Electrical Service Question

[Clay Crocker]

I thought I would see if anyone had any thoughts on a home/home shop electrical issue that I have. My girlfriend and I bought a new house last November. In February, after finishing my garage shop wiring I noticed that whenever I fire up my new 2 HP Super Dust Gorilla and/or my General 650 TS (stealth gloats ) that there is a noticeable dip in the intensity of the lights throughout the entire house for the 2 - 3 seconds it takes for the motors to spin up to speed. I never noticed anything like this in my previous house. I did not think too much about it until this summer when we started using the central A/C in the house. When the compressor kicks on we get an even bigger dip in the lights. I have 200 amp service coming into the house. When I checked the amp reading on both hot legs coming in from the meter I never have seen peak amp readings above 65 - 70 amps when the A/C kicks on or if I fire up the D/C. I do see a momentary 5 - 7 volt drop in voltage on each leg though. Today I checked the amps and voltage on each leg w/ the A/C and clothes dryer running at the same time: found a continuous 65 amps on both legs and the voltage was down to about 107 volts. Normally w/o the A/C or dryer running the voltage is about 113 or 114 volts. This voltage drop must be the cause of the lights dimming, and it seems to be an excessive amount to me. My power comes from a pole mounted transformer that I share with my neighbor across the street. My lot used to have an old farm house that was torn down to build my house, so I suspect that the same transformer has been out there for some time. Any electrical types in the Creek have any insight on this or any ideas on how I might correct this issue?

Thanks,

Clay

[Von Bickley]

I would contact the Power Company. That voltage does seem very low to me. My voltage runs about 121 volts per leg.

[Rob Russell]

I'd agree - contact the power company. If you can recreate the 107 volt readings by turning on the A/C and dryer, I'd show them that. 107 is below spec. 110 or 115 is really the minimum appliances are designed for. When you fire up the dryer and A/C, try turning on a couple of stove burners too as if your wife were cooking dinner while a load of laundry was running - see what the voltage does then.

Our voltage is usually around 125.

Rob

[Clay Crocker]

Thanks for the input Von and Rob. I called the power company this morning, they are going to send someone out to look at my issue. I will see what they say.

Clay

[Clay Crocker]

Lineman from the power company was out. He said that they have to provide 120 volts plus or minus 5%, that would be 114 - 126 volts. While he was checking the meter he was getting about 113 volts, then the A/C kicked on and it went down to about 110 volts. He said that my transformer was a 10 KVA and is the smallest one that they have. He said that he has to "prove" to their engineers that there is a voltage problem before they will change the transformer, so they are going to put a chart recorder on my meter for several days to record any voltage dips. I will see what happens.

Clay

[Jim Becker]

Sounds like you want to be running your tools a lot over the next few days, Clay!!

[Greg Peterson]

My thoughts exactly Jim.

Put a good healthy load on your service. Lot's of A/C cycles, TS and D/C firings should get the engineers attention.

[Clay Crocker]

You guys read my mind!

[David G Baker]

Clay,
I had a similar problem with my power, it turned out to be the lug on neutral leg under the power meter was loose. The Utility company sent a guy out, he checked the house wiring and everything checked out fine but as a last resort he pulled the switch at the pole and checked the lugs at the meter. The two hot lugs were snug but the neutral was barely touching the wire. I have no idea how the lug was loosened. No problem since.

[Ken Fitzgerald]

Sounds like you want to be running your tools a lot over the next few days, Clay!!

My thoughts exactly Jim.

Put a good healthy load on your service. Lot's of A/C cycles, TS and D/C firings should get the engineers attention.

You guys read my mind!

Make sure that they cycle on/off....on all together....one off then on.....another one off/ then on again......You want a high average and you want surges that occur when they cycle on and off.

[Mark Hubler]

Might have them check the size of the wires from the pole to your house. My local power company refused to change the wiring enough though I upgraded the panel from 100 amp to 200 amp.

[Mike Henderson]

Clay,
I had a similar problem with my power, it turned out to be the lug on neutral leg under the power meter was loose. The Utility company sent a guy out, he checked the house wiring and everything checked out fine but as a last resort he pulled the switch at the pole and checked the lugs at the meter. The two hot lugs were snug but the neutral was barely touching the wire. I have no idea how the lug was loosened. No problem since.

I had an experience with a loose neutral, also. But one symptom of a loose neutral is that when the voltage on one leg (hot-to-neutral) goes down, the voltage on the other leg (hot-to-neutral) goes up. So the voltage hot-to-hot is maybe 240 but with the neutral floating, the split is not 120 hot-to-neutral on both legs - it varies as the load changes. When you load up one leg, that voltage goes down while the other less loaded leg voltage goes up. The sum of the two voltages still equals 240V.

If the voltage on both legs goes down at the same time when the demand increases (such that the sum is less than 240V), it's not a loose neutral (based on my experience). Note that to check for a loose neutral, you can't measure the voltage hot-to-hot. You have to measure each leg hot-to-neutral, preferably at the same time.

Mike

[Rob Russell]

Have your wife running laundry and cooking at the same time that you're playing with your machinery. That will definitely help the voltage drop.

[Travis Lavallee]

I look at these problems daily where I work. I work for the utility up here in the engineering department. Some of the possible problems will be that your feeder could be out of balance and you could be tapped of the more loaded phase. Also it could be a distance from the station issue and you are stuck on the feeder end. You can't do much to fix these other than complain to the utility, and upgradign the transfomer will not fix these issues, they will have to fix things on there end. If they find your feeder to have a low average <114V, this is when they will start to look at fixing it.

[Clay Crocker]

Well, the electric company came out and put a new transformer on the pole across the road (they did not even bother putting the chart recorder on my meter first), I guess the engineer did not need anymore proof than the Lineman's observations. Anyway, it has improved the situation. Voltage is up around 118 volts on each leg now (119.5 volts according to the Smart UPS on my computer) and there is very little drop in voltage when any of the larger loads come on. Still notice a very slight flicker in the house lights when the AC comes on but none when I turn on the DC or my TS. It seems like the voltage has gradually improved over the several days since the transformer was installed; not sure why it was not an instant change? Thanks for everyone's input on this issue.

Clay