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We've got a new oven which shows a diagram requiring 3 wires for our wanted configuration. The old oven however is supplied with a 4 wire cable.

The Old oven has each wire marked as follows:

green wire - Earth

red - PH1

white - PH2

blue - N

Is it ok to just cut plus tape the white wire and only connect up the red. Or does it need to be connected somehow?

Connection box wiring schematic

Edit: enter image description here

2 different configurations are shown.

Left side: 380v ac 3ph

Right side: 230v ac 1ph

We're not supplied with 380v so we can only do the right side configuration. Am I missing something here?

The model of the new oven is 310100, it has no information in its manual regarding the electrical configuration other than to follow the panel. No extra parts came with the oven.

I'm unsure of what those little brackets mean on the diagram.

Edit 2:

The new oven supports single phase or a 3 phase connections. As Simon B and Ecnerwal pointed out the brackets show that a single wire needs to be linked through the points 1 to 3 when doing a single phase connection.

The question still is, what should I do with the white PH2 wire.

Edit 3: Got an electrician to do it. The jumpers were actually supplied. The electrician connected both the red and white wires and only used 2 of the brass jumpers.

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  • I'm in NZ. The wiring from the old oven goes into a 32A socket which has 4 pins. The new oven has a panel to wire a plug into(as shown above). We're trying to use the plug from the old oven for the new one. Dec 31, 2021 at 11:49
  • If you get an answer that leaves one wire not used, would prefer a wire nut or local solid wire connector instead of just tape.
    – crip659
    Dec 31, 2021 at 17:04
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    @crip but converting from a multiphase feed to a single-phase feed requires revisiting the size of the neutral wire. In a multiphase feed, neutral only carries differential current. In single-phase it carries the whole shebang. Dec 31, 2021 at 20:02
  • What is the model number of the oven in question? "3 wires for our wanted configuration" - that is not a thing you should be "wanting", you should let the wiring in your walls tell you which configuration to use. Does the oven have instructions for 4-wire connection? I expect it does. Dec 31, 2021 at 20:06
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    Where it would be really helpful to get some local input would be the question of "if you really have two phases available, might you want to jumper only 1&2 or 2&3, and connect both live phases, if you have 2 of 3 phases (but not all 3) available for whatever reason - but that really cries out for local knowledge of what you have there, not random experiments.
    – Ecnerwal
    Jan 1 at 3:13

1 Answer 1

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You need to check if one phase of your supply is enough to power the whole oven. If it is, then leave the spare phase safely disconnected (in a way that won't let it come into contact with anything), and wire it like in that diagram.

If not, check to see if they provide other diagrams. The use of three terminals marked 1, 2 and 3 strongly hints that the oven was also designed to run on a 3-phase supply.

Edit: I assume by "little brackets" you mean the brass jumpers that should have been supplied with the oven. If so, fit them as shown in the diagram.

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    Yes, theoretically, one phase would give 240v, but at what amperage? You also have to wonder why the property was supplied with 3-phase in the first place. I read up on NZ electrics & it appears very similar to UK. Domestic properties only receive single phase 240v… unless they're in outlying regions with potential power issues, in which case they get 415v 3-phase. I'd still be inclined to ask a local sparky about this before making assumptions.
    – Tetsujin
    Dec 31, 2021 at 17:43
  • The new oven supports a 3 phase connection as well as single live wire connection. We are only supplied with a 240v connection. We tried to wire it like shown in the diagram(connected just the red,blue and green wires and taped the white wire) and the oven would not turn on. Dec 31, 2021 at 22:15
  • No none were supplied, we'll get those 3 jumpers and then try with just the phase 1 wire. If it doesn't work does that mean that the oven doesn't support this 4 wire plug. Jan 1 at 2:39
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    I'm in a NZ subsurb some of our our neighbours have 3 phase, one to power his lathe, and large workshop machinery. another to power fixed appliances like heating. (I watched as powerco blocked my driveway while they replaced their feed which was damaged possibly as a result of an earthquake.
    – Jasen
    Jan 1 at 3:55

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