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Posted By Topic: Four Wire Oven to three wire supply

Dec 27 2017 13:06

I'm replacing an old free standing oven with a double wall oven.
Existing power supply is three wire red/black/green.
Oven has four wire red/blue/yellow/green.
Am I correct that red goes to red, blue goes to Black and that the yellow and green are joined together and then connected to the Green?


Dec 27 2017 14:10

You will be correct in thinking it’s time for a sparky. From what you described do you have an old 2nd hand oven?
Someone competent will need to look and confirm loading and correct terminals. Worst case you could end up with a fire if an older installation.

Dec 27 2017 14:59

Yeah it's a ten year old wall oven replacing a thirty five year old free standing.
I have a sparky coming in two weeks to check off all the work to date so just hoping to have it wired up for him to check when he comes.

Dec 27 2017 16:05

Bloody Mickey mouse workmanship. The yellow wire has been confusing me no end so just decided to check the terminals to get a photo and it's just an unconnected wire that's been cut flush with the TPS and left exposed.
It's just a three wire oven.

Dec 27 2017 19:41

a sparky isn't certified to check your work, you will need an inspector

Dec 27 2017 21:15

Is an inspector not a sparky anymore?

But yes. The only thing the electrician will be useful for is connecting the stove to the switchboard.

But he'll have to get someone who is authorised to inspect (inspector) mains work to issue the Coc and liven the work.

Hopefully you haven't put gib up before the inspector has a look.

Dec 28 2017 00:26

Or you could leave the old stove there and let the sparky sort out the wiring and connect it up

Dec 28 2017 05:28

narf narf, maybe you should read the posts, it says existing, so already connected at the board

Dec 29 2017 19:25

[quote]Bloody Mickey mouse workmanship. [/quote]

Just like what you're probably doing, Deapat.

Dec 30 2017 19:49

By the sounds of the scope of work, it would not take a competent electrician long to sort, so the cost element compared to the risk dictates that you get the sparkie involved soonest. Anyone can connect a stove, only a proper sparkie can not only do it properly, but ensure everything conforms to regulations ... after all, isn't your family's safety paramount, rather than cost?

Dec 30 2017 22:48

And then there's my neighbour who asked me to look at his new oven that wasn't working and I found the phase and neutral on the same terminal. He must have shit himself when he turned on the isolator and popped the rewireable....


Dec 31 2017 08:11

Just for interest do they make 3 phase ovens with no neutral?

Dec 31 2017 08:19

Can't say i've ever seen one, you would need some kind of control voltage and 400V control isn't really desirable.

As soon as you go to 3 phase ovens you have some kind of electronic control, PLC's for example or 230v/110v control

Dec 31 2017 09:57

Dec 31 2017 08:11
Just for interest do they make 3 phase ovens with no neutral?”
Quite a few 3phase machines incorporate a transformer to supply the control voltage and therefore don’t use a neutral.

Dec 31 2017 15:43

"Quite a few 3phase machines incorporate a transformer to supply the control voltage and therefore don’t use a neutral."

Yes, i was going to say something about that.

Would have nice if the original installer could have sleeved the blue to black. This is assuming the installed hasn't done a real dodgy job.

I guess that's one of the problem with giving help over the internet

Dec 31 2017 17:21

leaving out the N is only viable when the 3-phase load is always balanced (for normal conditions), otherwise the applied voltages go all to hell as various loads get switched on & off. Certainly not viable for a normal range / oven, where all loads are single-phase 230 V.

Back to OP; what I suspect is happening here is an old four-core flex to the oven, with blue being neutral and red being active. Since the flex is equipment wiring and not installation wiring, the colour rules of "3000" do not apply and there is no need to sleeve the N as black.