ECN Forum Forums General Topics of the Trade General Discussion Area higher startup amps cause light flicker?

I just had my 18 year old A/C (York 2CE036A06A, 3.0 ton - unit ampacity of 26.4, 83.5 LRA) replaced with a Trane XE1000 (3.5 ton - min circuit ampacity 28.0, compressor motor 21.0 RLA, 127 LRA, O.D. motor 1.60 FLA) and now when it comes on the lights in the house (anywhere) flicker momentarily.

The house is all electric (major appliances - A/C, house heater, water heater, stove, oven, refrig) with the breaker box label saying its max is 200 amps and the breaker values adding up to be 500 amps. The fuze box size is 50 amps and the outdoor shutoff is 40 amps. All the 240 fuzes are at the top of the fuze box with the water heater and central heat on 1st row, dryer and oven on second row and stove and A/C on third row. The wire size was not changed and the A/C is on the otherside of the fuze box so its wire run is about 4 feet.

The installer (American Metro) came out and installed hard/soft/quick start device (Trane Start Kit - #BAYKSKT252A) at no charge. I guess there was already a GE Capacitor (#97F9882 - which is 40/7.5 MFD,
440 VAC, can film composition) on the AC system . It made very little difference. The lights still flicker just not as noticable as before.

Since the light flickering started after the new A/C was installed I would think that it is the main suspect. I think it is the difference in the RLA startup amp (83.5 vs. 127). Am I right?

>I think it is the difference in the LRA startup amp
That's close.

That's the difference.

The problem may be that the transformer or your service drop or service entrance cable is of too high impedance.

How many houses are on your transformer?
Can you determine the size (kVA) of the transformer?

On the surface, it sounds like you may be running a pretty heavy load anyway but I suspect that you have misadded your breakers. You have to add every single pole breaker and both halves of every double pole breaker. When you are done, divide by 2.