Replies

1. 
   fireball | Nov 14, 2003 07:31pm | #1

   Rob,

   Your voltage readings are fine.People sometimes expect to see exactly 110 or 120 volts when they use a digital voltmeter but those are only nominal values.The 125 volts to ground doesn't indicate that the transformer by your house is going bad,if anything just that it isn't heavily loaded.If you are having problems with bulbs not lasting it's more likely a bulb quality issue.The stronger the filament design,the longer they will last.A cheaply made filament gets fragile with heating and cooling cycles,then you slam a nearby door or walk on the floor above it and the vibration makes it go TING.Try using a "rough service" bulb as an experiment.

   Barry

2. 
   OneofmanyBobs | Nov 14, 2003 08:18pm | #2

   A small increase in the line voltage will drastically reduce the life of an incandescent bulb.  A small decrease will make it last a lot longer.  Most major appliances work fine in the range of 105 to 130, and somethimes even as low as 95 volts.  Assuming your meter is accurate, and few inexpensive meters are much better than 5% accurate at measuring AC RMS voltage, you're a bit higher than I like.  Probably within acceptable limits as far as the power company is concerned.  But, if your meter is reading a couple percent low, then you could possibly be at 130 which is too high.  If your incandescent bulbs are lasting less than 400 or 500 hours, I'd call the power company and ask them to come measure it.  Normal life should be something like 750 to 1200 hours, depending.  Its probably not a transformer problem, but there are taps they can use to adjust the voltage depending on where the problem lies.

3. 
   Stuart | Nov 14, 2003 09:22pm | #3

   The electric utility will probably say that as long as the voltage is within +/- 10% it's okay. That means 108-132 volts for a nominal 120, and 216-264 volts for a nominal 240. That said, you do seem to be at the high end of the range.

   Ask the utility to come out and put a voltage recorder on your service entrance for a couple days, to see if it goes up and down or if it's consistently high. If it stays high all the time, they should be able to adjust the voltage at their transformer.

1. 
   BillHartmann | Nov 14, 2003 09:45pm | #4

   10% is too high a range.

   I think that that the standard is +- 5% at the meter and +5,-7% inside the home (to allow for drops in internal wiring).

   And the design standard is 120 volts.

   Except in CA. Two years ago they allowed a slighly lower drop because of the power shortage.

   These numbers may not be right, but they are close. I tried a google and either found mentions of transients or reference to a standards book.

1. 
   rjgogo | Nov 14, 2003 10:54pm | #5

   Thanks for the replies,  I may have Comed check it as I have been experience pretty short life, sounds like it may be within spec but I will watch it and check it with another meter to double check the accuracy.  Looks like I should keep an eye on it.  I just wanted to make sure it was not to far over and it sound like it is approaching the border.  Thanks, Rob.

   Edited 11/14/2003 2:55:22 PM ET by rjgogo

2. 
   JohnSprung | Nov 14, 2003 11:06pm | #6

   Last time I asked the LADWP, they said their standard is +/- 5%.  That would put the top limits at 126 per leg and 252 for the pair.

   Buying bulbs rated for 130 volts will solve the problem.  If you have dimmers, dropping them a tad bit down from the max will work, too.

   -- J.S.

1. 
   DavidThomas | Nov 15, 2003 03:14am | #7

   As others have said. "120 volts" often isn't.  Note that when you have 5% more voltage, your lights bulbs, toaster and hair dryer put out 10.25% more power.

   Long-life light bulbs or 130-volt versions (same thing?) put out fewer lumens per kwh.  So you don't change so many but you pay more to the power company.  I don't have the packaging with me here, but something like 20% less lumens.  So, on average, you'll turn on one more light bulb for every 5 long-life ones used.  At my house, 1000 hours, 100 watts = 100 kwh = $8.36 to the electric Co-op for the life of a normal $1 bulb.  (so I use compact flourescents in any open fixtures that my wife doesn't complain about).

   For you, the choice would be:  6 long-life bulbs (let's say they last 1,000 hours at your voltage instead of 2,000 hours at mine) x 1,000 hours x 100 watts x $0.10/kwh = $60 to Con Ed plus 6 x $3 for the bulbs = $18 for a total of $78

   Or use 5 regular bulbs (fewer because they have more lumens each) but two sets for the shorter life to acheive 1,000 hours x 100 watts x $0.10 = $50 to Con Ed.  plus 10 bulbs at $1/each = $10 for a total of $60.  Both scenerios gave you the same lumens for the same time.

   Seems to me you are ahead dollars-wise to use the standard bulbs because of the greater lumens/watt.  And the standard bulbs are cheap and can be found on sale.   Long-life and 130-volt bulbs never go on sale.

   But every house has a couple of fixtures that are a pain to change and long-life bulbs would be great there.  Maintenance/janitorial catalogs always offer some really long-life bulbs (lousy lumens/watt) because 1) those bulbs get changed at union wages and 2) nobody likes getting out the 24-foot ladder to climb to the top of the school gym.

   Hoping my thought were illuminating,

   David Thomas   Overlooking Cook Inlet in Kenai, Alaska

4. 
   DavidThomas | Nov 15, 2003 03:22am | #8

   Oh yeah, another thought.  I've seen little discs that you place in the socket before the bulb that claim to length bulb life by many fold.  They have to be a half-wave rectifier that would clip/block the negative voltage in each cycle.  (Could they possibly just be a resistor?  Wouldn't that get too hot in the socket?)  Anyway, bulb-life goes way, way up but lumens plummets.   You'd never come out ahead except for cathedral ceilings with 30-feet-up-there fixtures (that should have allowed for compact flourescent reflector bulbs).

   Or maybe for a bed-side reading light where you really only want 5 watts of lights but can only find 15 and 40-watt medium-base bulbs.

   David Thomas   Overlooking Cook Inlet in Kenai, Alaska
1. 
   JohnSprung | Nov 15, 2003 04:00am | #9

   Probably a resistor -- a half wave rectifier would dim the bulb way down to an orange color and very little light. 

   As for the reduction in lumens you have with 130 v. bulbs, try an A/B comparison.  I find that my eyes adapt just fine to the slight difference, and I don't turn on more lights.  The spectral spikes of flourescents bother me a lot more than that, so I only use them to give burglars the impression that somebody's home.

   -- J.S.

2. 
   CapnMac | Nov 15, 2003 05:12am | #10

   really only want 5 watts of lights but can only find 15 and 40

   Sylvania has a 20w medium bas miniflood that works pretty good for that sort of application.  Downside is that the fool things run about $4-5 each.  They are tolerant of being on dimmers, too--the only downside to the medium based fluorescents.Occupational hazard of my occupation not being around (sorry Bubba)