Lights dim

[dragonballz]

Lights dim when appliance/powertool first turns on

Just bought the house in Massachusetts. Built in 1960. It’s the last house on a dead end street. My neighbors' houses dont have this problem.

The lights dim by a large amount during initial startup of an appliance with high draw. Vacuum, wallpaper steamer, dehumidifer, bandsaw, etc. I've seen lights dim a tiny amount in other houses but mine dim by such a large amount that I get startled, like WTF!

200 amp service. All 15 amp breakers. Old romex.

Here is a scenario:

Room 1 is on circuit 1. Room 2 is on circuit 2. The lights in room 1 dim initially when the vacuum is plugged in to circuit 1 and turned on. The lights in room 2 do NOT dim when the vacuum is plugged into circuit 1. The lights in room 2 dim initially when the vacuum is plugged in to circuit 2 and turned on. This happens for all rooms.

Thanks for any tips for diagnosing.

 

[mark#3]

I'd check for loose connections,

 

[Bigblockyeti]

Check to see what gauge wire is run from the panel. Then with a meter in the same receptacle as the vacuum, see what you voltage is before turning it on and the lowest it drops to as the vac is spooling up. Dropping below 100V would be undesirable. Check all wire connections to ensure they're tight then repeat the test to see if results change.

 

[JohnKal]

Check your grounds

 

[ard]

Hmm. Kind of odd that two circuits have the same behavior... BUT...they don’t ‘cross over’, (is room one doesn’t dim room 2 and vice versa.)

And ALL circuits do this? Not just two?

You could have a handful of bad connections, maybe backstabs, all of which are failing at the same time. But this would be unlilkely.

Is there a SINGLE point of failure that would cause this?? Check out the main panel, look at the bar where all neutrals are attached. Check for loose screws. Did someone stuff wires in and fail to tighten?

Report back

 

[MFolks]

Kill the main breaker,open up the wall receptacles, looking for back stabbed wires,take them out and use the screw connections, or replace if worn.

 

[dragonballz]

Hmm. Kind of odd that two circuits have the same behavior... BUT...they don’t ‘cross over’, (is room one doesn’t dim room 2 and vice versa.)

And ALL circuits do this? Not just two?

You could have a handful of bad connections, maybe backstabs, all of which are failing at the same time. But this would be unlilkely.

Is there a SINGLE point of failure that would cause this?? Check out the main panel, look at the bar where all neutrals are attached. Check for loose screws. Did someone stuff wires in and fail to tighten?

Report back

It is at least 5 rooms because I've used power equipment in those rooms. I will double check the "cross over" because I havent been in 2 rooms at the same time lol. But the reason I said there is no "cross over" is because one of the rooms have the lights and receptacles on 2 separate circuits and the lights did not dim. I will do more diagnosing and experimenting when I get back to the house.

I dont know if the 200 amp panel is original to the house. But I don't know when it was added.

Thanks

 

[engineer2]

I'd be looking for loose connections everywhere including at the breaker panel.
" Built in 1960. " Are you sure it's all copper wire? I recall in the early 60's aluminum wiring was the "next big thing" until they found thermal cycling and corrosion caused poor connections.

 

[dragonballz]

Kill the main breaker,open up the wall receptacles, looking for back stabbed wires,take them out and use the screw connections, or replace if worn.

Are "back stabbed" connections the one where a straight conductor goes straight into the terminal and then clamped with a screw?

You're saying take them out and wrap the conductor around the screw head and tighten?

 

[dragonballz]

I'd be looking for loose connections everywhere including at the breaker panel.
" Built in 1960. " Are you sure it's all copper wire? I recall in the early 60's aluminum wiring was the "next big thing" until they found thermal cycling and corrosion caused poor connections.

I am not sure. I will check when I get back to the house. I'm unsure if the 200 amp panel is original to the house.

 

[whtbaron]

Not sure how your house is hooked to the incoming line, but I have buildings where the mast goes up and attaches to an incoming triplex cable. The attaching clamps have been known to loosen in the wind or corrode over time (the ones I replaced were installed in the 70's so newer than yours). If one connection is bad its' lowering half the voltage coming into your house and would be common to all circuits.

 

[dragonballz]

Not sure how your house is hooked to the incoming line, but I have buildings where the mast goes up and attaches to an incoming triplex cable. The attaching clamps have been known to loosen in the wind or corrode over time (the ones I replaced were installed in the 70's so newer than yours). If one connection is bad its' lowering half the voltage coming into your house and would be common to all circuits.

