parallel grounding and light dimming
- Thread starter rybrama
- Start date
- Status
- Location
- Illinois
- Occupation
- retired electrician
Re: parallel grounding and light dimming
No, there are no problems with parallel grounds.
No, there are no problems with parallel grounds.
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
Re: parallel grounding and light dimming
Are you looking into an actual problem, with a house that has lights going dim, and asking whether the grounding electrode system might be the cause? If so, I agree with Don. This would not be the cause.
So if you are looking into an actual problem, if you give us more of the symptoms, perhaps we could help with the troubleshooting.
Are you looking into an actual problem, with a house that has lights going dim, and asking whether the grounding electrode system might be the cause? If so, I agree with Don. This would not be the cause.
So if you are looking into an actual problem, if you give us more of the symptoms, perhaps we could help with the troubleshooting.
- Location
- Bremerton, Washington
Re: parallel grounding and light dimming
The grounding is not a system as the premise wiring system is. Normally there is no current.
Multiple paths reduce the resistance.
The grounding is not a system as the premise wiring system is. Normally there is no current.
Multiple paths reduce the resistance.
Re: parallel grounding and light dimming
This is a actual problem. I installed a 200 ampere new GE panel and new underground service entrance cables, 1 1/2 years ago. I inspected the main lugs on the panel and in the meter socket on both the line and supply sides and found no loose connections. When a heavier load e.g. washing machine, ac, microwave is applied the lights will dimm slightly. I took a voltage test with true RMS meter and could not detect a drop in the voltage.
Thanks for any insightas I am perplexed,puzzled and pondered.
This is a actual problem. I installed a 200 ampere new GE panel and new underground service entrance cables, 1 1/2 years ago. I inspected the main lugs on the panel and in the meter socket on both the line and supply sides and found no loose connections. When a heavier load e.g. washing machine, ac, microwave is applied the lights will dimm slightly. I took a voltage test with true RMS meter and could not detect a drop in the voltage.
Thanks for any insightas I am perplexed,puzzled and pondered.
allenwayne
Senior Member
Re: parallel grounding and light dimming
You wrote that you checked meter and panel main lugs are tight can we assume that all branch circuit neutrals are tight as well as all breakers.
Also was this a service upgrade or new construction ? Herein might be the answer.
How was home originally circuited were the dimming lights part of what you call the heavier load circuits.
Try swapping phases and see if lights still dim.Without more facts each reply will be a shot in the dark
You wrote that you checked meter and panel main lugs are tight can we assume that all branch circuit neutrals are tight as well as all breakers.
Also was this a service upgrade or new construction ? Herein might be the answer.
How was home originally circuited were the dimming lights part of what you call the heavier load circuits.
Try swapping phases and see if lights still dim.Without more facts each reply will be a shot in the dark
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
Re: parallel grounding and light dimming
When anyone anywhere in any home or any other type of facility starts a large motor, the lights are going to dim. No exceptions. The dimming might be so slight that your eye cannot detect the difference, but it happens. It might happen so fast that a voltage meter will not detect it, but it happens. It happens because we do not use superconducting materials in household, commercial, or industrial wiring.
The motor draws a large starting current, which causes a lowering of the voltage of the power source (i.e., because of impedance internal to the source). During that short interval, every load in the facility will have a lower voltage. The lighting load responds to that lower voltage by putting out less light.
The problem gets worse if the wires to the large motors (your washing machine, for example) are too small, or if the wires to the lights themselves are too small. It also gets worse if the internal impedance of the service transformer is too high. Loose connections could also be the cause. I worked on a problem in an apartment building in which all the lights would dim whenever the elevators moved. The tenants blamed the management, and the management blamed the utility.
Do you recall any of the wiring details (choice of wire size and type, length of wiring runs)?
When anyone anywhere in any home or any other type of facility starts a large motor, the lights are going to dim. No exceptions. The dimming might be so slight that your eye cannot detect the difference, but it happens. It might happen so fast that a voltage meter will not detect it, but it happens. It happens because we do not use superconducting materials in household, commercial, or industrial wiring.
The motor draws a large starting current, which causes a lowering of the voltage of the power source (i.e., because of impedance internal to the source). During that short interval, every load in the facility will have a lower voltage. The lighting load responds to that lower voltage by putting out less light.
The problem gets worse if the wires to the large motors (your washing machine, for example) are too small, or if the wires to the lights themselves are too small. It also gets worse if the internal impedance of the service transformer is too high. Loose connections could also be the cause. I worked on a problem in an apartment building in which all the lights would dim whenever the elevators moved. The tenants blamed the management, and the management blamed the utility.
Do you recall any of the wiring details (choice of wire size and type, length of wiring runs)?
