CU tails burried in plaster !

[ac1951]

Friend asked me to comment on the electrics (just bought an house)

Everything looks OK but one thing concerned me. The CU is mounted approx 6ft high in the utility room and the tails run done the wall approx 4ft buried in the plaster then pass through the wall into the back of the meter box. They do run down the corner of the room within 150mm but I just couldn't help but think what would happen if someone was to drill or drive a nail into the corner with nothing other than the Mains 100A fuse to protect them (one hell of a big bang)

Anyway I pointed out the danger to them but I don't know if any ules or regs have been broken..

Advice, Opinions and comments most welcome. Andy

[Tim S]

ac1951 coughed up some electrons that declared:

Certainly not good to the 17th - in fact 30mA RCD protection on meter tails, though possible, would fall foul of other regs (that one faulty circuit should not impact on other healthy circuits).

So mechanical protection like metal trunking/conduit or armoured cable or simply having the tails visible would be the only way to do it to current regs.

However, regs are *not* retrospective and given the tails are in a "safe zone" I can't think if this falls foul of anything in the 16th or earlier.

If I'm wrong, someone will be along shortly.

Cheers

Tim

[Dave Plowman (News)]

At one time at least the old LEB had regulations about how long ordinary tails could be and I'd guess that wouldn't have complied. They would have required SWA or similar.

[Pete Verdon]

Five feet or so was too long? I understood the norm these days to be three metres.

Pete

[Pete Verdon]

The normal maximum, I mean, not the normal length actually installed.

Pete

[jgharston]

For a new installation, most RECs requires tails to be surface mounted. You have to jump through additional hoops to have them buried or enclosed. IEE regs cover the wiring from the meter (or isolation switch) onwards.

-- JGH

[ac1951]

Going to replace the tails as follows;- Drill through wall immediatly below the CU then run the new tails through the wall and down to the Meter box enclosed in trunking. The Service supply (overhead cables) also run down the same wall Comments ?

Andy

[Tim S]

ac1951 coughed up some electrons that declared:

Without seeing it and being able to see the minutae, I could only offer a couple of things to watch out for:

Do you have cavity walls that *may* contain polystyrene insulation? This can eat PVC (meter tails). If at all possible, unless your sure of the cavity (if any) contents, it might be worth trying to let a couple of bits if uPVC or polythene (PET) pipe[1] in to sleeve the holes and pass the cables through those. It's only the polystyrene issue: double insulated tails are otherwise tough enough to pass through masonry (and often do).

[1] Don't use metal tube if passing the conductors through separate pipes - problems with eddy currents and magnetic effects.

Unless the top of the meter box is well shielded from rain, it might be preferable to come down by the side of the box in the trunking and in through the side of the box - prevents any possibility of water ingress dripping onto live parts. If impractical, consider sealing the trunking well.

Please do watch this space: if I've said any beaulochs, someone will be sure to correct it soon :)

HTH

Tim

[ac1951]

Just a 9" solid wall no cavity. The house is a terraced property with an entry running between it and the nieghbours. The meter box is in the entry and hence protected from the rain and weather. That said, the most convientant access into the box is through the side not the top.

thanks Andy

[Tim S]

ac1951 coughed up some electrons that declared:

Then I don't think you have any problems with your idea. A bit of sleeving is always good as it helps protect the cable from dislodged masonry lumps, but I don't think I've ever seen the "boards" bother. The only regs pertinent are good workmanship and that the cable be installed in a method suitable for the cable. Clean hole(s) that the cable isn't snagging or squashed in should be fine. The outer sheath is pretty tough.

Any way that seems reasonable then - though don't overlook the possibility of driving rain or kids with a hose :) The "boards" would usually specify bottom or back exit, but I've seen side and top done where the box was sheltered.

Cheers

Tim