open neutral and energy usage

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Re: open neutral and energy usage

Only thing I can imagine is that a problem on the premises caused the overusage and burnout. Somehow this problem must have corrected itself by burning itself out, or perhaps someone accidentally corrected it. It is hard to imagine though that with enough current to trip 60A breakers the problem would not be easily located.
 
Re: open neutral and energy usage

I see in your original post what the poco replaced but what did you replace with this work.If you replaced nothing then maybe you can file a complaint with your states utility watchdog, and pursue getting some money back from poco.
 
Re: open neutral and energy usage

I would think that an electrician had checked with an amp probe and voltmeter long before the poco was called.Why did they wait so long to get this solved ? currious as to what the meter did with the main breaker turned off.Something in this picture is wrong.
 
Re: open neutral and energy usage

Jim, you just said a mouthful. I would imagine that the electric utility would be required to test and or keep the meter for possible investigation (we do). :D
 
Re: open neutral and energy usage

Quote from Chevy they say now there bills have dropped by over 65%
any explanation of how the usage could change considering the problem was on the utility side of the meter.

Chevy as long as the problem is on the secondary side of the utility line it wouldn't matter if it where on the line or load side of the meter it would still have the same effect on the light bill.

Edited:On second thought if the lines where going together before the meter you could be right.


I agree with Charlie about the neutral and a lower light bill because of lower voltage.

But line #1 and line #2 shorting together would sure make that meter spin.

Ronald :)

[ December 19, 2004, 09:03 PM: Message edited by: ronaldrc ]
 
Re: open neutral and energy usage

ok senary at the meter base lets say line 1 line 2 shorted together at legs on customer side dead short high usage ground fault.

now at meter base line 1 line 2 shorted together on poco side no ground fault no high usage come on if thats the case the meter must be one heck of an instrument to stop all current flow and ground faults before entering the house
 
Re: open neutral and energy usage

and lets not forget the open neutral in this senary completly burnt off using the house piping as return path
 
Re: open neutral and energy usage

Chevy,

There are simply too many missing pieces in your story to give you an answer.

There was clearly something wrong, but the information you've provided is too distorted to positively say, "The problem is X, Y and Z."

Sorry that we can't help you. :)
 
Re: open neutral and energy usage

Chevy, Is there a possibility that the incoming poco lines had insulation damage where one leg leaked into earth near the copper pipe under the slab. In addition, is the isolated copper pipe bonded to the SE main equipment grounded bus?
Btw, what grounding method is used for the GES?

rbj, Seattle
 
Re: open neutral and energy usage

Chevy,her is my take of what happened.Neutral was lost ahead of meter,due to loss of neutral loads in the house are now going to receive a voltage in the 200+ volt range.This will occur because of common connection on neutral bus and high ohms on the ground rod.The circuit will now be from hot through load to neutral bus and back to another load to opposing phase.The loads were connected in parallel between the hot and neutral before the neutral was lost,now they are connected in parallel between the two phases.Parallel connection of the loads greatly reduces the resistance and now the voltage is also doubled.this will increase power usage and usually results in many burned up appliances. Depending on how much resistance is in the circuit and other factors such as how good of ground rod connection you have,how wet etc.,and is the neutral totally interrupted.
The service on a house is basically a large multiwire circuit.This happened to my house a few years back.My wife ran out of the house screaming the house is on fire,everything is blowing up.I was outside working on the car.I ran inside the house and looked,the light bulbs were very bright and some of them were exploding.I recognized the problem and rushed outside and cut off the main breaker,then went in the house and put out the fire in the carpet,caused by an exploding surge arrestor on my computer.I lost many appliances etc. but was in general very thankful that i was an electrician and at home at the time.If you put the pencil to it i beleive that you will find that in this scenario with a given resistance power usage increases 4x.
 