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: parallel grounding and light dimming
The voltage sag that common dwelling motors cause when they start only lasts for a second or three. Most of the time the center of our vision will not detect the fluctuation of lumen levels. However, our night / peripheral vision detects this well. I think it is part of our old survival skill set that is hard wired in our brains. The lumen fluctuation is detected as a relative motion or passing of a shadow that triggers our "flight or fight" response system at some level. For this reason, I use the edge of my vision, when I'm trouble shooting this type of complaint.
I'm not trying to dismiss the light dimming. I can't judge that, as I haven't seen it.
If you have other voltmeters, try them. Their response times and sample rates may well be quicker than the True RMS unit you used the first time.
From this statement, I'm making three assumptions: </font>
- <font size="2" face="Verdana, Helvetica, sans-serif">There are three different circuits going to three different areas of the dwelling.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">Two circuits are 120 Volt and the AC circuit is 240 Volt.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">These three circuits are not used for the general area lighting.</font>
The voltage sag that common dwelling motors cause when they start only lasts for a second or three. Most of the time the center of our vision will not detect the fluctuation of lumen levels. However, our night / peripheral vision detects this well. I think it is part of our old survival skill set that is hard wired in our brains. The lumen fluctuation is detected as a relative motion or passing of a shadow that triggers our "flight or fight" response system at some level. For this reason, I use the edge of my vision, when I'm trouble shooting this type of complaint.
I'm not trying to dismiss the light dimming. I can't judge that, as I haven't seen it.
If you have other voltmeters, try them. Their response times and sample rates may well be quicker than the True RMS unit you used the first time.
Re: parallel grounding and light dimming
thank you all for your responses , they are greatly appreciated.
The project was an extensive remodel and new addition, approx 40' x 16 with full basement to the rear of a baswmented ranch house.
The wiring for the project was 12nm and 12 THHN solid and stranded for most circuits. Dryer and A/C was 10 THHN. I used 14/3 for switchlegs to the high hats on two circuits. Refirigeratir, washing machine, microwave are dedicated circuits. Disposal and dishwasher are on one circuit. I also have not more than 7 receptacles on a circuit. The master bath has two GFI circuits, with a separate circuit for the fan,heat light and shower light.
The utility company was called a few months back and their response was, you guessed it , not our problem. I know for a fact that the utility had to replace one of their service laterals when the customer and a few neighbors lost one leg of the service. Thank you once again
thank you all for your responses , they are greatly appreciated.
The project was an extensive remodel and new addition, approx 40' x 16 with full basement to the rear of a baswmented ranch house.
The wiring for the project was 12nm and 12 THHN solid and stranded for most circuits. Dryer and A/C was 10 THHN. I used 14/3 for switchlegs to the high hats on two circuits. Refirigeratir, washing machine, microwave are dedicated circuits. Disposal and dishwasher are on one circuit. I also have not more than 7 receptacles on a circuit. The master bath has two GFI circuits, with a separate circuit for the fan,heat light and shower light.
The utility company was called a few months back and their response was, you guessed it , not our problem. I know for a fact that the utility had to replace one of their service laterals when the customer and a few neighbors lost one leg of the service. Thank you once again
LawnGuyLandSparky
Senior Member
Re: parallel grounding and light dimming
This is one of those things that just happens and you can't do anything about it, and the customer isn't satisfied with that answer and never will be.
Once I did a bathroom remodel. Old switch / combo receptacle on a local 15a convenience circuit. After remodel, GFCI on a 20a circuit with the light, totally new circuit.
H/O swore that the light never dimmed before when using the blowdrier, and now it does. Also swears the old light with the built-in shaver receptacle never caused the light to die either. And why can't I have an outlet in the new 6-light golfball chrome strip?
I told her she's mistaken and only THINKS the light never dimmed before, as then it was on a circuit with at least 8-10 other area receptacles and it was only 15 amperes. Now it's a 20 and dedicated to the bath. (At the time, I wasn't even required to run a 20, and it was only company policy that I run a new circuit at all.)
I suggested she plug that hairdrier into ANY other rteceptacle in the house and sure as I stand here, every light on that circuit will also dim.
You can't please everybody.
This is one of those things that just happens and you can't do anything about it, and the customer isn't satisfied with that answer and never will be.
Once I did a bathroom remodel. Old switch / combo receptacle on a local 15a convenience circuit. After remodel, GFCI on a 20a circuit with the light, totally new circuit.
H/O swore that the light never dimmed before when using the blowdrier, and now it does. Also swears the old light with the built-in shaver receptacle never caused the light to die either. And why can't I have an outlet in the new 6-light golfball chrome strip?
I told her she's mistaken and only THINKS the light never dimmed before, as then it was on a circuit with at least 8-10 other area receptacles and it was only 15 amperes. Now it's a 20 and dedicated to the bath. (At the time, I wasn't even required to run a 20, and it was only company policy that I run a new circuit at all.)
I suggested she plug that hairdrier into ANY other rteceptacle in the house and sure as I stand here, every light on that circuit will also dim.
You can't please everybody.
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