I'm planning to use a generator to bridge longer power outages. Both the house and the generator are single-phase. If the main breaker is off, it will only disconnect the phase, the neutral will still be connected to the grid. Now if a generator is added, it would share neutral with the power grid. Is that a problem?

Disclaimer: I'm aware of all the other risks involved. The generator will only have 2KW, all bigger sinks will be unplugged prior, the circuit used for the feed supports 10A @ 230V and already hosts most of the devices that need powering.

  • \$\begingroup\$ How do you connect your generator to your "essential" circuit? If you use some sort of transfer switch, you should get one that switches the neutral as well as the hot. If you don't use a transfer switch, do you bypass the circuit breaker entirely? If you still use the circuit breaker, then how do you isolate the generator from the grid (it has to come back sometime, after all, and your generator will be out-of-sync)? \$\endgroup\$
    – KTM
    Feb 10 '15 at 20:52
  • \$\begingroup\$ @KTM: There's no requirement to switch the neutral. \$\endgroup\$
    – Dave Tweed
    Feb 10 '15 at 21:14
  • \$\begingroup\$ I have a mains breaker installed by the electrical company, which is openly accessible, and I plan to use the RCD on top. They are in two different places, too. And yes, I plan to get a more professional option installed, but they scheduled an outage for tomorrow, so I'm a bit in a hurry. :) \$\endgroup\$
    – Mantriur
    Feb 11 '15 at 0:36

There is NO problem with the neutral conductor remaining connected. Most electrical codes REQUIRE the neutral to remain connected between the main (grid) supply and the backup supply. Also note that the neutral conductor is bonded to earth ground, usually at the meter socket.

Be aware that most electrical codes require the use of a transfer switch between the grid and backup supply. This is a switch that has mechanical interlock to guarantee that under no circumstances will you ever back-feed generator power back into the utility lines.


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