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-   -   900W and up trips breaker, Circuit draws power even with everything off... (http://www.diychatroom.com/f18/900w-up-trips-breaker-circuit-draws-power-even-everything-off-58494/)

jasonblu 12-04-2009 02:19 PM

900W and up trips breaker, Circuit draws power even with everything off...
 
Hi all,

I have narrowed down a nuisance tripping problem to this...

Symptoms and Actions:
Circuit Breaker No. 18 trips when I turn anything 900W or higher on. Regular lights and low power items dont trip it.

When I turn all the breakers in the house OFF EXCEPT No. 18, my Electric meter still spins showing a current draw EVEN THOUGH EVERYTHING IS TURNED OFF AND EVERYTHING IS UNPLUGGED.

I have confirmed that every outlet is unplugged and that the doorbell transformer is not part of this circuit, nor are there any "always on/hardwired" type water pipe or floor type heaters anywhere in the house.

I detached the hot and neutral from this circuit breaker and tested resistance between the two. I read 4 to 5 ohms. Interesting to note that when I turn the whole breaker off, every other breaker in the box reads at around 18 OHMS for the 15A and 20A circuites, and in the 80's for the higher amperage breakers. This confuses me - since I would assume, with all light switches off and all outlets unplugged you should read OPEN between all hots and neutrals. Guess I need to read up on my electrical basics.

I replaced the offending breaker with two different brand new. No change either time. It's not a weak breaker.

Seems to me I have a "partial" short between Hot and Neutral that is creating a 900W draw to ground which is not enough, apparently, to trip the breaker right away, but once I add another 900W or more, the 15A breaker trips.

If so, how do I methodically hunt down this short?

If its not a short to neutral, what is it?

Thanks you all!

jasonblu 12-04-2009 04:41 PM

*UPDATE* I think I may have found the Problem...
 
Further troubleshooting seems to reveal that the circuit ONLY "trips" under that 900W load if the GFCI that is in the loop in the bathroom is 'closed/reset'.

I tripped the GFCI, leaving that outlet cold/off, now I can put even 1800W on this circuit and it wont trip.

I took off the plate of the GFCI and pulled it away from the wall, all the connections 'seem' to be right...

Can a bad GFCI cause a constant 900W drop to neutral when set/closed?

Do I just replace this GFCI, or is this indicative of some bigger problem somewhere else in this circuit?

Yoyizit 12-04-2009 04:43 PM

Quote:

Originally Posted by jasonblu (Post 361238)
If its not a short, what is it?

15A @ 120v should trip at 1800w, so it seems you have a 900w load somewhere.
But, (120^2)/5 = 2900w, so that 5 ohm reading doesn't seem to make sense.
And 900w of incand. lamps would read about 1.3 ohms when cold.

How many watts does your electric meter read?
"The amount of energy represented by one revolution of the disc is denoted by the symbol Kh which is given in units of watt-hours per revolution. The value 7.2 is commonly seen. Using the value of Kh, one can determine their power consumption at any given time by timing the disc with a stopwatch. If the time in seconds taken by the disc to complete one revolution is t, then the power in watts is . For example, if Kh = 7.2, as above, and one revolution took place in 14.4 seconds, the power is 1800 watts. This method can be used to determine the power consumption of household devices by switching them on one by one."

AllanJ 12-04-2009 04:44 PM

If your breaker trips on 900 watts of known load, the unknown load is too big to ve phantom.

A phantom draw is due to capacitance (in thrun resultin g in a minue flow of current even though there is nothing connected in the circuit. Current is actually induced through the insulation of the wires in the Romex cable by the wires bein juxtaposed.

A small load such as a doorbell transformer will put enough load to make the meter turn slowly.

Remove the wire hot wire from the breaker and connect a small (at least 25 watt) incandescent light between the breaker terminal and the loose hot wire. If the light goes on, then there is a load on the circuit bigger than a doorbell transforemer and much bigger than phantom.

beenthere 12-04-2009 05:18 PM

Is another circuit fed off that GFCI.

If so. look at anything in your kitchen. that doesn't work when you trip the GFCI. Also, check outdoor lights and receps, they may have wired one to the GFCI.

kbsparky 12-04-2009 06:08 PM

Probably a piece of heat tape plugged into that circuit. The fact that the bathroom GFI controls it further confirms my suspicions.

