Help! Lights flickering in 3 story home.

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ndpelectric

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I hope you guys can help me.

I went on a service call yesterday, to a house that has been suffering from some flickering lights, and sluggish appliances.

Whenever the microwave is turned on, the lights in the entire house become dim, and the microwave runs at half speed.

Also, when the dryer is turned on, the lights in the house become EXTREMELY dim, and the dryer takes twice as long to finish.

Same problems apply for the dishwasher and refrigerator.

The house is a 3 flat, converted into a single family home. The building still has 3 meters in the back, and 3 panels in the basement. While trying to diagnose the problem, we shut off the main breakers for the second and basement floors, and left ONLY the microwave breaker on in the first floor panel. Every other breaker in that panel was off.

The microwave circuit is a dedicated circuit, not sharing any neutrals with any other circuit. When we started the microwave, it STILL ran sluggish, and did not work properly.

We are sure now that the problem is not inside, but we still cannot figure anything out! Help us.

It is 120/240 single phase. 3 100amp panels with 3 100amp meters.

HELP ME PLEASE!!!!!
 
See if this helps: If any lights brighten when others dim, the problem is poor neutral continuity. If you only get some dimming, the problem is poor hot conductor continuity.

If the problem only affects one unit, it's between the meters and the unit's panel. If the problem affects all three units, it'e between the meters and the untility transformer.

Troubleshooting is all about the process of elimination. First narrow it down by making easy tests like above, then locating the trouble by eliminating where it isn't.
 
It's to late for this advice..
But please, next time, make sure you turn off circuits an/or disconnect any electronics in the house so you don't burn them up.
Step two, start at the panel with the main off and make sure you are getting proper power there, then work your way in or out as you need to.
It doesn't matter how big the house is, it's all the same stuff.
 
See if this helps: If any lights brighten when others dim, the problem is poor neutral continuity. If you only get some dimming, the problem is poor hot conductor continuity. ....
Click to expand...

Can you put a dimmer on the end of an extesion cord with a good Ground, and still apply your thougth, if no dimmer exists ? ?
 
Thanks for the quick responses guys.

We turned off all 3 panels, and checked the incoming voltage at the meter, and main breakers. All read 120V to ground and to neutral. When the first floor panel is activated, and the branch circuits are turned on, the voltage on the "A" phase reads 130V, while the "b" phase is barely 100v.

Could it be a poor connection at the meter bank?

It effects all 3 floors while something is running. Every light dims.

Our power company came out and checked the splice at the service head, and at the transformer.

No one else using the same transformer is having this problem.

What do i do?!
 
Sounds like a low voltage problem - I would ensure proper voltage at the mains of each panel. I had a similar one a while back on a 8-family. The service was underground, single phase 800 amp. Tenants were reporting that bulbs were burning dim & some stuff not working in some, but not all of the units.
I checked the main lugs at the disconnect & read under 100 volts line to neutral on one side.. Correctly diagnosed the problem on our side & then called the POCO. Utility comes out & detects a parallel fault on the laterals. Guess a neutral had shorted against a line wire under the parking lot. They got it fixed & only some bulbs had burned out - luckily no electronics were fried!
 
Forget my last post then. It will be a mechanical faliure - think along those lines. Maybe a fault on the feeder between meter & panel. Did you check voltage at the mains with all the breakers turned off? If the voltage is good until you turn on a load then it could be a wiring problem on the feeder end OR a loose neutral somewhere
 
When all main breakers are off, both phases read 120V to ground and neutral.

when a main breaker is turned on, and a branch circuit breaker is turned on, the voltage jumps around and light flicker.

There is no voltage on the neutral. I am stuck.

Could it be the power companies fault? Should they come out again?

The family has lived in the house for 20 years, and this is the first time anything like this is happening.

Maybe poor connection at the meter? Were all just confused. Thank you all again for the responses
 
081213-1939 EST

ndpelectric:

Use your voltmeter to get some quantative data. If all of your information is correct it would look like a primary problem on the utility transformer. But I sort of doubt that.

I have to assume that some lights are on both sides of the transformer center tap (neutral). As Larry said if you load one side of neutral and some lights dim and others brighten, then look for a neutral problem. But neutral should not have much to do with the dryer being slow to dry.

If the neutral is a low impedance, then loading one side of neutral should not have as much effect in dimming the lights on the opposite phase as the lights on the phase with the load.

Almost certainly the microwave is 120 V on one phase.

I would put your meter on one 120 phase, label this one A. Plug a 1500 W 120 V heater into phase A somewhere and record the voltage before and after adding the load.

Next put your load on phase B with the meter still on phase A. Make the same measurements.

Move your meter to the B phase and repeat the above measurements.

Ideally you should make these voltage measurements at the main panel. If you find an outlet somewhere on Phase A and connect your meter to this, and use a different circuit on phase A for the load, then this is roughly equivalent to making the voltage measurement at the main panel.

If the neutral is good (a low impedance), then a change of load on one phase should not have a large effect on the othe phase. The change should not be equal. 1/2 might be OK.

Give us some quantative data.

.
 
081213-1841 EST

You have at least a neutral problem. This means some lights will brighten and others dim. Draw the circuit for a center tapped secondary feeding two resistive loads. If the neutral is a low impedance, then the voltage on one phase when loaded will probably drop, but will not change the other side much.

