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Light flickering/diming problem

6K views 46 replies 11 participants last post by  martingale2012 
#1 ·
I have moved into this house for 9 months and this problem keeps bugging me.

the house had a 100A panel when we moved in. and as soon as we moved in, we found that whenever equipment like garbage disposer, shop vac, power drill, mitter saw and air conditioner kicks off, all the lights inside the house blinked for a fraction of second.
the blinking caused by garbage disposer is less serious than it caused by air conditioner compressor. My guess is that compressor takes more current than the GD and anything else.

So we upgrade our panel to 200A, the blinking problem persists, but when we switch on GD, it doesn't blinks this time, while air conditioner still cause it to blink, just a little bit better.

So I get my plumber who installed my air conditioner here, we measured the current when a/c kicks off, it's 12A when started and 9A when running, far less than the 30A circuit breaker that supply the compressor.

Then I get PECO changed the line coming into the house, the problem persists!

Then two electrician came separately, they each inspected the connection from the meter to the panel, and everything was confirmed tight. We put an extra ground wire from the panel to my waterline, the problem persists!

I checked with my neighbor and he doesn't have an issue with that.

I plugged a lamp line directly to the main power line that coming into the panel, and when my air conditioner compressor kicks off, the lamp blinks.

I'm really tired of this and nobody can figure what's going on here.

anyone can save me??? it's really a headache.
 
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#27 ·
I know I'm late to this conversation, but I had the exact same symptoms as the OP. Lights dimming when a medium to large load drew power. I had an older house with a 60 amp service. I upgraded to 200 amp service with all new wiring, new panel, new can and new service entrance wires right out to the transformer.

Lights were dimming all the time especially when the 3.5 ton AC kicked on. I checked everything, no one could find the problem. I just lived with it.

Little did I know that the transformer was a 10kW, way undersized for my loads. I spoke with the POCO and they agreed that I was under served. A week later and they installed a new 25kW and problem solved.

Go out to your transformer and look for a large number on it. Standard residential transformers are either 10kW, 15kW or 25kW.
 
#5 ·
hi jbfan
thanks for the reply. but 2 things prevent me from believing this.

1. my c/b for a/c is 30Amp, so it's more than enough for a/c to kick off.
2. if that's the reason for a/c, why it also happends to my my shop vac and mitter saw, they all plug into a 20amp outlet.
 
#20 ·
Question for the OP... are the lights dimming, as in the intensity drops momentarily then is restored, or are they flickering, as in going out then coming back on?

Dimming is a symptom of voltage drop generally seen when a large motor starts; flickering is a symptom of a loose connection that is exacerbated when a large current passes through.

Which is it?
 
#21 ·
Hi househelper. it blink quick quickly, but with the helps of all the electricians and contractors in my house, I can say that it only dims, as in it just get dim for a fraction of second, and DOES NOT get brighter after that.

I heard that if it get dim then brighter, it could be an unbalanced neutral.
 
#32 ·
martingale2012 said:
Hi Dan

I took 2 pic of the transformer but cant see any identification on it.
a technician from peco came yesterday and said it's PERFECT normal and same stuff happen at his home.. I just cant believe how these people are thinking about it. I will call peco today and try to get a spec.

and there're 3 more house between me and transformer. i'm the last one in the line.

headache!
I would say lights dimming slightly (especially when the a/c comes on) is perfectly normal and is to be expected. But if every appliance you use makes your lights flicker, you have a problem somewhere.

How far do you think you are from the transformer? If you've got a great length of wire between your service and the transformer, that could explain some of your problems.
 
#3 ·
Hi Joe

I think there's somewhere loose, but just I have tightened everywhere that we can think of loose, still it blinks.
where else do you think can be loose? I'm trying to get PECO here again to tighten up everything.

and YES my A/c has a dedicated 30A circuit breaker for its own, it's a 30Amp orange line all the way to compressor.

Appreciate your help.
 
#8 ·
I'd say a loose connection is possible. Just confirming tight isn't enough. If the feeder wires are aluminum, they should be removed, the wires and the lugs cleaned, and an oxide inhibitor added before putting it all back together.
 
#9 · (Edited)
I

I checked with my neighbor and he doesn't have an issue with that.