Look under the house (basement/crawl space) for the culprit.

tpolk 12-04-2009 06:27 PM

the meter turning while house is turned off is built in by electric company to always make money for stock holders:laughing:

Billy_Bob 12-04-2009 06:55 PM

It is chilly lately. Do you have an electric space heater somewhere with the dial "turned off", but still plugged in?

Some electric heaters do not turn totally off, rather they will run when it gets pretty cold. The dial just reduces the temperature that they will turn on at.

So might try unplugging things like this in seldom used areas like basement, attic, etc.

Or do you have a water pipe heater? These keep the pipes warm and keep them from freezing. Under house in crawl space?

Check all over...

joed 12-04-2009 06:55 PM

Sounds like you have a load that you haven't found. along with Beenthere's checks I have few others. Is the bathroom ventilation fan working or stuck? Is there a heater in it?

Jim Port 12-05-2009 01:26 AM

Quote:

Originally Posted by Yoyizit (Post 361283)
15A @ 120v should trip at 1800w,

Breakers do not trip exactly at the amp rating, ie a 15 does not trip at 15.01 nor 15.25. They will hold above the rating for a period of time depending on the amount of overage. The greater the overage the quicker the trip, 40 amps very quickly, 16 will probably hold for an hour or more. All this is determined by the manufacturers trip curves.

jasonblu 12-05-2009 09:30 AM

Quote:

Originally Posted by Yoyizit (Post 361283)
15A @ 120v should trip at 1800w, so it seems you have a 900w load somewhere.
But, (120^2)/5 = 2900w, so that 5 ohm reading doesn't seem to make sense.
And 900w of incand. lamps would read about 1.3 ohms when cold.

Thank you Yoyizit. I confirmed that EVERY Light switch is Turned OFF (thereby removing all light filaments from the equation, right?) , and NOTHING plugged into any outlet, still get 4 to 5 ohms. Very strange. That's why I suspect that Hot is lightly touching Neutral somewhere.

Quote:

Originally Posted by Yoyizit (Post 361283)
How many watts does your electric meter read?
"The amount of energy represented by one revolution of the disc is denoted by the symbol Kh which is given in units of watt-hours per revolution. The value 7.2 is commonly seen. Using the value of Kh, one can determine their power consumption at any given time by timing the disc with a stopwatch. If the time in seconds taken by the disc to complete one revolution is t, then the power in watts is . For example, if Kh = 7.2, as above, and one revolution took place in 14.4 seconds, the power is 1800 watts. This method can be used to determine the power consumption of household devices by switching them on one by one."

I will have to get back to you on this one. Cant kill power to the house - wife and baby are home now. Very curious to see though.

jasonblu 12-05-2009 09:35 AM

Quote:

Originally Posted by AllanJ (Post 361284)

A small load such as a doorbell transformer will put enough load to make the meter turn slowly.

THIS is interesting. Thank you. I think that could be contribting to at least some of the turning. I will confirm (and disconnect) the doorbell later today to see if I still get turning.

Quote:

Originally Posted by AllanJ (Post 361284)
Remove the wire hot wire from the breaker and connect a small (at least 25 watt) incandescent light between the breaker terminal and the loose hot wire. If the light goes on, then there is a load on the circuit bigger than a doorbell transforemer and much bigger than phantom.

Oh, Ok. I will try that too. Thanks!

jasonblu 12-05-2009 09:37 AM

Thanks for the tip. I Just confirmed though. Nothing in the kitchen is on this circuit nor fed from this bathroom GFCI.

Billy_Bob 12-05-2009 09:38 AM

What circuit is the doorbell and doorbell transformer on?

Dishwasher?

Garbage disposal?

Water treatment system?

Furnace/electronic air cleaner?

jasonblu 12-05-2009 09:43 AM

Quote:

Originally Posted by Billy_Bob (Post 361579)
What circuit is the doorbell and doorbell transformer on?

Dishwasher?

Garbage disposal?

Water treatment system?

Furnace/electronic air cleaner?

I just confirmed - doorbell transformer is NOT on my problematic circuit 18, so, that is not what is causing the meter disk to turn even with everything off. I cant isolate WHICH one its on right now though - everyone is home using stuff. :(


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