Why lights in house dim when appliances kick in?

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Posted by: from King City
1/2/2015 at 1:02:15 AM

Even though I have my dryer and fridge and ac on their own circuits I still notice that all the lights in my house will dim.

I've had an electrican check for any loose connections but said everything is tight. I have a 100 amp breaker. I had hydro one come out and check the line and they said I have the old 60 amp meter still on the outside of the house.

They said if I upgraded the outside meter they would increase the power line from the pole to my house. Does this sound like the fix?

Also who is responsible for the outside meter change? The hydro company tech said I would be, but that doesn't sound right.


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Robert from Electrilight Ltd. in Oakville
Date/Time1/2/2015 at 8:04:19 AM

Lights generally dim in homes due to voltage drop or draw. The real technical theory is far too deep for this board and by the time it was covered, you'd be sleeping, but essentially there are many things would could be covered to try and fix this, but first the easy answer; the meter base and anything attached to your home is your responsibility, if you want underground to the pole that is also your cost, so hydro one is correct.

As far as the lights dimming most common reasons: old wires, faulty connections, wires too long, too many devices on circuit causing too much resistance, old appliances that have high resistance start-up, aluminum wiring.

The idea upgrading your home from 60 to 100 amps could help and sort the problem, which I have seen as most meter bases of that age are old and connections failing. It is certainly the best place to start and over-all the safest for your home so consider it. A stove draws 40 amps, a dryer draws 30 amps, so if both of these are drawing capacity of 30 + 20 respectively, there is your 60 amp main feed.

If you have a 60 amp incoming line, and you have a 100 amp main breaker, someone did an illegal upgrade without a permit. Get it repaired or at least checked over as the incoming insulation on the lines could start melting before the main breaker does its job.

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Date/Time1/2/2015 at 10:50:47 AM

Hi Steve

It sounds like you have done the right things; from this point the obvious things are a loose connection down stream, low or fluctuating voltage from the transformer or an imbalanced load on one of the two phases (lines) coming into your home.

As Rob stated, all the equipment for the service except for the actual meter and the wire from the pole, is your responsibility. However you said the hydro stated it was a "60 amp meter". I am pretty sure all meters are rated at 200 amps, so that does not sound like an issue. Even if there were 60 amp meters, I would have suspected that yours has been changed in the last 10 years, as most meters (gas, water and hydro) have about a 10 year maintenance cycle and are often replaced.

If you are talking about the size of the service (60, 100, 200, etc), the actual size of the service has really nothing to do with the diming except that you may have voltage drop in the line coming into your house because you are drawing considerably more then 60 amps which is an issue all on its own. As Rob also said, if you have a 100 amp service breaker and a 60 amp service, you have had some illegal work completed. I recently just looked at a similar situation in Hamilton so it is possible.

I think by upgrading your service, the hydro is saying that they will increase the size of the feeder line to your home or have completed a load test and determined that you are drawing more then 60 amps. To be perfectly honest, unless your house is pretty big or everything you have is electric such as stove, dryer, heat, hot water tank, etc I would say that you normally would not draw 60 amps. However if you have any of these that are electric, you should be looking at a 100 amp service minimum and would consider a 200 amp service since it is not that much more in cost.



John Kuehnl-Cadwell

Master Electrician

Datawise Solutions Inc

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Dave from 360renos in Navan
Date/Time1/3/2015 at 12:15:04 PM

Hi Rob and John,

You guys are awesome for helping home owners out with their electrical questions.

True Pros!!

Can I entice you to move to Ottawa?!!!

Happy New Year!


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Steve in King City
Date/Time1/3/2015 at 1:02:00 PM

Thanks to everyone that has responded.

OK, lets start with the meter. It is just a round meter outside (I assume the smart meter in Ontario?...was replaced about 6-7 years ago?). Does this mean it could still be the old 60amp rating since Hydro one still thinks that my house (a 50 year old bungalow) still has the old 60 amp panel inside? I believe the previous owners upgrade to a newer 100amp panel, but I'm not sure of the details.

