Observations:-

• 9 live wires, 4 neutrals?
• Zero grounds

I was thinking they might be shared. One goes to each conduit. The go to junction boxes, possibly split from there.

No earths. I need to get in the ceiling to see where the shower heater wires run.

I wasn't here when the electrics went in, and stupidly thought it looked the part from photos I was sent.

Edited May 19, 201610 yr by Goanna

The problems with shared (borrowed) neutrals are:-

Firstly the possibility of overload, two 20A supplies returning through a single neutral = potentially 40A in that 20A rated wire => overheating and possibly a fire.

Secondly it is possible that your sparks, having isolated the breaker for the circuit he is working on then breaks the associated neutral, if that neutral has been used by another circuit as well it will become live and lethal!!

I'll bet the ground goes to the roof steel, actually not a bad choice, ours measures as a better ground than the rod. Google 'Ufer ground'.

Thanks for the tips Crossy. It sounds like a complete rewire is in order. At least with all the conduits in, the wiring can be pulled through, so not such a big job. Might as well change the board too. You see from the photos, it looked ok to a layman like me. The white cable is temp power.

It should be possible to bring up to spec. without ripping the lot out

If you can get a "snake" into the conduit to pull new wires you're good to go, but getting around some of those bends is going to be fun

Are you actually still under construction with easy access?

EDIT Whilst it's not best practice you could share ground wires if there's not space in the containment for all that you would need.

Three years from the start mate. The conduit pics were May 14. The roof is nearly 3m high. Plenty room for a thai, but I'm 120kg.

Attach one wire to another to pull through the corners maybe. Thanks for your advice Crossy.

Edited May 19, 201610 yr by Goanna