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Posted by Jeff Wisnia on June 21, 2007, 12:53 pm
H wrote:
>
>>
>>>In my breaker box, I have two 40A breakers side by side. One is for the
>>>A/C, one is for the electric dryer.
>>>
>>>Seemingly simultaneously, both of them experienced a loss of power
>>>(around
>>>11V) on one leg. Thus, neither the dryer nor a/c work.
>>>
>>>Can anyone imagine how this could happen, seemingly simultaneously?
>>>
>>>H
>>
>>I assume you have two 40A double pole breakers side by side, is this
>>correct? 11V L1 to L2? 11V L1 or L2 to N? Please provide some more
>>details.
>
>
>
> Yes, there are two 40A double pole breakers side by side.
>
> On both, at the breaker, it's 240V on both.
>
> At the other end of the line, it's around 80V (combined) on both. One leg
> has 127V, the other measures between 11V and 18V.
>
>
>
You still aren't telling us specifically where you are putting your
voltmeter leads to measure those voltages.
And, are you using an "electronic" voltmeter subject to displaying
voltages developed across its input impedance by microamp sized
capacitively coupled currents, or are you using a lower impedance analog
meter, not subject to showing so called "phantom" voltages?
Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.
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Posted by mike on June 21, 2007, 1:52 pm
> H wrote:
>
>
> >>>In my breaker box, I have two 40A breakers side by side. One is for the
> >>>A/C, one is for the electric dryer.
>
> >>>Seemingly simultaneously, both of them experienced a loss of power
> >>>(around
> >>>11V) on one leg. Thus, neither the dryer nor a/c work.
>
> >>>Can anyone imagine how this could happen, seemingly simultaneously?
>
> >>>H
>
> >>I assume you have two 40A double pole breakers side by side, is this
> >>correct? 11V L1 to L2? 11V L1 or L2 to N? Please provide some more
> >>details.
>
> > Yes, there are two 40A double pole breakers side by side.
>
> > On both, at the breaker, it's 240V on both.
>
> > At the other end of the line, it's around 80V (combined) on both. One leg
> > has 127V, the other measures between 11V and 18V.
>
> You still aren't telling us specifically where you are putting your
> voltmeter leads to measure those voltages.
>
> And, are you using an "electronic" voltmeter subject to displaying
> voltages developed across its input impedance by microamp sized
> capacitively coupled currents, or are you using a lower impedance analog
> meter, not subject to showing so called "phantom" voltages?
>
> Jeff
>
> --
> Jeffry Wisnia
> (W1BSV + Brass Rat '57 EE)
> The speed of light is 1.8*10^12 furlongs per fortnight.- Hide quoted text -
>
> - Show quoted text -
I wish manufacturers would mention the Phantom Voltage issue with
electronic multimeters. It would save a lot of needless frustration.
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Posted by Jeff Wisnia on June 21, 2007, 3:53 pm
mike wrote:
>
>>H wrote:
>>
>>
>>
>>>>>In my breaker box, I have two 40A breakers side by side. One is for the
>>>>>A/C, one is for the electric dryer.
>>
>>>>>Seemingly simultaneously, both of them experienced a loss of power
>>>>>(around
>>>>>11V) on one leg. Thus, neither the dryer nor a/c work.
>>
>>>>>Can anyone imagine how this could happen, seemingly simultaneously?
>>
>>>>>H
>>
>>>>I assume you have two 40A double pole breakers side by side, is this
>>>>correct? 11V L1 to L2? 11V L1 or L2 to N? Please provide some more
>>>>details.
>>
>>>Yes, there are two 40A double pole breakers side by side.
>>
>>>On both, at the breaker, it's 240V on both.
>>
>>>At the other end of the line, it's around 80V (combined) on both. One leg
>>>has 127V, the other measures between 11V and 18V.
>>
>>You still aren't telling us specifically where you are putting your
>>voltmeter leads to measure those voltages.
>>
>>And, are you using an "electronic" voltmeter subject to displaying
>>voltages developed across its input impedance by microamp sized
>>capacitively coupled currents, or are you using a lower impedance analog
>>meter, not subject to showing so called "phantom" voltages?
>>
>>Jeff
>>
>>--
>>Jeffry Wisnia
>>(W1BSV + Brass Rat '57 EE)
>>The speed of light is 1.8*10^12 furlongs per fortnight.- Hide quoted text -
>>
>>- Show quoted text -
>
>
> I wish manufacturers would mention the Phantom Voltage issue with
> electronic multimeters. It would save a lot of needless frustration.
