May 28, 2005
Engineering Department
VAC, Part 3
I did some more exploration of the local electrical power situation I outlined in my previous two postings. (Part 1 and Part 2.)
I drove to another block fed by a different phase of the same three-phase distribution lines that feed my building. After a couple of times around the block, I spotted an apartment building with an outdoor outlet, so I parked and walked up to test it. Unlike the night before, this one had power: at almost exactly 120 volts too. So not all phases were affected.
I drove around the remaining block on the third phase until I spotted a guy watering his front lawn. I wasn't looking forward to trying to explain my purpose—this is serious geek territory—but I got out of the car and walked up.
"Excuse me. I...I live in the next block, and we're having trouble with our electricity. Are you having any trouble with yours?" If he was, or even suspected he was, I'd have an easier time getting his cooperation.
"No."
"Well, I'm trying to figure out how far it spread...how many people are affected." I pulled out my digital multimeter; I had already spotted an outdoor outlet. "Do you have an outlet where I could check the voltage?"
"Go right ahead," he said waving to the outlet. "We usually get 127 volts."
Thank you, brother.
"Well," I responded, "I've been getting 137."
I walked up and plugged in.
"122 volts," I read off. "So you're fine."
He suggested it was a problemn with the transformer, and I explained why I didn't think so. We spent a few more minutes discussing it, then I thanked him and left.
So, it's only my block. That means it will be harder to rally a crowd to pester ComEd to fix this.
On the other hand, maybe they'll fix it this weekend, when the down time won't bother people as much. We'll see.
2 Comments
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Hi! I am enjoying the ongoing quest to fix your electrical service. I am a distribution/transmission operator, and as such, I work with those directly responsible for fixing probles such as yours. 135V is indeed WAY too high, and it's not a matter of ComEd WANTING to fix it. It is a violation of standards that can threaten public safety.
Most every piece of equipment is made for 110 to 115 VAC. The American National Standards Institute (ANSI) requires that voltage be made available to residential customers at 120V +/- 5% -- which yields a range of 126V to 114V. On any feeder line, especially those over three miles long, voltage on the feeder line gradually decreases as the cumulative load on the feeder line increases. This is called "line drop." Because of line drop, power must be transmitted at a high enough voltage that the last house on the line gets at least 114V. Consequently, power is often transmitted at an initial value of 126V. US homes receive an average of 122.5V. Approximately 99% receive more voltage than they need.
I would guess you are either close to a Capacitor Bank, which looks like this https://fireflydigitalmedia.com/images/capbank.jpg or a substation. Either way, the best thing to do is find out if there is a District Engineer or Local Office nearby where the maintenance crews and repairmen work out of. Contact the engineer there, and let him know about your voltage problems, and that you know that your neighbors have similar problems. This will show that it's not your tranformer. Also, let him know that you have had damage, you may be able to receive some compensation. Finally, if you have a Board of Public Utilities, they can be very helpful!
Sorry, that should be http://fireflydigitalmedia.com/images/capbank.jpg