I plugged a lamp line directly to the main power line that coming into the panel, and when my air conditioner compressor kicks off, the lamp blinks.

I'm really tired of this and nobody can figure what's going on here.

anyone can save me??? it's really a headache.
Martingale... That's pretty interesting.... did i understand that you tested that lamp upstraem from your main?????

I'm not a sparkie... so just wondering guessing.... if it could be in your meter pan or even with the POCO supply and transformer... could you be at the end of the transformer line.... or a bad split bolt/clamp on your neutral.....

Does it occur late at night when neighbors on your transformer are not on load???

EDIT: Also did your technician have a good fluke that records highest A draw.

Interesting....:huh:
 
#10 ·
Thanks MTN
Yes, I plug the lamp into the feeder line before coming into the panel.

Yes, I'm at the end of the line and there's 2 other house in front of me before the transformer. the blinking happened not only at night. it happened all time round.

How do I find a bad split bolt?
and my technician used a clamp meter to measure the current feeding to the compressor when it kicks off, it read 12A.
it is similar to this one here
http://www.homedepot.com/p/t/202521...gId=-1&storeId=10051&N=5yc1vZboff&R=202521277

do you mean the peak may be more than 30A but we were not able to read it using the clamp meter?
 
#14 ·
He got professional input from Jbfan, and dismissed it.

Put a hard start kit on the a/c. See if that solves the problem with the a/c.

If it fixes the problem with the a/c, you are done. If not, then you can chase all the other possibilities.
Oso.... Just honest curiosity.... would that solution be consistant with:

1) Only a 12A startup draw by A/C

2) Flickering on all circuts with GD, shopvac, other loads creating same flickering symptom.

Best

Peter
 
#18 · (Edited)
Martingale, When Jbfan says supply house, he doesn't mean Home Depot.
You need to call around and find it today. Check their business hours. A lot of Electrical supply houses are not open on the weekend.

Peter, I don't mean to ignore your questions, but I think the confusion caused by "exploring" sometimes detracts from getting the problem fixed.
Especially if someone is attempting to step through the problem, one step at a time. We can hold the exploration discussion later.
 
#19 ·
Martingale, When Jbfan says supply house, he doesn't mean Home Depot.
You need to call around and find it today. Check their business hours. A lot of Electrical supply houses are not open on the weekend.

Peter, I don't mean to ignore your questions, but I think the confusion caused by "exploring" sometimes detracts from getting the problem fixed.
Especially if someone is attempting to step through the problem, one step at a time. We can hold the exploration discussion later.[/QUOTE]

Oso.... Just a different approach..... My use of "exploring" means exploring for a solution that explains and solves (diagnozes) the problem consistant with the facts supplied by the OP (specifically lights flickering unassociated with startup of the ac compressor and a A reading well below V compromising draw...which the A draw issue may be explained by a faulty reading).... rather than just replacing /installing parts that may or may not be the solution.

You probably do know something I don't ...in why the hard start would solve flickering on other circuts that occur unassociated with startup of the compressor..... but I'm not sure why that explanation detracts from solving the problem... I would think it would only help.

I'll admit, it sure seems likely that a hard start might be beneficial to the issue, especially as it concerns the flickering at startup of the AC... I just don't understand why it would be a sufficient fix as it relates to the flickering unassociated with the AC..... maybe the OP has left out some factors/data,or maybe it's a different issue?

Best:)

Peter
 
#25 ·
Martingale....

We all have some varying opinions.... I tend to think it's good in that we compare notes, ask questions, and finally figure it out....IMHO

What really makes me wonder is that you said you somehow jumped a light before your main (upstream from your main) (and downstream from your meter) and you got your flicker there also. To me, that seems indicative that your problem lays upstream of your main.... in your meter pan... service wires, or transformer delivery.

You did say that you had the POCO put in new service wires... are you sure, or was that just when they hooked up your service drop. Did they have to put in a new meter and pan when you upgraded to 200A.?

My experience with POCO field crews is that they are not necessarily top notch electricians (I actually don't know if they have to be lisenced). They perform their routine job over and over, and don't necessarily specialize in diagnostic type work. (This is not to say they are not great guys...they've sure helped me alot)

But they may not have tested your service through (downstream of the) your meter, and not tested it under load conditions. Sometimes they just take a MM and see 120 to neutral and 240 accross hot and assume everything is fine.

