Electrical - A/C & D/C - Light Flicker Throughout the House

I've had this problem going on for a while. ANything that has a high current draw causes lights to dim throughout the house, regardless of which breaker the lights are on. So far, I had the electrical company out to check the incoming service. Checked out OK. I measured voltage on each leg in the box. These were somewhat imbalanced (125V vs. 110V). I haven't worked up the courage to tighten lugs to the main breaker. Is this the next thing I should do? What other steps should I take to isolate the problem?
BTW, I have 200 Amp service in the house so I should get plenty of juice. The wiring is original from 1979, so should be adequate. I have added some lights and replaced appliances, but the only major change is the installation of a new heat pump. If anyone has any suggestions about what I might check, I'd appreciate them.

Thanks,

Carl

hello carl,
it could be a loose connection some where in the panel or in the meter. you can check all the connections in a panel except the main lugs even though the main breaker is off the lugs r still hot. start be turning off the main and checking all the connections in the panel except the main lugs. if every thing is tight here then then move on to the main lugs and meter, u will have to cut the meter seal and remove the meter to do this, befor cutting the seal contact your utility company and check to be sure u r allowed to do this in your area, most areas u are allowed to do this but u must let them know u r cutting it so they can replaice it.with the meter removed power is dead from the bottom set of lugs in the meter can threw the panel, check the lugs on bottom of meter base and on main breaker, if they r also tight then i sugest u contact an electrician and have them look into this, as from here every thing is live.

Sparky has some good ideas if your problem is actually in the panel connections.

The voltage readings you stated were they from the lines connected to the main breaker from the meterbase? If so you have a weak service at the line side of your panel. The Utility company claims wiring to be in tolerance usually from 125 volts down to 100 volts. This may be true but this lower voltage causes stress on you dwelling wiring system and can cause the dimming you are experiencing. You might want to have the Utility company place a 24 hour graph on the main lines and read for variations in voltage over that 24 hour period.

Also when your wiring was installed origianlly were the general lighting cicuits wired in 14 ga. wiring? If this is true, when you plug an iron or other load at the other end of the general lighting 15 amp rated circuit and if that dwelling is 2500 square foot or more in size, then the lighting will naturally dim when that heavy load is applied to that light duty circuit.

If you experience the lights to be dimming all over the dwelling when say your new heat pump or a/c kicks on then the voltage loss will be in the main feeders to the pane, the feeders owned by the Utility company, or the panel size itself.

A two hundred amp service is no longer sure to be of plentiful size when you are using a heat pump or other electric heat system.

If you will provide the following we can calculate the minimum panel size for you if you like.

square footage of dwelling habitable area only not including garage

type of heat gas, electric, oil

type of a/c central, heat pump or a/c only

answer yes or no and how many of the following

elect WTR. HEATER
KIT. DISPSL
DISH WASHER
HOOD FAN
HOT TUB
WHIRLPOL TUB
ATTIC FAN
WTR. PUMP
LIFT PUMP
SUMP PUMP
PADDLE FANS
WINDOW A/C
SPARE
SPARE

elect range
elect dryer

anything else direct connected with a romex over 600 watt including equipment in garages

Wg