Light bulbs are constanly burning out

Al, (Jea48 I answer you below)

Here are the readings from throughout the day:
1pm: 124.5v
6pm: 123.0v
10pm: 120.0v
12am: 124.0v
5am: 125.3v
9am: 124.3v

Given the above, it would reasonable to expect that the voltage could reach above 126v.

Jea48,

...if any incandescent light bulbs suddenly get brighter than normal...

The only time the lights dim is when my wife switches on the kettle. The kettle is plugged into the same breaker as the plug that the lights in the main living area are connected to.

If I take a reading on that plug the voltage drop is from 123.8 to 110. (measured across both vertical slots). However, if I measure from the short vertical to the ground then it reads 116v. If I turn off the kettle the reading goes back to the 123.8.

In regards, to other big consumers, I have regular fridge a wine fridge, dishwaser etc... I have never noticed a diming or brightning of the lights as these appliance switch on of off. I live in open concept condo, so I can hear when these appliance switch on and off.

Breaking News!!! As i am writing this, my surge protector just tripped, I measured the voltage and it is at 126.5v.

I guess I should contact my utility company!

One last point regarding my fellow tennants, the bulbs in the hallway are constantly burning out. I have not explicitly raised this issue with any of the neighbours but I will bring it up in our next condo meeting. I am quite sure that this is shared problem.

Thanks for the help it is greatly appreciated!

The only time the lights dim is when my wife switches on the kettle. The kettle is plugged into the same breaker as the plug that the lights in the main living area are connected to. If I take a reading on that plug the voltage drop is from 123.8 to 110. (measured across both vertical slots). However, if I measure from the short vertical to the ground then it reads 116v. If I turn off the kettle the reading goes back to the 123.8.

Nick -- How many watts does the kettle consume? That should be indicated on a label somewhere on it.

Regards,
-- Al

Nick -- How many watts does the kettle consume? That should be indicated on a label somewhere on it.

1500 watts

The only time the lights dim is when my wife switches on the kettle (1500 watts). The kettle is plugged into the same breaker as the plug that the lights in the main living area are connected to. If I take a reading on that plug the voltage drop is from 123.8 to 110. (measured across both vertical slots). However, if I measure from the short vertical to the ground then it reads 116v. If I turn off the kettle the reading goes back to the 123.8.

Jim, it sounds like he's got a bit more than about 1/2 ohm of resistance between the service panel and the outlet, in each of the two runs (hot and neutral). Seems a little high, unless the runs are unusually long.

But in any event, that would mean that all of the voltage readings Nick reported (measured at the outlets) are probably understating the voltages at the service panel, by around 1.1 volts per amp of current draw. And since those measurements are highish to begin with, it sounds like something really is amiss on other side (the outside) of the service panel.

So I agree that a call to the power company definitely seems warranted.

Regards,
-- Al

So if he has a 3V differential between ac neutral and ac safety ground at the particular outlet he measured, let's make the following rough assumptions:

-- 100 feet of wiring from the outlet to where those two lines are bonded together at the service panel.

-- Negligible current flowing through the safety ground wiring.

-- Wire resistance of 1.6 ohms per thousand feet (corresponding approximately to 12 gauge wire). Which would mean 0.16 ohms for 100 feet.

That would mean, if the resistance through the path is what it should be, that he has 3/0.16 = 18.75 amps flowing through the neutral wiring on that line.

Sounds kind of high, suggesting that perhaps the resistance is higher than it should be somewhere in the neutral run.

Al,

Voltage drop, (VD), would come into play I would think for the 3 volt difference of potential between the neutral and the equipment grounding conductor. And for VD to exist we need a connected load across the hot and neutral conductors of the branch circuit. The greater the load the more VD. ( NEC recommends that the VD drop for a combination feeder / branch circuit should not exceed 5%)

The 3 volts Nick measured from the neut to the grd could of been the result of connected loads on the branch circuit and VD.

We do not have the whole picture though just what wiring method was used for Rick's Condo. I can only assume each condo has its own electric meter. Are the meters all located together in a common meter bank? Is the main disconnect, (breaker), for each condo electrical service outside by its respective meter? If the main disconnect is outside by the meter then I assume the service neutral was connected to earth there. I assume the electrical panel is inside the condo unit. If that is the case then 4 conductors were ran from the disconnect to the electrical panel. 2 hots, 1 neut, and 1 equipment grounding conductor.

At the electrical panel a separated isolated neutral bar is needed and a separate equipment ground bar. What is the distance the main disconnect is from the electrical panel?
So without knowing how rick's condo is wired it hard to give a good answer regarding the 3 volts.

I believe though, from memory, NEC says at the end of a branch circuit there shall not be more than 1 ohm of resistance between the neutral and equipment grounding conductor. To check naturally the branch circuit would need to be de energized and any loads disconnected from the branch circuit.

3 volts....... It could just be his meter registering phantom voltage. High resistance digital volt meters are notorious for giving erroneous readings at times when not connected across a load. Jmho you can't beat a good old analog meter.
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If I take a reading on that plug the voltage drop is from 123.8 to 110. (measured across both vertical slots). However, if I measure from the short vertical to the ground then it reads 116v. If I turn off the kettle the reading goes back to the 123.8.
09-12-09: Nick_sr

VD is definitely more than 5%....

I would check around for a good electrical contractor. Preferably a commercial/industrial electrical contractor. The contractor will send out a service driver electrician with trouble shooting experience and find and fix the problem. One hour of labor probably around $100 - $150 bucks.... If the problem is by chance on the Line side of the electric meter the electrician will call the utility company's service department.

Jim