Light bulbs are constanly burning out

I'd start by calling your utility. They have monitoring devices they can plug into your system that'll record voltage fluctuations from low voltage to spike. If they exist, it then becomes a matter of finding the cause, which could be anything from too small a transformer on the pole, an inadequate drop loop, wiring issues internal to the building or a device that you or a neighbor are using.

You may end up talking to the condo or apartment management, but I suspect they might not be real responsive.

Good luck.

Has someone there measured the line voltage? If not, that would seem to be the logical first step. If the voltage is too high, that would certainly explain the frequent bulb burn-outs, if not the breaker trips, and perhaps the power company could do something about it.

Regards,
-- Al

The good news is that light bulbs are much more sensitive to overvoltage than most other electrical equipment. They are giving you a warning...like the canary in the coal mine. You should get the problem fixed.

Nick_sr,

I would suggest you contact the landlord or building manager.

The problem could be a loose service entrance neutral conductor.

Have you ever noticed all of a sudden some lights get brighter at times while other go dim?

First call should be to an electrical contractor. The electrician will check line to neutral voltages at the main service. The electrician will determine if the problem is on the load side or line side of the meter/s. And if on the line side of the meter/s he will contact the utility company's service department.

Heres an interesting side story: A few years ago I replaced all the switches and wall plugs in the house because we changed the color to white. This place was built in 1979, so the originals were a bit different than what is available today. I did not buy the "pemium" ones at home depot because I needed so many. Ever since this, it has been very common to blow a light bulb upon flicking the switch if you do it too fast. I can even blow them on demand if I use the switch accordingly. Turning it on gently... no problem.

Did they use less than good quality bulbs to save on construction costs?

I have this issue in Austin. My voltage is about 127 volts. I buy 130v bulbs from Home Depot....

I have this issue in Austin. My voltage is about 127 volts.
09-10-09: Jfrech

127V is too high... For residential customers the utility company is supposed to keep the voltage with-in (+ or -) 5%. 120V being the base line.

You should contact your utility company and ask them to check your incoming voltage. It may be a simple fix of moving the taps on their transformer to lower the voltage.

Jea48 and/or Almarg,

Can I check the voltage myself with a multimeter? If so how?

Abucktwoeighty,
To save money the construction company simply didn't supply any lighting fixtures at all!

I just checked my voltage again with a multimeter 124.7 volts....

(Nick_sr make sure you know what your doing, I just set my meter to volts, selected the range properly and stuck the leads in - BE CAREFUL)

Can I check the voltage myself with a multimeter? If so how?

Yes. Set the multimeter to read AC Volts, on a scale such as 0 to 300 volts or some such number that will assure it won't be driven past the upper limit of the scale. Make sure that the test leads are connected to the proper jacks on the meter for making an ac voltage measurement on this scale.

WITHOUT TOUCHING THE METAL PROBE PINS AT THE END OF EACH TEST LEAD, insert one lead into one of the two vertical slots on an ac outlet, and the other lead into the other vertical slot. The meter will then indicate the line voltage.

While you are at it, also measure between the shorter vertical slot (which is ac "hot"), and the ac safety ground opening on the outlet (the one that accepts the circular third prong on an ac plug). That should indicate the same voltage as you measured between the hot and neutral terminals.

Then measure between the longer vertical slot (ac neutral) and ac safety ground. That should measure 0 or very close to it.

Then measure between each of the two vertical slots and the screw which holds the faceplate on. You should get the same two readings as when you measured between each of the vertical slots and the ac safety ground prong.

If any of these additional measurements are not correct, it indicates that there is an open connection or a miswire somewhere.

Regards,
-- Al

Al,

I measure 124.5 volts, and the measurement between each vertical slot and the ground read 124.5 and 3v.

124.5 is within the +/- 5% range suggested by jea48.

What now? The reading is on the high-end. Will the voltage change during the course of the day. I took the readings in the early afternoon, this not exactly peak hours.

Nick -- Yes, let's see what it does at other times during the day and night, although higher demand would figure to lower rather than raise the voltage (due to increased losses in the wiring), as you appear to realize. And I'll defer to the comments Jim (Jea48) will most likely offer on the 3 volt offset between neutral and safety ground -- he is more knowledgeable about that kind of thing than I am.

