blown lightbulbs

[rick hart]

Re: blown lightbulbs

You might try 130V lamps, assuming you haven't already tried them.

Still doesn't explain the noises you hear.....

 

[karl riley]

Re: blown lightbulbs

mm, 240V loads are not affected by a bad neutral, so turning them on tells you nothing. Then,if you turn on all the 120V loads, they may balance out so once again you get little or no info.

The best test would be to turn on all the 120V loads; then go to the panel box and turn off all but one of the A circuits (or B). Now you can check the voltages. If the A load still has normal voltage, this verifies the supply neutral is OK.

About going to Radio Shack and getting not the cheapest multimeter, but the cheapest one with min/max, you will be getting an accurate meter. The electronics are simple these days and cost little for the manufacturer. On the other hand, I have had to send an expensive Fluke back (Model 87) because the low part of the voltage scale was very inaccurate due to a design decision they made. I tested almost all the multimeters on the market when I was manufacturing gaussmeters which used the millivolt circuit. One of the cheaper ones gave me the best accuracy and reliability.

As for going to Radio Shack, many electricians think that they will have to spend a lot of money for an instrument they don't normally carry, and so they don't get it.

Karl

 

[lesliek]

Re: blown lightbulbs

exactly 2 weeks ago POCO out troubleshooting replaced underground supply to first TSF from distribution (previously 24 patches regards ground fault, replaced, then yet other utility dig clearly marked used mechanical and caused yet another ground fault- 2 meter sockets ajacent homes fused/fires after splice correction) Guy was TWO days to retirement. Was using this:

http://www.cpsc.gov/cpscpub/prerel/prhtml03/03167.html

He did NOT survive flash. Expect OSHA will cause CPSC to update notice eventually. Did not witness the event, just came upon the aftermath returning from a supply run.

not that it pertains to string, but thought I'd share as I happened upon the mention of the experience at the panel by the POCO mentioned here.

http://www.cpsc.gov/cpscpub/prerel/prhtml99/99100.html
http://www.cpsc.gov/cpscpub/prerel/prhtml05/05515.html

 

[hardworkingstiff]

Re: blown lightbulbs

Originally posted by mmoore:
The first leg read 123 volts but when he switched a switch on his meter to read the other leg there was an explosion and the meter was fried. He said this has never happened before and he couldn't explain it.

I would call this guys supervisor and tell him what happened and ask him for clarification on exactly what was being switched and what function it performed. How the device was hooked up, exactly. How it works. I think if you dig into what this machine was testing for it may help lead you to your problem. The POCO should not just abandon you (even if it is "not their problem").

 

[RCinFLA]

Re: blown lightbulbs

Usual bet it is bad neutral.

Shut down all the 120 v loads you can in the house. Find the highest amperage 120 v service breaker (likely in kitchen, at least 20 amp) load it near its max with toaster, hairdrier, or such. Go to breaker box and measure AC between neutral and L1 and neutral and L2 sides. If ground is good should not see more then couple volts difference between readings. If bad neutral it will be pulled to heavy load side.

Second most likely is power company installed wrong type transformer on pole.

Third, rare case, is if you are only service connection at the end of a long remote transmission line you can have an impedance transformation to higher voltage at end of lightly loaded line. Similarly, if there were power factor correction capacitors installed on power poles because of some heavy inductive user in you neighborhood that closed shop or moved away and the power company has not removed the PF caps on the line.