The machine has five wires, three of which are live. I want to wire into a single phase supply using a three prong plug.

It powers a boiler and water pump (for an espresso machine: 220-240V, 50/60Hz, 0.190Mpa/0.65Mpa, 3000W).

The advice I received was to twist the three live wires together and wire them all to the one live prong.

The problem I have is that the the three together is to thick. Is there a way to do this?

Solution: what I found was a connector (not sure what it's called) big enough to take the three wires together with a single wire coming out the other side. Someone else suggested 'wrapping' two of the wires around the third.

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    Unless the machine has a wiring diagram so that you can change it from three phase to single phase this is not going to happen.
    – WarLoki
    Commented Aug 12, 2015 at 9:45
  • 1
    Fascinated by the idea that an espresso machine is set up to run on 3 phase power... maybe you can provide pics/ model number if not an actual wiring diagram. Commented Aug 12, 2015 at 13:21
  • @AloysiusDefenestrate it's presumably of European origin, given the specs, and 3-phase is more widely distributed there, AIUII. I do wonder if the Wattage is really 3100, not 310, which seems rather low.
    – Ecnerwal
    Commented Aug 12, 2015 at 13:35
  • @Ecnerwal -- I learn something new here every day. And agreed that a 310W boiler would be pretty sad. Commented Aug 12, 2015 at 13:46
  • @Ecnerwal: Is three phase more common in Europe than the U.S.? I don't think I have seen anything but large European industrial installations with 3 phrase. In the U.S., 3 phase is in most residential neighborhoods and in the largest houses and medium-plus sized businesses.
    – wallyk
    Commented Aug 12, 2015 at 19:50

3 Answers 3


You can't just fix this with wiring.

You either need to get 3 phase supplied to your location and wired to the device, or you need a phase converter, such as what these guys sell:


A possible alternative might be to use a VFD, such as this one:


In either case, I would seek advice from the device manufacture's tech lines to confirm it's suitable for your application. These devices are generally expected to be connected to a motor, and you have a heater - that is an electrically significant difference.

Also note that I doubt the 3 phase is just powering the boiler. I don't know coffee, really, but I thought high-end espresso machines were pump driven - the pump will be 3 phase too I suspect.

  • 1
    There may also be electronics that run off only one of the legs at 120V.
    – William S.
    Commented Aug 12, 2015 at 17:41
  • Thank you for this information. Pump also, yes. A phase converter would be very expensive for me so I was pleased to find out that combining the three wires is common practice here - I've now down that and it's working.
    – Stephen
    Commented Aug 21, 2015 at 18:11
  • Ok, well I'd say you got "lucky" - again I don't know espresso machines, and perhaps they are generally designed in a way that means they'll work when you rewire them in that way, however as a general rule 3 phase equipment will not work using this approach.
    – RobotAndy
    Commented Aug 24, 2015 at 12:24

Lacking a model number to look up, I would try opening the device near the power cord and see if there is a jumper assembly or instructions for converting to other voltages and phase supplies.

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    This is a poor course of action that would likely result in injury or destruction of the equipment. Do not attempt.
    – William S.
    Commented Aug 12, 2015 at 20:55
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    I upvote WallyK. Its a good idea. Lots of machines have voltage conversion methods.
    – Trout
    Commented Aug 12, 2015 at 21:32
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    +1 to wallyk -- this is the land of DIY, and a prudent individual would unplug the machine and use appropriate caution, possibly including the use of insulated screwdrivers. I've owned (and entirely stripped/rebuilt) a one group commercial espresso maker, and I can assure you that stored high voltage electronics is not one of that machine's attributes. Power goes mainly to the boiler, a little to the pump, and a bit to the brain if it does electronic dosing. Commented Aug 12, 2015 at 23:56
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    @cathode -- many machines are designed for this -- there will be a marked jumper or switch for the job. Commented Aug 13, 2015 at 3:25
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    @cathode: Since the three phase appears to be for heating elements and not a motor, this is a moot issue.
    – wallyk
    Commented Aug 13, 2015 at 17:03

Having recently purchased and rewired from three phase to single phase on a Wega Pegaso coffee machine.
enter image description here
This is what I found and did successfully. Firstly most commercial coffee machines are mono-phase, and can be wired 3 or single phase. The 3 phase has 3 individual lives all acting independently, by joining these together they act as one. One supplies the power the other 2 cancel each other out. You should not risk wiring to a 13amp plug but install a dedicated 20amp supply from your mainboard to a new socket near your machine. I have a 2 group machine, with a 3.7kw boiler, stating 400 volts (three phase). I have had no problems making 4 coffees at a time and all pressure etc are perfect. Hope this helps as it took me nearly a day of searching before I finally was confident to tackle the wiring.

  • Hello, and welcome to Home Improvement. Thanks for the answer; keep 'em coming. And, you should probably take our tour so you'll know how best to contribute here. Commented Aug 3, 2019 at 12:47

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