you are in. You also need to consider RCD protection if they are not surface.
Best option (as rockingit has suggested) is to replace the meter tails with a section of suitably calculated SWA. Gland into a metal switchfuse at the meter end, and gland into a metal consumer unit, or galv adaptable box alongside a plastic one.
You havent mentioned what earthing system you have there, the above assumes TNS or TNCS.

Regards

 

[shanky887614]

Most DNO's want meter tails limited to 3 or 4 m depending on what area you are in. You also need to consider RCD protection if they are not surface.
Best option (as rockingit has suggested) is to replace the meter tails with a section of suitably calculated SWA. Gland into a metal switchfuse at the meter end, and gland into a metal consumer unit, or galv adaptable box alongside a plastic one.
You havent mentioned what earthing system you have there, the above assumes TNS or TNCS.

Regards

?

Forget an adaptable next to fuseboard.

Gland straight into it

 

[HandySparks]

?

Forget an adaptable next to fuseboard.

Gland straight into it

Don't think I'd want to gland a 16 or 25mm² SWA into the typical thin walls of a modern plastic CU. You'd never keep the walls from flexing out of shape. Much better to fix the gland into a galv box and just continue the cores on into the CU, as eastlondon says.

 

[Rockingit]

You're also making an assumption that Mrs Jones will be happy with the sight of an armoured running up the wall!!!

 

[ample current]

By the sounds of it you'll need to fit a KMF and then run an armoured out to wherever the CU ends up.

I take it a KMF is a fused isolator switch like this one http://www.tlc-direct.co.uk/Images/Products/size_3/CGMSF100.JPG

And why does the rest need to be armoured? it indoors in the loft clipped in air out of harms way.

the supply comes out of the back meter box up the wall inside the garage to the isolator switch then on to the cu in 25mm sheathed singles with 16mm earth.

 

[Rockingit]

Yes, like that ^^^. As for why armoured, well if you can guarantee that it's not going to be susceptible to damage, and is surface run, then yes you could use 16mm 6242Y. However, you may well find that there's very little difference in the price between 16mm T&E and 2core SWA anyway, so why not assure peace of mind?

 

[brman]

maybe I missed it but I didn't see anything in the original post that says there is something actually wrong with the existing tails so I think talk of swa is a bit premature.

If the existing tails are suitably routed and of an acceptable size then the only obvious objection is the lack of a fused isolator. If the DNO isn't objecting then what is the problem?

 

[Rockingit]

maybe I missed it but I didn't see anything in the original post that says there is something actually wrong with the existing tails so I think talk of swa is a bit premature.

If the existing tails are suitably routed and of an acceptable size then the only obvious objection is the lack of a fused isolator. If the DNO isn't objecting then what is the problem?

The OP talks of extending the tails up to around 10m and bringing into the new loft. I think most sparks would be looking at a different cabling solution than 6181Y over that distance, and also be considering mechanical protection regardless of whether it's technically required or not, especially if there is building work in the vicinity. Cost wise there's only a few quid in it either way, so why try so hard to NOT do the job to the higher spec??

 

[Rockingit]

Quoting prices from the same supplier -

20m of 16mm 6181Y + 10m of 10mm 6141X = £48.50 plus VAT (tails + earth)
10m of 16mm 6242Y = £38 plus VAT (16mm T&E) (and probably needing to run a separate 6141X as well)
10m of 16mm 6942X = £31 plus VAT (16mm 2c SWA)

and a gland pack is less than £7!!

See?? It's kind of a no-brainer from where I'm sat.

 

[MDJ]

By the sounds of it you'll need to fit a KMF and then run an armoured out to wherever the CU ends up.

agree, or a 16mm2 T&E, nothing wrong with that if the fuse is 80 amps and the calculations okay

 

[Guest55]

what will decide the cable type on this job is where are the gas & water bonds are routed to IMO.
if the MET is in the meter box or close by then you dont need to run the minimum 10mm cpc to the CU and 16mm t&e should suffice if its surface fixed.

but if the bonds run back to the CU in the house then you may need 3 core 16mm swa so as to comply with the requirements for protective bonding.

i certainly wouldnt bother with seperate tails & earth over a long winding route through the house , it will look a bit of a lash up.

 

[Guest55]

and just to add , if the dno service fuse / kmf isolator fuse is only 60A , then you'll get away with 10mm of any cable type for the submains.
;-)

 

[brman]

The OP talks of extending the tails up to around 10m and bringing into the new loft. I think most sparks would be looking at a different cabling solution than 6181Y over that distance, and also be considering mechanical protection regardless of whether it's technically required or not, especially if there is building work in the vicinity. Cost wise there's only a few quid in it either way, so why try so hard to NOT do the job to the higher spec??

Ok, I read it differently. I thought he said the existing tails were over 10m long and that he would need to reroute them because of a loft extension. If re-route means extend them, put them somewhere dodgy or replace them then I agree that SWA would be a better bet.

 

[ample current]

Im not going to be extending the tails by 10m, they already are 10m, I was want to just making sure that what was in place was acceptable (I just need to re route them around the new room in the loft so maybe extending them by a few meters)
The tails are already in the loft from the isolating switch in the garage. the incoming point and the new cu are not changing position. I just want to move the cables in a more convenient position.

Thanks for all your input guys