I like Bob's idea above, and I think POCO will do it for you, especially if you show them the dimming of your light at before the service entrance...

Just another set of thoughts to consider.

Best

Peter
 
#30 ·
martingale2012 said:
Hi Dan
I checked the transformer last night and cant find any letters on it to identify if it's 10KW or bigger.
I will post a picture tomorrow. is there anything else I can check to know it's spec?
First, does your transformer serve only your house? Is it rusted or black looking? Some older transformers can get pretty nasty. Hopefully no oil is dripping out, that would be a problem in itself.

POCO around here have a list of every transformer on the system with specifications. If you can't find a number on the unit, a quick call should help you identify. They do not need to show up at your house to give you this information. But like most companies, your POCO may do things differently.

Good luck.
 
#31 ·
Hi Dan

I took 2 pic of the transformer but cant see any identification on it.
a technician from peco came yesterday and said it's PERFECT normal and same stuff happen at his home.. I just cant believe how these people are thinking about it. I will call peco today and try to get a spec.

and there're 3 more house between me and transformer. i'm the last one in the line.

headache!
 

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#34 ·
martingale2012 said:
the distance from the meter to the transformer is about 300 ft.
is that too long?
Maybe, I've read in other forums that some POCO's limit their secondary drops to 250 ft. Also most state regulators place restrictions on voltage fluctuation say plus or minus 5% of normal.

I think you have reached a point where you need to bring in a professional with the proper testing and recording equipment.
 
#40 ·
Martingale.... Really...THANK YOU for the update... alot of people "forget"

Sounds like you're making headway, and my money is on Dans26 who had the same problem with a 10KW transformer.

And apparently, you are not crazy, and maybe/probably a better electrician than your POCO. (Oh my lights are supposed to flicker when I plug in my toaster:thumbup:)

Best

Peter
 
#41 ·
hoo. ya, i'm not crazy, :), i'm almost get used to it. but not my wife. :):)
she want a massage chair, which is a 3-4k investment with probably over 100 motors in it, the voltage/current spike when a/c kicks can damage the motor and ruin the chair and the enjoyment. so we wait to solve this thing. as for time being, we can only buy a $200 food massager at walmart. lol!
 
#45 ·
Martingale...... Shoot.....:censored::huh:

Couple questions:

Did they look over your meter pan closely.... for good contact, corrosion, especially the neutral.

Are you still getting the flicker on a light load... I think you were using your shopvac before.

Is that flicker still occuring in front (upstraem) of your main.

(Makes you wonder if the service connection bug might be poor.... I've never made, or watched closely, that splice.... no idea if you can F it up
I know you had your triplex replaced just recently, but wonder if it might be a very rare coincidence.... one time trying to jump my son's car, we had a bad jumper, so we swapped out a brand new one.... took us an hour before we figured out the brand new one was bad also:huh:
 
#46 ·
OP, how old is your house? You indicate it originally had a 100A panel, so either it's a tiny matchbox size house, or it's a "normal" sized house, just old.

My house, made in 1960, also has what appears to be a 100A panel. No main breaker, just a 50A "lights/plugs" and a 50A for the oven. A 30A dryer breaker and a double pole 20A for electric BB heater were added later on.

My lights also dim slightly when a window AC unit kicks on, I run the vacuum, microwave kicks on, etc. It's a function of how the house was initially wired up, the circuit map, not the amount of amps into the panel.

In other words, I could have a panel with 300 amps, but my lights on the kitchen circuit are still going to dim when the dryer kicks on due to the fact that circuit is maxed out.

Back in 1960 houses werent wired with consideration to playstations, laptop chargers, microwaves, multiple TVs, clock radios, computers, cable boxes, DVD players, etc. etc. being plugged in all over the house, LOL.
 
#47 ·
PECO technician came and upgraded the transformer from 10kw to 25kw.
but it still dims when a/c kicks off. they measured the voltage coming into the house and it's 240v, saying it's way above the regular voltage. what's the regular voltage anyway? 230?

it seems to be a real incurable disease now. wow
what else can we do. :wink::wink::wink:
 
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