If this was the case, wouldn't the whole house dim regardless of what circuit the appliance is plugged into?

I know you're in Canada so maybe somebody else could answer this. Would the triplex clamps be my responsibility or the electric company's?

 

[rlitman]

Check your grounds

Grounds aren't (or at least shouldn't be) current carrying, so they have no bearing on voltage drop.

Are "back stabbed" connections the one where a straight conductor goes straight into the terminal and then clamped with a screw?

You're saying take them out and wrap the conductor around the screw head and tighten?

NO. If the wires are clamped by a screw, they are fine. In fact, that is probably better than wrapped under the screw head.

The bad type of "back stabbed" connectors are pushed in and locked in place by a spring.

 

[SGKent]

first thing you do always is call the Power Company and have them test the power at their side of the panel. It may be corrosion in the lines from the street, or a squirrel has chewed part of a line thru. Happens all the time. I've been in at least 3 or 4 homes in my life where the problem was outside, not inside. You could have only one side of the pair bad and that is servicing the rooms you are seeing the issue in.

 

[ard]

If this was the case, wouldn't the whole house dim regardless of what circuit the appliance is plugged into?

Yes, hence my question about 'crossover'.

It isnt impossible that you have the same issues on multiple circuits. But it is more likely a single point of failure. So what single 'thing' can generate the issues you see.

Better to use a meter, and track voltages. Write it down too. If you ever need to deal with the poco having notes and details will help convince them you arent the typical clueless homeowner with a 'inside the house wiring issue'. But again, we arent there yet. You dont call the poco until the voltages on your main breaker are dipping with load....

 

[dragonballz]

first thing you do always is call the Power Company and have them test the power at their side of the panel. It may be corrosion in the lines from the street, or a squirrel has chewed part of a line thru. Happens all the time. I've been in at least 3 or 4 homes in my life where the problem was outside, not inside. You could have only one side of the pair bad and that is servicing the rooms you are seeing the issue in.

I think i would want to eliminate any possible factors in my house before calling the electric company. Wont I have to pay them?

 

[MFolks]

"Back stabbing" is the quick and dirty way of wiring,over time(years?), the connections loosens,if the receptacle looks worn(plugs won't stay in tight),now's the time to replace them. I never use backstabbing, preferring to wrap the wires around the screws on the receptacles.

 

[Bert_]

I think i would want to eliminate any possible factors in my house before calling the electric company. Wont I have to pay them?

They will check their side of the meter without any cost to you.

 

[dragonballz]

They will check their side of the meter without any cost to you.

Should I call and say, “My lights dim when it’s windy out. My neighbors dont have that problem. An electrician told me to call you.”

 

[cybrdyke]

Should I call and say, “My lights dim when it’s windy out. My neighbors dont have that problem. An electrician told me to call you.”

Yes. You wont be the first one to call them. Nor the last.
CD

 

[Miss the Pontiacs]

Outside of your home would be a good place to start. Since you are the last house on the service line and I am guessing aerial feed and not buried. That the line is running through some tree limbs and not coming in at 90 degrees from the feeder line but angling in and having more trees in its path. If the power is arcing into some of these limbs it would cause havoc to your power in the house.
You may have one side 120v of your 240v fed going open in the wind. You might have a loose connector where the service wire is tied into the feed to your panel. Again affecting only one side of your power.
On my panel it is odd breakers on one side of the 120v and even on the other. You could check this with a volt meter but might not show up if not windy etc.
I would think it is up to your service provider to do the initial trouble shooting. I know it would be for me.
The problems you are experiencing aren’t the best for your appliances either.
Good luck

 

[nadogail]

I had that once in a brand new house, the city building inspector fixed it by tightening the conections.

 

[dragonballz]

UPDATE:

I measured 122v at the outlets. A good, non-dimming circuit is 121-122v during appliance start up. A dimming circuit read 113v during appliance start up. I only measured 1 circuit. And this wasnt even the worst one. I’m sure it would read lower if i had an oscilliscope or an analog meter. Should have measured the other circuits. I have at least 4 dimming circuits.

There is a newer, short ran circuit for a light bulb, switch, and outlet from the electrical panel at the electrical panel. That bulb dimmed very slightly when i plugged an appliance into that outlet. We tighted all the neutrals in the panel. This bulb no longer dimmed! The other lights still dimmed on their respective circuits.

I opened all the receptecles and switches and tighted all connections. They still dimmed the same.

I think I’m just going to run all new romex and replace all receptacles and switches.