When I had the electrician come to my house he said that he checked if wires were tight, but I'm not sure if he did a thorough job. Also, I'm not sure if he checked line voltages to see if they were balanced or not, or if the grounds look good (it its wrapped around the water pipe that comes into my house).

When the hydro guys came they said they noticed a bit of a problem where the line attached to my roof pole but I assumed they fixed that. He did say if I had an electrician come out and upgrade the outside meter they would add a larger drop line.

I'm not sure what another electrician will charge to come out and try to resolve this problem. Is it going to be a chasing game where the electrician will want to blame hydro one or hydro one saying the problem is inside? Will an electrician be able to definitively find a problem here?

I'm trying to be most efficient with where I start (money wise). I only have 1 electric dryer and a gas only major consumers of electricity other than that, so I can't say that I'm over drawing power here.

Thanks again.

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Date/Time1/4/2015 at 3:08:00 AM

Thanks for that Dave, it is appreciated.

Steve, I am not aware of any smart meters that are not rated for 200 amps, so as I suspected you likely are talking about your service rating and not specifically your meter.

Trying not to get to technical, but it is possible to have a 100 amp panel on a 60 amp service. The main breaker has to be sized properly. So if the main breaker is 60 amps, then you are OK to have a 100 amp panel. If your main breaker is 100 amps, then you like have a non-compliant installation that potentially could be a safety issue.

So back to the basics... loose connection is the most common cause for this issue. An electrician should check all the connections in the panel (and sub panels), all the breakers and the ground / bonds. An electrician should also do a voltage test and a current test to see if the supply is within acceptable range. These tests should be done over a 24 hour period to see if it is specific to a time of day (high usage in the evening as an example) or specific to a particular use of appliance or demand.

Armed with this information, you can determine if the problem is interior or exterior to your home. If the situation continues then it is time to bring in the local utility who should renew the connections at the pole / transformer, renew the connections inside the meterbase, clean the lugs for the meter jaw assembly and check their own connections at the pole or transformer. Once that is done, they usually put in a load meter that puts a load on the system and sees if their supply is sufficient. The results of that test determine the next steps.

So it sounds like you have had both an electrician and the local utility out there... so that should have fixed or isolated the problem.

More to follow...

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Date/Time1/4/2015 at 3:08:17 AM

Next Steps:

If in fact you do have a 60 amp service and a 100 amp main breaker and panel, you need to get that fixed ASAP (regardless of anything else). If your problem is that you are drawing more than 60 amps (thus creating a voltage drop), this will solve your problem. If it is not the problem, you still have a potentially dangerous situation that needs to be corrected.

If you have a 60 amp service with a 60 amp breaker, you might be at or near capacity thus creating a similar situation as voltage drop.

Mkae sure all the connections are tight and the Ground / bonds are renewed. If your tests show that you have an imbalance, then your electrician should adjust the loads in the panel to compensate for that.

If your tests show a low voltage and an acceptable range of current, then it is a hydro problem. They need to change the taps on the transformer to provide a higher voltage or install a larger transformer.



John Kuehnl-Cadwell

Master Electrician

Datawise Solutions Inc

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Steve in King City
Date/Time1/8/2015 at 2:41:07 PM

I had Hydro One (hydro company) come back to my house today to take another look at the outside wiring. The main power line from the street post to my house mast runs through a set of tall pine trees. They said that the power line was in really bad condition and they will need to re-run a new line.

Clearly, this is an obvious issue and I'm hoping is the cause of the dimming. I'll update this forum once the line is replaced and I've had a chance to test things out.

This seems like it could be the fix.

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Date/Time1/8/2015 at 8:41:33 PM

I look forward to hearing the results.



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Steve in King City
Date/Time1/12/2015 at 11:37:24 AM

Success! Hydro One came out on Sunday (of all days) and replaced the line from the street post to my house mast. Said they noticed some burning on the line. Once the new line was in place I tested everything out. I turned on my coffee machine, the wife's hair iron, microwave, dryer all at the same time.

Problem gone! Cannot notice any more dimming of the lights.

Thanks to all that helped out.

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