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Old 08-26-2015, 01:58 PM   #1
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Default Dimming lights

I had a call recently to inspect some dimming lights in a home. It started when they purchased a new coffee espresso machine to replace their old one. When the unit is turned on and is hearing the water and the Central A/C unit is running the lights in the house start dimming. 90% of the house is LED lamps and they do not show quite as much dimming. The worst of the dimming is a 10 or 12 lamp incandescent chandelier in the dining room off the kitchen. The espresso machine causes dimming regardless of which 20A small appliance branch circuit is used in the kitchen. All the lighting is on separate circuits from the kitchen counter receptacles. All feeder hots & neutrals appear tight and unoxidized. All branch circuit connections in all panels are tight. At the panel that the kitchen receptacles are fed from, the SABC feeder leg drops 2 volts upon turning the espresso machine on. The opposite leg increases 2 volts at the same moment. The dimming is much less noticeable when the central A/C is not running. The legs at the service and panels are at 115V & 117V. Any thoughts on the cause of this?
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Old 08-26-2015, 02:08 PM   #2
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Investigate the neutral for corrosion, poor connection, etc.
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Old 08-26-2015, 05:04 PM   #3
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Like Vintage said, Neutral could be loose in the panel, at meter outside, at point of attachment, or even at the pole.
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Old 08-26-2015, 05:10 PM   #4
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Originally Posted by Vintage Sounds View Post
Investigate the neutral for corrosion, poor connection, etc.

Is it most likely an issue with the neutral of the circuit that is dimming? Both the dining room chandelier with incandescent lamps and the kitchen lighting circuit with LED lamps have the dimming issue. The thing is that these two lighting circuits are desperate circuits.
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Old 08-26-2015, 05:11 PM   #5
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Like Vintage said, Neutral could be loose in the panel, at meter outside, at point of attachment, or even at the pole.

You feel that it's the main neutral somewhere rather than the circuit neutral?
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Old 08-26-2015, 06:22 PM   #6
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What is the current draw on the machine?



Since it is less noticeable when the AC is off, I suspect it's system wide and maybe/probably on the the POCO end.

If there are multiple panels involved, run a #12 extension cord to the main service panel and see it it corrects the problem.

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At the panel that the kitchen receptacles are fed from, the SABC feeder leg drops 2 volts upon turning the espresso machine on. The opposite leg increases 2 volts at the same moment.
2 volts doesn't seem like much but the up/down voltage is typical of a compromised neutral.

Last edited by 220/221; 08-26-2015 at 06:26 PM.
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Old 08-26-2015, 06:44 PM   #7
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What is the current draw on the machine?



Since it is less noticeable when the AC is off, I suspect it's system wide and maybe/probably on the the POCO end.

If there are multiple panels involved, run a #12 extension cord to the main service panel and see it it corrects the problem.



2 volts doesn't seem like much but the up/down voltage is typical of a compromised neutral.

The machine is 14.5A. Good idea; I'll try the extension cord.
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Old 08-26-2015, 06:56 PM   #8
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Neutral, Neutral, Neutral.

Think possibly a problem from the pole to the panel, maybe even corrosion at the meter connections.
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Old 08-26-2015, 08:35 PM   #9
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Neutral, Neutral, Neutral.

Think possibly a problem from the pole to the panel, maybe even corrosion at the meter connections.
Or at the sub or the sub feeder.

Plugging it in to the main panel will narrow it down.
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Old 08-26-2015, 09:06 PM   #10
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Wow, if that puppy draws 14.5 amps methinks these folks are just way too addicted to caffeine...

I do like the idea of going straight to the panel with an extension cord, and if everything is good that way, I would consider a dedicated espresso receptacle.

There's got to be a good joke in here somewhere, ...
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Old 08-27-2015, 12:57 PM   #11
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Almost every time I hear symptoms like this, it is a bad N connection on poco side of meter...
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Old 08-27-2015, 01:33 PM   #12
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I think everyone is barking up the wrong tree when they keep saying neutral. If that was the case, other lights would also get brighter. In this case you're either looking for a bad service HOT conductor, undersized/corroded service drop/lateral, or an undersized/overloaded pole top transformer. The neutral is fine, and it's the hot legs you need to look at. Something service equipment/service side related on the hots.
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Old 08-27-2015, 02:15 PM   #13
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Way back in my apprentice days, when industrial and commercial was slow, we would wire homes, and some of them, (especially in the higher end neighboorhoods) would have us run 500mcm drops, in an effort to eliminate flicker, when high amperage loads would in the home would cycle on/off.
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Old 08-27-2015, 02:49 PM   #14
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Quote:
Originally Posted by MDShunk View Post
I think everyone is barking up the wrong tree when they keep saying neutral. If that was the case, other lights would also get brighter.
Maybe they are but it is not as evident or visable like the chandilier?


Do you think the 2V plus on one side and 2V minus on the other leg is normal/inconsequential?

I'm not sure at what voltage it becomes a problem. We have all seen the neutral related 10-20 volt change and it's enough to dim/brighten the lights and turn off the TV.

@ 2V? I have no clue
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Old 08-27-2015, 02:58 PM   #15
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The reason I always run Chandeliers on its own circuit , 10 or 12 bulbs . What is the wattage ? It can add up quickly .

Coffee Maker is a big draw , like to see its own circuit .

I agree that it is not likely a neutral problem .




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Old 08-28-2015, 06:14 PM   #16
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Does the chandelier still dim
If you bypass the dimer ?
I have come across simulair problems
Caused by non linear response
From the dimers control circuitry.
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Old 08-30-2015, 09:32 AM   #17
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Quote:
Originally Posted by dmxtothemax View Post
Does the chandelier still dim
If you bypass the dimer ?
I have come across simulair problems
Caused by non linear response
From the dimers control circuitry.

I bypassed the dimmer and the dimming continued.
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Old 08-30-2015, 09:34 AM   #18
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Quote:
Originally Posted by pete87 View Post
The reason I always run Chandeliers on its own circuit , 10 or 12 bulbs . What is the wattage ? It can add up quickly .



Coffee Maker is a big draw , like to see its own circuit .



I agree that it is not likely a neutral problem .









Pete

I would say that they are 25W bulbs; I will check when I am back there on Monday. The coffee maker was basically on its own circuit as it is on the kitchen SABC and nothing else was plugged into that circuit.
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Old 08-30-2015, 09:57 AM   #19
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Old 08-30-2015, 12:07 PM   #20
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....

That's all you have to say?
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