This one has me stumped. I'm not a Pro but not a novice electrician either. Advice and suggestions appreciated.
Included on my home's master panel is a 100 amp breaker that feeds power to an external garage. Voltage on both leads to and through that breaker is about 124 volts. The wire connecting the two buildings is aluminum #2 AWG, or possibly larger. It's big. This home was originally built by an electrical contractor as his own home. He didn't take shortcuts. There are 3 wires including the ground wire. They run through an underground conduit. The distance is probably 50 yards.
I first noticed that my garage door would energize but only barely start to open, then stop. (I could get it to open under power if I manually assisted.) Next I noticed that half my florescent lights were flickering. I tried running a table saw and it would run but not at normal speed and it "sounded sick".
So Ok... I'm getting a power loss somewhere, but where?
I first suspected the 100 amp master panel breaker itself was bad, and indeed, it probably was, so I replaced it. Didn't solve my problem, however.
After replacing the breaker, I again checked the incoming power on the external garage's panel. Voltage on one line was about 120, as expected. Voltage on the other was about 90. That's with all breakers in that panel off and no load whatsoever. Putting a load on (like turning on the florescent lights) dropped the voltages to about 100 and 70 respectively. Putting more load on (turning on the table saw) made those drop to 80 and 30.
I suspected a grounding problem and checked and tightened all ground connections in both panels. All seemed good and tight, but I removed the main ground line coming from the master panel anyway, checked it for condition, and reinstalled it.
Nothing helped.
I began to suspect a wire problem, perhaps a partially broken or corroded line somewhere in the conduit underground. To test that, I reversed the two wires at the master panel's 100 amp breaker, then measured the incoming voltages again on the garage panel. I expected to see the voltage drops reverse to match the wire change, but they didn't. The readings were still as they were before. That would seem to eliminate a bad wire problem.
BTW, this upper garage panel also powers in the summertime an underground deep well pump without any problems. There has always been plenty of power for that -- no notice of any dimming or power drops when the pump cycles or when starting up power tools, such as a compressor.
At this point, I'm out of ideas. Anyone out there have some to share?
Included on my home's master panel is a 100 amp breaker that feeds power to an external garage. Voltage on both leads to and through that breaker is about 124 volts. The wire connecting the two buildings is aluminum #2 AWG, or possibly larger. It's big. This home was originally built by an electrical contractor as his own home. He didn't take shortcuts. There are 3 wires including the ground wire. They run through an underground conduit. The distance is probably 50 yards.
I first noticed that my garage door would energize but only barely start to open, then stop. (I could get it to open under power if I manually assisted.) Next I noticed that half my florescent lights were flickering. I tried running a table saw and it would run but not at normal speed and it "sounded sick".
So Ok... I'm getting a power loss somewhere, but where?
I first suspected the 100 amp master panel breaker itself was bad, and indeed, it probably was, so I replaced it. Didn't solve my problem, however.
After replacing the breaker, I again checked the incoming power on the external garage's panel. Voltage on one line was about 120, as expected. Voltage on the other was about 90. That's with all breakers in that panel off and no load whatsoever. Putting a load on (like turning on the florescent lights) dropped the voltages to about 100 and 70 respectively. Putting more load on (turning on the table saw) made those drop to 80 and 30.
I suspected a grounding problem and checked and tightened all ground connections in both panels. All seemed good and tight, but I removed the main ground line coming from the master panel anyway, checked it for condition, and reinstalled it.
Nothing helped.
I began to suspect a wire problem, perhaps a partially broken or corroded line somewhere in the conduit underground. To test that, I reversed the two wires at the master panel's 100 amp breaker, then measured the incoming voltages again on the garage panel. I expected to see the voltage drops reverse to match the wire change, but they didn't. The readings were still as they were before. That would seem to eliminate a bad wire problem.
BTW, this upper garage panel also powers in the summertime an underground deep well pump without any problems. There has always been plenty of power for that -- no notice of any dimming or power drops when the pump cycles or when starting up power tools, such as a compressor.
At this point, I'm out of ideas. Anyone out there have some to share?