Problem with blinking lights

[jaboyd]

We recently completed a residential project where the service was on the opposite side of the house from the garage. We installed dual 150 Amp mains for the service (300 Amp rated service) and dual 30 circuit 150 Amp branch panels in the garage. From one of the branch panels, we ran a 60 Amp 240 volt circuit to the 5-ton heat pump. Although redundant, we chose a 60 amp breaker for the disconnect located at the heat pump (the heat pump is rated at 43 amps). Now the problem. The new home owner has an issue with the lights blinking when the heat pump kicks in. He also says he hears a momentary buzzing noise and feels a corresponding vibration in the room adjacent to the mains (which happens to be his bedroom---his bed backs up to the outside wall where the mains are mounted). The main was replaced and the manufacturer is testing it for possible defects, however the noise and blinking of lights continues. All lugs are torqued and all wire is properly sized. The AC dealer also installed a capacitor starter in the heat pump.

Are we experiencing a normal condition (my lights blink when the AC kicks in!!) or is this a legitimate problem (if so--how do we fix it??). Would appreciate some help. JAB

 

[bob]

Re: Problem with blinking lights

Blinking is normal. You can try to improve the conditions. When the compressor turns on it draws about 5 or 6 time its normal running current. Check and see where the utility transformer is located. It should be as close to the house as possible. If it is several poles away
try to get the utility to install one at the service point. If you have the proper voltmeter
you can measure the voltage drop at the meter
when the compressor is energized.

 

[dereckbc]

Re: Problem with blinking lights

If it is a blink of a second or less, it's normal. If it blinks and the lights stay dim while the unit runs, you have a voltage drop problem.

As mentioned if the transformer is remotely located I suspect it is normal and nothing much to worry about.

Use a volt meter at the panel and observe the voltage while the unit is off, then while on. This will give you more info to work from. Dereck