Open the neutral, this is the extreme condition. Now you have a voltage divider across the 240 supply and as you change the load from equal to unbalanced then the center point of the loads will change relative to any of the transformer terminals. 120 + 120 = 240, and 100 + 130 = 230.

You may have some hot lead impedance prolems as well as neutral.

Lights on the 130 V side are going to get brighter. Those on the 100 V side dimmer.

.
 
Gar, I see where you are going with that. But if the neutral is NOT good - i.e., high impedance then IMO you have to start in on locating a fault somewhere...Could be line to line OR line to neutral. Could be an open neutral on one of the feeders, if its happening on each panel where voltage is good until a load is present.
I would start to think the service or feeder conductors would be suspect. Is this an overhead or underground service? IMO you have an open neutral somewhere.
I had an overhead service change once where the lineman told me, " The service must have had a good ground. " When I asked him why he replied "Because the neutral is burned open in the weatherhead up here." By this time I had the new service built & was already energized... I never knew it, and neither did the HO's. BUT if there is no ground at the service & you lose a neutral then you can expect voltage problems.
Keep up the good detective work.
 
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Lots of good advice here already but I'll throw in my two cents worth. Flickering and dimming is almost always a bad connection somewhere. When trouble shooting you always have to start with "what do I know?"Never ever assume anything!! Sometimes a complicated problem can seem over whelming and leave one with the "I don't have a clue" feeling, but if you stop and ask yourself "What do I know about this" you will realize that that even on the most complicated problems you can add a whole bunch of stuff to that list. Get out your meter, find out some things you know and like others here have said, Divide and simplify.
 
081213-2041 EST

Kdawg67:

When you have one phase voltage increase and the other decrease by a large amount, as in this case, then there is at least a neutral problem.

The original statement was that all lights dimmed. Unless all lights are on the same phase as the load change causing the lights to dim there is no way all lights dim with a neutral problem.

That there is also slowness to dry in, what I assume, is a 240 V heated dryer implies additional hot wire problems.

If all circuits from all main panels exhibit the dimming from a load on only one panel, then the problem is before the three main panels.

.
 
Thank you guys again,

Should I try to ground out the incoming neutral? Would this show whether the neutral is poor coming in from the power company, or poor inside?

Also, there has been no major electrical changes in the house in 20 years. Everything worked fine for years, and stopped one day.

Im pretty sure the problem is on the load side of the panels. After testing a single circuit with everything else off, I can clearly see that the power supplied the branch circuit is corrupted....Right?

Confusing problem here. I cannot get any readings in the home that would lead me in a certain direction. The whole house seems effected. That information leads me away from any problem in 1 branch circuit.

Thank you so much for your help.
 
081213-2134 EST

ndpelectric:

I suspect that you have not had a lot of troubleshoot experience or much training in electrical circuit theory.

We shall assume first that the neutral is bonded to the ground bus somewhere near, in, or about the main panels. That there is a grounding electrode conductor (GEC) to something that is being used as the grounding electrode. Maybe a ground rod, maybe the incoming water supply.

If you have a clamp-on current meter put this around the GEC. Turn off all main breakers, or equivalent. The current should be near zero.

Turn one main breaker on, one branch circuit breaker on, and all loads on it off. Then to this circuit connect a 1500 W 120 V heater, about 12 A. How much current flows thru the GEC? If it is near 12 A, then you have an open neutral. If half this, then a high resistance in the neutral.

Tonight the residual current on my home GEC is 80 MA and adding a 10 A load it increases to 110 MA. Putting it on the opposite phase causes a reduction. Then went back an my residual had changed to 40 MA instead of 80 MA. There is a moderate load on the system and I do not know the distribution or phase angles. 30 MA change for a 10 A load change indicates that the ground resistance is in the ballpark of 300 times greater than the neutral resistance. My grounding electrode is about 150 ft of 1.25" copper pipe to the street. The street pipe may extend my ground electrode to my neighbor. A path length of maybe 400 ft to their main panel and between our main panels is probably 150 ft of neutral wire. In my case about 75 ft of 0000 copper to the pole transformer.

.
 
ndpelectric said:
Thank you guys again,

Should I try to ground out the incoming neutral? Would this show whether the neutral is poor coming in from the power company, or poor inside?

Also, there has been no major electrical changes in the house in 20 years. Everything worked fine for years, and stopped one day.

Im pretty sure the problem is on the load side of the panels. After testing a single circuit with everything else off, I can clearly see that the power supplied the branch circuit is corrupted....Right?

Confusing problem here. I cannot get any readings in the home that would lead me in a certain direction. The whole house seems effected. That information leads me away from any problem in 1 branch circuit.

Thank you so much for your help.
Click to expand...




This sounds like a very easy problem to fix. You should call an electrician. He could find the problem very quickly.;)
You have a main phase out. The screwy electric when something is turned on or off. That is caused by current from the good phase running through your elements in the water heater. To the other phase.
:cool:
 
If the neutral is there from the utility, then any grounding or bonding issues shouldn't create a voltage difference between phases...

Is this an overhead or underground service? Also, did the utility offer to look any further on their end? Did you show them the voltage you were reading when you had the panels turned on? Having a load on or not can make a difference to narrow it down between the POCO's end or yours.

IMO Loose connections would get you some intermittent problems, but this dimming thing makes me still think you've got a line-to-line or line-to-neutral fault somewhere between the transformer & your main.
 
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