outlet wiring help?

[stephen25uk]

hi guys

i am in the middle of some home renovations and one of these means i need to move my immersion heater.

got it all moved ok,problem is its moved from one cupboard to another so i need to move the wall outlet that supplies it,upon inspection of the outlet its in a metal box with metal conduit ,the outlet is wired red to live black to neutral and the earth is wired to an earth terminal in the metal box,so i am assuming the actual metal conduit throught the hose is earthed?

i was wanting to move the outlet using a 30amp junction box and 2.5mm twin and earth cable,but when i come to conect the cable in the junction box the new cable(new brown and blue) has an earth in it but as i am no longer going to use the metal conduit i have no earth from the original wire to conect it to,so my plan was to use the earth connection of a nearby wall plug and run some earthwire from there to my new junction box.

does my method sound ok,any replies would be good

 

[securespark]

No, you need to connect to the backbox of the original immersion switch.

If the conduit really is the only earth path for that circuit, you need professional eqipment to check the integrity of the conduit connections & that the EFLI is low enough.

Get a pro in, unless you can get hold of this equipment and are competent to use it.

 

[bonebill]

"I am not qualified, so the following is only an idea which may be a complete death trap. Unless you know you are suitably qualified, consult someone who is, e.g. an electrician."

It sounds like this bit is done using conduit wiring using singles. I presume there is an earth connection at the origin point of the existing metal conduit?

That being the case, could we not do something like this?:

1. Leave the existing metal box where it is; eventually to take a blanking plate.

2. Put in a new metal box at the new location.

3. Connect the old and new metal boxes using 20mm conduit. Unless the entire run happens to be in safe zones, use metal conduit e.g. flexible metal conduit £21.99 from Screwfix (30690) [Addendum: It turns out that flexible metal conduit will not comply with the regs for wiring outside of safe zones. Even if you use flexible metal conduit, you will still need to be inside safe zones if it is less than 50mm deep. If you want to go less than 50mm deep outside of safe zones then you would need to use another technique.]. Thread a piece of strong string through the conduit before installing.

4. Using one of the existing live or neutral wires, and the string, pull new (longer) live, neutral and earth wires all the way from the origin point, through the old metal box, and to the new metal box. AFAIK, these wires must be proper 6491X singles and not just some old Twin-and-Earth with the outer stripped off --- they are different!

5. Earth the metal boxes the keep the metal conduit earthed.

If we then look in the old metal box, we should see three 6491X singles coming in from one side, and out the other.

Because we have now run our own earth wire all the way through, we can now get confidence that the appliance at the end will be suitably earthed.

A 100m roll of 2.5mm² 6491X runs at about £19 from Screwfix so a sore £57 for all three colours, but I suspect with a little effort it would be possible to find someone who would sell you cut lengths.

If you get new wire it will probably be brown and blue. Assuming your existing wiring uses red and black, you should take the necessary extra steps to regularise your installation, e.g. fitting a compliant warning notice at the consumer unit.

 

[stephen25uk]

ok guys took your advice,got my wifes cousin around first thing this morning who is an electrician and we pulled some new twin and earth through the old conduit from the cu to the tank took an age to do but am happy now i know its all safe

 

[jason1958]

Cut 1m+ lengths of conduit cable can be sourced...
- www.gil-lec.co.uk
- www.tradingdepot.co.uk

Do a google for "6491X +cut +uk" or similar, will bring it up.

 

[RF Lighting]

Be he just said he's already rewired the circuit

 

[jason1958]

I suspect my reply screen was open before he replied.
Still, may be of use to someone in the future doing a search.

 

[bonebill]

... we pulled some new twin and earth through the old conduit from the cu to the tank took an age to do ...

Ouch. That must have been hard work!