Safe install?

xr4x4 · 14 Sep 2011

Hello,

Doing some work in a workers farm cottage and while changing a light switch I took a picture of the CU, as Im not sure if it's safe?

TT earth.

Will upload pic tomorrow as stupid iPad won't allow me to upload pics.

plastic CU is half protected by integral 80ma rcd but there is a metal coin meter fitted after the main meter, which looks like it's not earthed.

Is this right?
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JohnW2 · 14 Sep 2011

xr4x4 said:
TT earth. .... plastic CU is half protected by integral 80ma rcd ....

Commenting just on that bit ... when you say 'half protected' do you mean that half the circuits are protected by the RCD? If so, given that it's TT, the fault protection on the other half of the circuits will obviously not be acceptable. ... and that's before you start worrying about the metal coin meter.

Kind Regards, John.

comms · 14 Sep 2011

The big problem you have here is
"Farm"
lucky there is even an rcd in the board.

Lectrician · 15 Sep 2011

Is using a split load board as discribed, you should have a main 100mA time delay RCD up front.

The meter may be metal, but they do not have earth terminals and are not intended to be earthed. I would assume the electrics within are double insulated.

JohnW2 · 15 Sep 2011

Lectrician said:
Is using a split load board as discribed, you should have a main 100mA time delay RCD up front.

Indeed - as I implied previously, assuming what is being described is a split-load arrangement.

Lectrician said:
The meter may be metal, but they do not have earth terminals and are not intended to be earthed. I would assume the electrics within are double insulated.

Most of the metal coin meters I've seen are of very old designs, in which case I would not put too much money on their being double-insulated. In fact, I think I've got one in the cellar, so will try to have a look! For a start, IIRC, I think the cables enter/leave simply through holes (maybe with grommets) in the casing - would that be acceptable as 'double insulation', I wonder?

Kind Regards, John.

Lectrician · 15 Sep 2011

Most of the meters have a plastic area around the bottom of the meter for the tails, and the cover over the terminals is plastic too. The mechanisms may be a metal cover. The whole lot is usually spray painted the same colour - often a metally colour.

JohnW2 · 15 Sep 2011

Lectrician said:
Most of the meters have a plastic area around the bottom of the meter for the tails, and the cover over the terminals is plastic too. The mechanisms may be a metal cover. The whole lot is usually spray painted the same colour - often a metally colour.

Maybe it's the metallic paint that had me fooled, then. When I get a chance, I'll have a grope about in my cellar and see if I can find a specimen to examine.

Kind Regards, John.

Adam_151 · 15 Sep 2011

When I last came across one of the meters in question I did try and look for double insulated symbol, and did not find one (granted it was quite an old example). With the absence of the symbol one is forced to conclude that it is not a class II item (or at least hasn't been assessed/type tested to see if it is), therefore if unearthed would not comply.

xr4x4 · 16 Sep 2011

pics

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Spark123 · 16 Sep 2011

TT install with non-RCD protected circuits is very dangerous.
I don't follow the logic of having a nice MEM board and shoving a Merlin Gerin breaker in it, (although I also like Schneider stuff as well)

seasickstevie · 16 Sep 2011

That slot meter is a Smiths VT - they used to be rated at 40amp I believe.
The case is all plastic. No metal apart from the innards - which you can't touch. And the coin box - which does not come anywhere near the electrical components.

westie101 · 16 Sep 2011

If the coin meter is a private one, there should be at least a fused switch between it and the credit meter.

Lectrician · 16 Sep 2011

In terms of earthing, that meter does not require it.

The meter should have a DP isolator infront of it to comply with the regs - it needs a point of isolation. A switch fuse would also be acceptable, and SOME DNO's used to specify this, although not so much these days.

You definantly either need a TN-C-S earth connection provided, or install a rod and RCD.

You need a blank in the old MEM CU, and that merlin breaker does look to be cobbled in. Those MEM breakers are readily available (or the equiv MEM that will suit).

xr4x4 · 16 Sep 2011

Spark123 said:
TT install with non-RCD protected circuits is very dangerous.
I don't follow the logic of having a nice MEM board and shoving a Merlin Gerin breaker in it, (although I also like Schneider stuff as well)

Lights and cooker aren't rcd protected.

Lectrician · 16 Sep 2011

Lights, Cooker and something else!

These circuits NEED protecting by an RCD.

The easiest way to sort this would be to place a 100mA time delay RCD infront of the CU - This would not comply to the 17th edition, but as your not working on those circuits as such, just sorting this issue out would be preffered.

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