cooker switch wiring

photoboy1962 · 15 Aug 2017

I'm in the middle of replacing an old kitchen in a flat I've recently bought, I've bought a new MK cooker switch to replace the existing very old and very large MK cooker switch. When I took off the old switch cover, I've noticed that there is no earth wire coming from the supply side, the only earth wire comes from the bottom junction where the cooker is wired to, this earh is then attached to the metal back plate of the existing cooker switch, is this correct? I would have thought that a cooker would have to be properly earthed.

flameport · 15 Aug 2017

An earth is required.
The earth may be the conduit connected to the box.
Or it may be missing completely.
Further investigation is required.

deadshort · 15 Aug 2017

That job looks 'robust' the back box is bushed onto the conduit this is the earth connection. You need to check that the conduit is earthed at the consumer unit end. Have you had the wiring checked ?

DS

sparkwright · 15 Aug 2017

As Flameport suggests, the metal conduit may provide the earth, so earth wires are taken from the earth terminal of the boxes.

A better picture of behind the switch may help, and I'm not sure what the box in the first picture is actually for.

Maybe looking behind a few random sockets may give a further indication of the earthing arrangement.

Would be worth doing a Zs test to check if the earthing is effective, though as you're not an electrician more basic tests could help at least.

Do not throw that switch away yet because;
a) I doubt another switch will fit that back box.
b) Flameport may want it for his collection!

photoboy1962 · 15 Aug 2017

Thanks for your replies guys, I think to be safe, I'll get an electrician to check it out. I don't want to take any chances with electricity.

photoboy1962 · 15 Aug 2017

sparkwright said:
As Flameport suggests, the metal conduit may provide the earth, so earth wires are taken from the earth terminal of the boxes.

A better picture of behind the switch may help, and I'm not sure what the box in the first picture is actually for.

Maybe looking behind a few random sockets may give a further indication of the earthing arrangement.

Would be worth doing a Zs test to check if the earthing is effective, though as you're not an electrician more basic tests could help at least.

Do not throw that switch away yet because;
a) I doubt another switch will fit that back box.
b) Flameport may want it for his collection!

The box in the first picture is to the left of the switch, it was covered by a blanking plate. The two supply wires can be seen coming from the top, and the wires from the botom come from the cooker junction box near the floor, all the wires then go into the large cooker switch box seen in picture two. My plan was to fill in and plaster over the large original box hole in picture two.

sparkwright · 16 Aug 2017

photoboy1962 said:
The box in the first picture is to the left of the switch, it was covered by a blanking plate. The two supply wires can be seen coming from the top, and the wires from the botom come from the cooker junction box near the floor, all the wires then go into the large cooker switch box seen in picture two. My plan was to fill in and plaster over the large original box hole in picture two.

It would appear that the box with the wires running straight through is solely there to draw wires through the conduit easily.

Not ideal to fill this with plaster as rewiring in the future will be difficult.

Could this box be turned into the cooker switch, if you pull the wires back?

A modern single gang 45 or 50amp switch would fit this box.

photoboy1962 · 16 Aug 2017

sparkwright said:
It would appear that the box with the wires running straight through is solely there to draw wires through the conduit easily.

Not ideal to fill this with plaster as rewiring in the future will be difficult.

Could this box be turned into the cooker switch, if you pull the wires back?

A modern single gang 45 or 50amp switch would fit this box.

The small box in picture 1, that was my plan to use that for the new MK switch I bought, I was planing on plastering over the large hole/box in picture 2, all that will be left in that is the earth wire attached to the box.

sparkwright · 16 Aug 2017

Ah sorry, couldn't have read your comments properly.

photoboy1962 · 16 Aug 2017

sparkwright said:
Ah sorry, couldn't have read your comments properly.

No problem, appreciate you taking the time to comment.

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