Check out some similar questions!

servon · Oct 30, 2013, 06:35 PM

I have balanced the load when installing a new 200 Amp. In my home home, but when we turn the window A/C (115 V), the lights in the same bedroom flicks. Adding a separate circuit for the A/C will probably solve the problem. However, is it part of the balancing the load job, or is a separate issue. I have a discrepancy with my electrician.
Thanks,
George

hfcarson · Oct 31, 2013, 04:44 AM

It sounds like the momentary blink of the lamps is something most of us experience. When a significant motor load starts up it will cause a very short voltage dip... this is the likely what you are seeing. Most of the time this is normal. A separate circuit is likely to reduce this "blink".
Balancing the loads connected to a panel is a different issue although a severely unbalanced panel may aggravate the "blink" . Has an imbalance been measured? Has the main circuit breaker ever tripped?

stanfortyman · Oct 31, 2013, 11:25 AM

It is nearly impossible to balance a load in a home. The usage is far to transient and erratic. At the same time, you'd have to go out of your way to imbalance it.
What did you do to balance it?

Dimming lights are sometimes just normal and can't be helped. Even running a dedicated line might not solve it.

donf · Oct 31, 2013, 12:32 PM

Balancing the load on a panelboard is basically a crap shoot, particularly on a residential panelboard.

Basically, you try to put the same (or as close as you can come) load in amperage on each of the panelboard's phases.

What you are describing is not a balancing issue. It is more indicative of a circuit carrying an inrush load (High amperage peak) when something starts up, as in your A/C.

When laser printers were first coming into the residential marketplace, there were an enormous number of complaints about lights dimming every 4 seconds or so. What was happening was that the printers (usually connected to a 15 amp circuit) would have to keep the fuser hot so every 4 seconds there would be a 15 amp inrush which would cause the surrounding lights on the circuit to dim.

If the printer had ben on a 20 amp circuit, you would never see this condition. So my suggestion is to either change the circuit to a 20 amp circuit or put the A/C unit on its own dedicated 20 amp circuit.