Ignoramus18851 wrote:

That's a nice story. In my case though, the RPC runs on 220V, so
neutral is not a big deal aside from the control circuit. Loose hot
mains wires at the power panel could possibly (but not very likely)
account for dimming lights.

i


If you have a 100 A or less service, or this problem happens when you
already have a heavy load operating, like an oven, electric clothes
dryer, etc. then there may be nothing you can do, given that service.
You noted the RPC, alone, draws 120 A at startup.

If you have a 200 A or greater service, and the problem happens when
no other heavy load is on, then there is just plain something wrong,
and it could be dangerous. A loose connection somewhere between
the transformer and breaker panel is a strong possibility.

One possible way to isolate high-resistance connections is to check
the voltage at the RPC's breaker when it is started. If the nominal
240 V dips below, say, 200 V, that indicates a lot of loss. Work
backwards toward the service entry. If the service entry drops to
about the same level as the previous measurment, then the service
has a high resistance, certainly too high for this load. If it DOESN'T
dip much, then the problem is between the service entry and the load
breaker. If you can spot some place where the voltage drop changes,
like it is OK at the service entry breaker (if present) but dips
at the main breaker panel, then the problem must be between these two
points. Some of these main connections can be very hard to work on,
such as requiring an allen wrench to tighten, so you really have to
be sure the juice is off before touching it.

Jon