>
That would only help people who RTFM. <G>
Jeff
--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.
|
|
Posted by William Underhill on June 20, 2007, 10:16 pm
H wrote:
> In my breaker box, I have two 40A breakers side by side. One is for the
> A/C, one is for the electric dryer.
>
> Seemingly simultaneously, both of them experienced a loss of power (around
> 11V) on one leg. Thus, neither the dryer nor a/c work.
>
> Can anyone imagine how this could happen, seemingly simultaneously?
>
> H
Only way I can imagine this happening simultaneously is if one
transformer phase on the utility pole went out. Have a look at your
power meter - is the disk turning at all? If you feel safe doing so and
have a decent voltmeter, you could open the service panel and check for
voltage between the bus bars. Check each bus bar to the neutral line,
and to each other; there should be 115 volts between each phase and
neutral, and 230 between the two bus bars.
If there's not, you have a problem. My own inclination would be next to
check at the terminals right on the master breaker, if they're
accessible (not easy on some designs), on the house side; if you still
have a loss of voltage, then I'd check on the other side of the breaker.
If the problem exists on both sides of the breaker, call the hydro
company. If the supply side is good but the service panel side isn't,
call your favourite electrician.
WARNING: Don't do this if you are at all unsure of what you're doing!
Wear electrical safety gloves rated to at least 1000 V, long-sleeved
shirt and trousers (sleeves rolled down), rubber-soled boots and stand
on a piece of rubber mat while you do this. Have someone stand by with a
3 or 4-foot length of wood - 2x2 will do nicely; if you have an
unfinished (i.e., not varnished or painted) wooden cane, even better.
Their job will be to knock you clear of the panel if something happens
and you accidentally contact something.
Sorry if this is stuff you already know, but better safe than sorry -
and it may be of use to others.
Yours aye,
W. Underhill
(who, the other day, proved the axiom that familiarity breeds contempt
and as a result was bitten by 440 V on an auxiliary relay...)
--
"Take sides! Always take sides! You may sometimes be wrong - but the man
who refuses to take sides must *always* be wrong! Heaven save us from
poltroons who fear to make a choice!" R.A. Heinlein, "Double Star"
--
Main homepage: http://members.shaw.ca/fog.locker/
SCA homepage: http://members.shaw.ca/uilliam/
LiveJournal: http://www.livejournal.com/users/jackytar/
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Posted by H on June 20, 2007, 10:21 pm
>H wrote:
>> In my breaker box, I have two 40A breakers side by side. One is for the
>> A/C, one is for the electric dryer.
>>
>> Seemingly simultaneously, both of them experienced a loss of power
>> (around 11V) on one leg. Thus, neither the dryer nor a/c work.
>>
>> Can anyone imagine how this could happen, seemingly simultaneously?
>>
>> H
>
> Only way I can imagine this happening simultaneously is if one transformer
> phase on the utility pole went out. Have a look at your power meter - is
> the disk turning at all? If you feel safe doing so and have a decent
> voltmeter, you could open the service panel and check for voltage between
> the bus bars. Check each bus bar to the neutral line, and to each other;
> there should be 115 volts between each phase and neutral, and 230 between
> the two bus bars.
>
> If there's not, you have a problem. My own inclination would be next to
> check at the terminals right on the master breaker, if they're accessible
> (not easy on some designs), on the house side; if you still have a loss of
> voltage, then I'd check on the other side of the breaker. If the problem
> exists on both sides of the breaker, call the hydro company. If the supply
> side is good but the service panel side isn't, call your favourite
> electrician.
>
> WARNING: Don't do this if you are at all unsure of what you're doing! Wear
> electrical safety gloves rated to at least 1000 V, long-sleeved shirt and
> trousers (sleeves rolled down), rubber-soled boots and stand on a piece of
> rubber mat while you do this. Have someone stand by with a 3 or 4-foot
> length of wood - 2x2 will do nicely; if you have an unfinished (i.e., not
> varnished or painted) wooden cane, even better. Their job will be to knock
> you clear of the panel if something happens and you accidentally contact
> something.
>
> Sorry if this is stuff you already know, but better safe than sorry - and
> it may be of use to others.
>
> Yours aye,
> W. Underhill
Well, I do know what I am doing around a breaker panel, but I had an
electrician anyway testing the breakers. They are working perfectly. Full
power on the business leads of the double breaker. The other end (at the
dryer and A/C) is where the problems manifest themselves.
One thing of possible import: I am having a new room added to the back of
the house, and an electrician ran a new wire into the breaker panel, though
he did it rather blind (he could not see exactly where the drill came out in
the basement.
It seemed to me that had he hit the 240V line, sparks (or something) would
fly. None of that happened. But, if he had nicked both 240V lines, would
that explain the power loss (which is not total)?
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