Re: open neutral and energy usage

canman,

Neutral was lost ahead of meter,due to loss of neutral loads in the house are now going to receive a voltage in the 200+ volt range.
Click to expand...
Parallel connection of the loads greatly reduces the resistance and now the voltage is also doubled.
Click to expand...
Not all loads will see an elevated voltage. Some will see a reduced voltage. It all depends on the combination of connected loads at the time the neutral connection is lost.

It is impossible for the voltage to be doubled across a load in an open neutral condition.


If you halve the voltage, power decreases by a factor of 4. Likewise, if you double the voltage, power increases by a factor of 4.

Take a 4500 watt water heater for instance.

It consumes 4500 watts at 240 volts.

It consumes 1125 watts at 120 volts. (4 times less.)

The resistance of the water heater does not change.
 
Re: open neutral and energy usage

I am with Peter on the open neutral thing. No way to exceed 240V. The 120V lamps and appliances would suffer mightily though. I saw this happen at a carnival, and I knew what was happening. Someone else did too because they got it fixed before serious damage was done.

And Peter, the truth is that the resistance of the heating elements changes with a lower voltage because the temperature of the nicrhome would be lower.
 
Re: open neutral and energy usage

Peter,then are you saying that the statement that the voltage in all parts of a parallel circuit will be the same is not true?And are you also saying that the resistance of a given number of resistances is not always less than the smallest one of the resistors in question when they are placed in parallel?Maybe you should try putting a few water heaters in parallel and then increase the voltage.Please help me understand.
 
Re: open neutral and energy usage

In the case of an open neutral in a circuit that has an unbalanced load, the increase in voltage, if any, always occurs on the side that has the higher resistance, that is, the side with the least load connected.
It would be offset by a drop in voltage, and a drop in power used, on the side with the greater load.

3wire3.gif


In this simplified example, the total normal load is 1440 watts + 480 watts for a total of 1920 watts. (Sketch A)

With the neutral open, the two loads are now in series, sharing the 240 volts.(Sketch B) The voltage across the 10 ohm load is only 60 volts, with 180 volts across the 30 ohm load.

Total power is now 360 + 1080 = 1440 watts, less than the normal power.

Ed
 
Re: open neutral and energy usage

ED,I totally agree with your statement,however the loads in question in the residential service will not become a series circuit until all paths but one have been destroyed.
 
Re: open neutral and energy usage

Cannan

if the neutral is lost every load on "A" leg will be in parallel and every load on "B" leg will be in parallel but if the neutral is open these two circuits will be in series with 240 volts accross this series circuit.

For example on "A" leg we have three 100 watt lamps in parallel which = 300 watts @ 120 volts
and on the "B" leg we have 10 100 watt lamps in parallel which = 1000 watts @ 120 volts

this would mean that leg "A" would have a load of 2.5 amps with a resistance of 48 ohm's

Leg "B" will have a load of 8.33 amps with a resistance of 14.4 ohms

The both of these circuits would result in 1300 watts total power usage with the neutral

Now lets open the neutral
the circuit now draws 3.8 amps @240 volts

The 48 ohm's on leg "A" now has 184.6 volts on it
and the 14.4 ohms on leg "B" now has 55.4 volts on it. this leaves
701.w + 213 =914 watts total.

You see as even with loads in parallel it would still result in the same formula.

even though the 300 watts of lamps would not last to long @ 184.6 volts :roll:

[ December 24, 2004, 02:32 AM: Message edited by: hurk27 ]
 
Re: open neutral and energy usage

And Peter, the truth is that the resistance of the heating elements changes with a lower voltage because the temperature of the nicrhome would be lower.
Click to expand...
True, but the cold resistance of a heating element or a light bulb is still a fixed value.

Is my water heater example incorrect? Ohm's law must surely still apply. :confused: When you apply less voltage, the element does not get as hot, therefore it has less resistance than it would at a higher voltage. [higher temp = higher resistance]. But isn't this offset by the lower voltage?
 
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