DIYbanter - View Single Post - lights dim when boiler cycles

wrote:

When the boiler in my house cycles, the lights dim all over the house.
Is there anything I can do to limit voltage drops like this? My house
has 200amp service; the boiler is on a 20amp circuit with 10 ga
aluminum wire (this is the correct size wire for 20amp); and the cable
between the socket on the outside of the house and the 200amp panel is
enormous.

What can be done? 200amp service for the house is an incredible
overkill. My guess is that the house usually draws 40amp or so during
busy periods, fewer amps otherwise.

Thanks, Michael

Boiler is:
A: Electric
B: Gas-fired
C: Oil-fired

Is it the "boiler" start-up that dims the lights or
is there a circulating pump (Hydronic) which dims
the lights when it starts?

The AL wiring raises a red flag in and of itself...

Answers:

1. Boiler is oil-fired
2. Boiler start-up dims the lights

Why would AL wire by itself suggest problems? I could pull the wire
and replace with 12ga copper but I am not sure what this would do in
terms of voltage drops. Would this likely help?

Michael

Sorry, I didn't mean to imply that the AL wire to the
boiler was causing dimming but rather that if the
whole house is AL wired there could be connections
"somewhere" upstream exhibiting voltage drop under load.

Anyway, some oil burner motors draw significant starting
currents today. If the incoming service from the pole
is "soft" you'll see dimming (at least on that "phase"
or side of the Line). As you note though, a 200 Amp
service wouldn't normally be so susceptible.

To really troubleshoot it, you may have to put static
loads (a bank of toasters, for example) on the circuit
and trace backward with a meter to find where the drop
occurs.

Jim