We own around 3 acres and we are located between two roads. The one electric line on the front road feeds the main house with a meter. The back road electric line feeds our garage, trailer, tent building, and the well pump that feeds the garage, trailer, and main house with its own meter. Can you hook one whole house generator to run either electric line or both if needed at the same time?
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The issue is neutral.
Presumably you will be using transfer equipment at each location (generator interlock, ATS, or manual transfer switch) to switch the loads between utility and generator. Normally, this equipment does not switch neutral, because that is not required when 1 generator feeds 1 panel on 1 service.
However, since you are feeding 2 panels, you must switch (isolate) neutral on all but one connection. That means using a 3-pole transfer switch for 240V or 2-pole for 120V.
Because if neutral was not switched, the 2 panels' neutrals would be continuously connected via the skinny little neutral on the generator's wiring. What happens at the house when the big service neutral wire breaks, which happens all the time? House neutral will path via the generator wiring back to the OTHER structure's panel and then to its neutral feed from the utility. That skinny little generator line is carrying ALL the service neutral from a whole house. That's not acceptable. Having "all but one" structure switch neutral solves that.
Harper - Reinstate Monica
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The simple answer is yes you can.
The practical answer is not likely.
You would have to set up a redundant feed at the power sources with a tie breaker to have the facility able to be run by either feed. Then set up a genset to run in the event of a total failure. The cost factor would be overwhelming for most of us. Thus making it not practical for a single family residence.
manassehkatz-Moving 2 Codidact
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Retired Master Electrician
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Sure, that's no problem.
When a backup generator is connected to a building, some kind of transfer switch is placed at the three-way connection between the sources (grid power from the meter, and the on-site generator) and the load (the building). The transfer switch selects which power source feeds the building. It also prevents the two power sources from being connected directly to each other.
A transfer switch might be automatic or manual. Sometimes it's as simple as an extra circuit breaker installed in the panel along with a sheet metal gizmo (an "interlock") so that only one of the main breaker or the generator breaker may be turned on at a time.
Now, as far as connecting two buildings to one generator: a transfer switch is installed on each building in the usual way, and cables run from the generator to the transfer switches in the usual way. It doesn't matter that there are two cables leaving the generator.
Sizing of the generator's capacity must be taken into consideration, as must the distance involved for the wiring. It might turn out to be more economical to have two generators with short wiring rather than one generator with long, heavy wiring crossing the property.
Greg Hill
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