Ahhh HELP ME!!!

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dwellselectric

Inactive, Email Never Verified
:mad: Okay I have a problem that I can't seem to find the answer to so perhaps someone would be able to help me. There is this house that I have worked on and the homeowner called me up because of a problem that they where having with lights pulsing. So I went there thinking it was a dimmer... Little did I know that it was all the lights in the house that where on dimmers. I checked the panel and made sure everything was tight and took readings everything seemed normal. I went out to the meter opened it up tighted up everything nothing was loose. Checked the over head connectors nothing seemed wrong with them. I had Nstar come down to double check and they said everything was normal nothing was wrong. The house has two ground rods so I know its not a bad ground. I can't figure out why the lights on dimmers are pulsing. Its not constant its just every once in awhile. Anyone have any ideas that might help me? Please I tried everything!!!:mad:
 

Oakey

Senior Member
Location
New Jersey
This may sound odd but a service call I diagnosed for the same problem was traced to continously running appliance motor.
 

1793

Senior Member
Location
Louisville, Kentucky
Occupation
Inspector
dSilanskas said:
Regular dimmers lights are not low voltage and they have been working for about five to six years now....

Don't know but worth asking: Are the lights on the dimmers incandescent or compact fluorescent?
 

K2500

Senior Member
Location
Texas
Oakey said:
This may sound odd but a service call I diagnosed for the same problem was traced to continously running appliance motor.

I was thinking the samething, or the nieghbor's got one hell of an A/C condenser:D
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
dSilanskas said:
The house has two ground rods so I know its not a bad ground.

The grounding system has absolutely nothing to do with this, nor virtually any other electrical problem.

Are these by any chance X10 controllers? All kinds of weird things happen with them.
 

brian john

Senior Member
Location
Leesburg, VA
Is this flicker lights dimming regularly then returning to normal for a period of time (motor starting inrush voltage drop?), or is this a constant flicker (loose conductor).

NOT NECESSARILY IN ORDER OF IMPORTANCE.

1. Two ground rods does not mean or do much for this issue.
2. Using a min max multimeter connect the meter at the service and watch for meter variances from steady state voltage.
3. Measure current at the same time. If you have flicker but no related current increases as there is VD then issue is upstream and may be a load by someone elese on the distribution system.
4. Measure voltage with the min max function at selected points throughout the house.
5. Check for ground current on GEC, EGCs, water pipe, at ground electrodes, with an eye on possible neutral issues.
6. Measure the current of L1, L2 and neutral simultaneously, the reading should be "0" amps.
7. Is this on L1 and L2 (more likely a neutral issue) or is it isolated to one of the "HOT" legs (this could be a loose energized conductor).
8. Check for thermal issue with all connections and circuit breakers utilizing a non-contact thermometer.
9. Perform *Fall of Potential (FOP) test across distribution components, the meter, main CB ECT.
10. NOTHING PERSONAL against the utility, BUT do not necessarily believe what they say. Many (not all) of these linemen know less that one would think. For that matter when trouble shooting I listen to everything anyone has to add to the topic, but do all investigations myself even if it was already looked at, especially if it has been looked at.

This does not cover all possible trouyble shooting ideas and others may have further ideas to add. PERCERVIENCE, the problem is there you just have to keep looking.


As little as 3.0 VAC drop Line to Neutral can result in noticeable light flicker

* from a another post
Fall of Potential test (FOP)

With any electrical procedures that involve making measurements with energized conductors care must be taken and proper PPE must be worn

Fall of potential is a measurement of voltage drop (VD), in a circuit that is the voltage lost to heating due to resistance in the circuit. To perform this test one measures voltage from the line side connections to the load side connections, the readings are typically in the millivolts range and require load.

