I have an older diesel generator, with an old panel, from an older ship, that i want to connect to use as a backup power supply.

Generators specifications: enter image description here

The problem that I have is that there is no neutral that is coming from generator, however it has two powerline, with L1, L2, L3 and Ground each.

Here is what it look like inside the panel:

enter image description here

I also conected both of generators output together, but i dont know if that was corect.

Here is also the picture of how the panel looks on the outside:

enter image description here

Can you please help me with how to conect everything, and / or point me to some good guide to follow?


  • You say 3 pairs come out of the generator but then you say boyh. So I am lost. It is likely the generator is 3 phase, so you probably shouldn't connect all the lives together. Commented Sep 19, 2023 at 8:23
  • the is 2 output from generator, both of them have 4 wires inside, L1, L2, L3 and ground
    – demon
    Commented Sep 19, 2023 at 8:27
  • You want to use this for a house? In what country? Do you have a way to maintain or obtain fresh diesel for it when needed?
    – jay613
    Commented Sep 19, 2023 at 18:22
  • Actualy its a barge that im working on, in Sweden, diesel is not an issue
    – demon
    Commented Sep 20, 2023 at 19:11

2 Answers 2


Your generator delivers 3x400V in "delta" configuration, without neutral. We call that "farmers triple phase" here. It's perfectly fine and legal for triple phase motors, while saving one conductor, but unsuitable for everything else.

For the 5 pin connector you need an neutral. An "lost neutral" is serious and the cause of many house fires.

The logical choice would to rewire it to 3x230V in "star" configuration, where the center forms the neutral.

Given the expected work, current state of the generator panel, available power of the generator and risks involved, I'd ask an licensed electrician or trade the current generator for an better suited model.

Some things that I've noted but cannot write in an coherent text:

  • An transformer would also work, but prohibitively expensive for the capacity of the generator.
  • The generator panel seems to be heavily modified. I doubt that it would be safe in the actual configuration.
  • The powerful generator (130 KVA!) has also detriments: If you get a short circuit somewhere, the immense short circuit current could overwhelm regular household circuit breakers. Calculating the needed current breaking capacity is beyond my abilities. I wouldn't expect that an 10KA peak breaker to be sufficient. When one defines the needed breaking capacity he takes in account the distance from the transformer to the house. In your case you have the transformer in your backyard. Perhaps here you are entering the realm of those "molded case circuit breakers".
  • Thanks, it will probably be an transformator, it was one together with generator, but didnt know why it was needed. Legaly i have papers needed for work, but honestly i have no knowelege at all in electrical field.
    – demon
    Commented Sep 20, 2023 at 19:14
  • @demon I don't want to sound rude but If you don't have the knowledge then better ask an pro. Those powers are a league more dangerous than the average house supply. You deal with amperages than an normal welder would use, while exposed to potentially fatal tension. I've seen exploding transformers in way smaller dimensions, and you are dealing here with 130KVA!
    – Martin
    Commented Sep 20, 2023 at 20:32

The way to create a neutral from three phase power is a transformer. For your application you want a Δ-Y (delta wye) transformer and a suitable ground. the generator is connected to the primary(Δ) and the load is connected to the secondary(Y). but you still do not have a neutral until you bond it to ground, and in most cases that is the ground for the generator, load and building; and in many cases when the building ground is not large enough a dedicated ground.

Not only do you want an electrician for this You want an electrician with Industrial experience or a master electrician and in many jurisdiction an engineer.

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