Regards,
-- Al

Can I check the voltage myself with a multimeter? If so how?

Agree with with Al...... But just remember the voltage reading will only be for that moment in time.

I suggest you talk to the other tenants in the 4plex.
See if they are having the same problem with light bulbs as you are.

I asked a question in an earlier post if you noticed if any incandescent light bulbs suddenly get brighter than normal.
With a loose service neutral conductor connection this is typical. The service neutral conductor carries only the unbalanced load back to the source, the utility transformer.

Example, say all Line 1 (L1) to service neutral loads equal 20 amps and all Line 2 (L2) to service neutral loads equal 20 amps. Then 0 amps will return to the source on the service neutral conductor. The two loads are in series with one another. If the loads are constant and do not vary the service neutral conductor could be disconnected and the two loads would continue to operate just fine.

But what if L1 to neutral load increased to 30 amps and L2 to neutral load remained at 20 amps. If the neutral has a good electrical connection back to the source then 10 amps will return on the neutral to the source.

Some simple calculations..... Lets keep it simple.... purely resistive loads. E = I x R

L1 to neutral load 30 amps. Find R (resistance in ohms)
120V / 30 = 4 ohms

L2 to neutral load 20 amps.
120V / 20 = 6 ohms



Here would be a worse case example. The service neutral is completely open, not connect somewhere between the neutral bus at the electrical panel and the source (utility transformer).
L1 to neutral bus loads and L2 to neutral bus loads are in series with one another.

Current is the same in all parts of a series circuit. Find I (current, amps)

L1 loads, 4 ohms total.
L2 loads, 6 ohms total.
R1 + R2 = Rt = 10 ohms

240V / 10 ohms = 24 amps

Find voltage drop across L1 to neutral bus loads.
E = I x R
24 amps x 4 ohms = 96 volts......

Find voltage drop across L2 to neutral bus loads.
24 amps x 6 ohms = 144 volts.....

The above example would be the extreme that could happen in the event of a total loss of a service neutral connection for the given loads.
A loose or corroded service neutral connection will have the same effect but because of resistance within the bad connection the voltage drop variables will change due to the amount of unbalanced load current placed upon it. And just to muddy the water the service
neutral to earth connection integrity becomes part of the equation as well. Most utility companies connect the neutral at the utility transformer to earth ground as well.

So basically in the case of a loose or corroded service neutral conductor where an unbalanced load is present at the electrical panel the Line with the bigger load will have a Line to neutral voltage lower than half the Line to Line voltage, and the other Line to neutral voltage higher than half of the Line to Line voltage. If the balanced load voltage is say 123V Line to neutral, (246V Line to Line), then one might easily see in an unbalanced load condition one side with a voltage of 115V and the other side 131V. And again it all depends how big the unbalanced load is and how loose/corroded the service neutral connection is.

Now you can see why incandescent bulbs could become brighter when the refrigerator kicks on.

Nice explanation, Jim. Thanks!

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.

If so, meaning that losses in the hot side of the wiring are small compared to the losses in the neutral run, the voltage at the service panel for that line would be the 124.5 measured at the outlet + 3 = 127.5 volts.

And if not (if connection integrity is good for all of the neutral path between service panel and outlet), there is presumably also a 3V drop in the hot side of the wiring. That would mean that the voltage at the service panel for that line would be the 124.5 measured at the outlet + 3 x 2 = 130.5 volts.

In either case, these numbers provide added credence to the possibility you have suggested.

Does that all sound right?

Regards,
-- Al

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.
>>>>>>>>>>>>>>>>>>>>

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

Al and Jeff,

Sorry, I went a bit awol this week, it was crazy at the office.

I did find the time to contact the utility company. They said exaclty what Jeff recommended. Call an electrician and if he finds a problem on the utility's end then they will reimburse the cost of the electrician.

They also suggested to contact other neighbhours (not my fellow condo dwellers). To see if they have similar problems with bulbs.

So there it is.. Thank you guys for your helpful feedback it is truely appreciated.

One final note, I placed an order today for a new pair of Quicksilver Mid-mono monoblocks. So I hope I can resolve this issue before I take delivery.

Cheers and thanks again!

Nick