For example with a 3-phase Circuit Breaker that is nuisance tripping, measure current (balance loads are beneficial but not necessary), then measure from the line bus to the load conductors (if bare conductor is exposed), for all three phases. If one phase has a higher that average millivolts reading, then try to isolate this issue. Measure from line bus to the Circuit Breaker bus stab, if all 3-phases have millivolts readings that are the same (or close to the same) measure from the bus stab to the load side conductor termination connector (through the Circuit Breaker), if all these readings are close, next take measurements from the load side termination connector to the load conductor. In this case you can determine if it is a line bus connection issue, bad Circuit Breaker or a load conductor termination issue. Any accessible portion of the device can be tested in this method.
 
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brian john

Senior Member
Location
Leesburg, VA
I put this together for another forum, just some thoughts on light flicker.


Light flicker (dimming and restoration of light to near preflicker level) of lights from motor inrush) is a byproduct of several factors and generally is difficult to over come.

AC motor loads (in particular compressors) but all motor loads have inrush currents. These inrush currents result in voltage drop in the branch circuit, panel bus, service laterals, utility transformer and possibility the utility HV feeders.

Flicker is in addition user dependent; some people are more susceptible to flicker. For some reason flicker seems to bother women more that men (based upon personal experience).

A Voltage Drop (VD) as little as 3 volts on a nominal 120 VAC system is noticeable (by me), 2.5% VD.

We have had cases were the VD was all a byproduct of primarily single phase 120 VAC loads, in these cases we were able to put the lighting on L1 and all the motor loads on L2, the HVAC compressors were something the homeowner had to live with. This minimizes the flicker.


To test for this VD and resulting flicker to determine the source of the inrush, use a min max amp clamp and min max multimeter at the main service watch the lights(it may take two workers) and correlate to the meters.
 

dwellselectric

Inactive, Email Never Verified
Brian John I already did all those things voltage is not below normal and all connections are tight. No clue what is wrong. No new products in the house and the lights dim get bright than dim again but its not constant its just at certain times.. No idea wtf is wrong!!! Going crazy now:mad:
 

stickboy1375

Senior Member
Location
Litchfield, CT
What brand dimmers, Did you try removing some of the dimmers to see if the problem went away? I cannot believe with dimming lights that it is not a bad neutral...
 
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Paul Allen

Electrical Contractor
Location
Middleburg Florida
Occupation
Electrical Contractor
Just my 2 cents, but taking voltage readings with a recording voltmeter is needed. sounds like problem is in the service voltage coming in. I had a similar problem, checked everything in the house to no avail. Told the utility they had a bad connection, of course they didn't, until it finally got bad enough they had to go up and look at it. Had a bad connection at the transformer. Would not show up when there was a light load, but come home and turn on the stove, A/C and let the neighbor connected to the same x'former do the same, BINGO.
Good luck!

Paul Allen
FL Master Electrician
 

brian john

Senior Member
Location
Leesburg, VA
YOU DID EVERYTHING ON THE LIST?

Everyone overlooks things DOUBLE CHECK all of the above.

What type of tester did you use?

If available as noted above use a high speed recording meter.

We are missing/overlooking something!
 
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tom baker

First Chief Moderator & NEC Expert
Staff member
Location
Bremerton, Washington
Occupation
Master Electrician
The eye is very sensitive to voltage related flicker. Look for whats changed, more load on the POCO transformer? Any specific time of day?
 

gndrod

Senior Member
Location
Ca and Wa
Paul and Tom are keyed into the external source as the likely culprit. Is there a possibility that a loose neutral in the neighbor's service could have an effect through common plumbing metal pipe grounding electrodes? Just a thought from Paul's comments. On second thought the neighbor would have experienced problems by now. rbj
 
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elvis_931

Senior Member
Location
Tennessee
Have you considered checking the power factor? Back when I was in school I knew a lot more about this, but at present time I am kinda fuzzy on it. It could be that you have poor power quality coming in to that particular house. Power factor can be conditioned by adding capacitance, I remember that!. Some one else may be able to elaborate.
 
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