Also going to call the electric conpany because we had a windy day today. I saw 1 flicker

Thanks everybody

 

[Bert_]

I would not spend any time replacing Romex. That is almost certainly not the issue

 

[dragonballz]

I would not spend any time replacing Romex. That is almost certainly not the issue

I'm honestly stumped. Would a single bad connection on any component on a circuit cause a voltage drop everywhere in the circuit during high current draw of an appliance start up?

 

[Bert_]

Have you measured voltage at the panel with a large load running/starting?

Is the appliance you are using to test connected to the same circuit you are testing? Depending the appliance a small amount of dimming is NORMAL when the appliance starts.

Wire does not go bad. It's the connections that cause issues. If the circuit is extremely long as can happen in large buildings larger wire is sometimes needed to keep voltage drop manageable. This is not normally needed in a house.

 

[dragonballz]

Have you measured voltage at the panel with a large load running/starting?

Is the appliance you are using to test connected to the same circuit you are testing? Depending the appliance a small amount of dimming is NORMAL when the appliance starts.

Wire does not go bad. It's the connections that cause issues. If the circuit is extremely long as can happen in large buildings larger wire is sometimes needed to keep voltage drop manageable. This is not normally needed in a house.

I did not, I will measure at the panel tomorrow.

Yes, the circuit that I plug the appliance into is the one that dims. The dimming does not cross over to other circuits, unless I plug into that respective circuit. Not all circuits have the dimming. One of the circuits is so bad that it appears that the lights shut off completely for a split second, I did not measure that circuit. I will do it tomorrow. The other bad circuit that I measured dropped to 113v under load from 122v resting. My good circuits don't dim at all, not even a little bit.

I'm aware that connections can cause issues. I've tightened all neutrals at the panel. Only 1 circuit's dimming was fixed and that was a newer circuit that was installed when the 200 amp panel was installed. I tightened all connections at the receptacles and switches. All of the bad circuits are still dimming the same.

I will double check other connections at the panel. I will call the electric company for them to check their connections outside, but if that was the problem, wouldn't all my lights dim?

I've found about 15 dead mice during my demolition. I've caught 6 new mice in mouse traps within 2 months. Could they have been chewing on the wires?

I'm using a shopvac as the load

 

[dragonballz]

I measured at the panel. There is no voltage drop at the main and no drop at the circuit breaker of the dimming circuit. I checked for tightness. One of the big cable’s clamp bolt was slightly loose. Tightned it but did not fix any dimming. There is still a voltage drop at the dimming receptacles

 

[Bert_]

How long are the circuits?

 

[dragonballz]

How long are the circuits?

The house is a small garrison colonial. Footprint is 20’ x 30’. I don’t think they can be too long.

I opened some recepicle boxes and light boxes. I found out that some neutrals are twisted together and soldered. Did not find the culprit but thats could be another point of failure

 

[Bogie1632]

No voltage drop at the panel is good. Did I miss you stating what gauge wiring you have on the affected circuits? I'd check the panel side gauge and at the outlets and switches. Voltage drop could simply be from bad connections (loose or carbon build up from arcing, don't trust all wire nut connections to be good), too many demands on the circuit (gauge and number can affect this progressively the farther down the line you go) and even changes on gauge along the circuit (more connections). And undue any back stabbed connections you find. Those tend to only get worse over time. Mapping out and listing anything as you go may help narrow your culprit down further.

Good luck.

V/R
Bogie

 

[SGKent]

flip the breaker off and determine which circuits in the house are on that circuit. Plug a hair dryer into the receptacle closest to the service box and have someone hold it because lying it down could start a fire. With it running measure the voltage at the receptacle. Now go measure it at the panel. If there is much of a difference a problem exists between that receptacle and the panel. Turn the breaker off, pull the receptacle, turn the breaker back on, and measure the voltage where it goes into the receptacle. There should be no boxes between that receptacle and the panel. You may have to go in the attic or basement to follow the wire looking for damage. If the first receptacle is Ok move to the next one and repeat. Turn the breaker back off while you are working on each receptacle to remove and put it back into the box. I had a similar problem when I bought this house when the timer on the microwave would reset sometimes. I was going out the garage and shut the side door, and heard it beep. The neutral was poorly attached to the wire nut in the box by the door when the PO replaced the receptacle. Everything down the line had a goofy neutral because of it. Fixing that solved the issue.

That said, if the lights flicker when the wind blows it sure sounds like you have a problem with the lines coming in. Since the power comes in on 2 sides, each carrying 120V above neutral, it is possible for only some circuits wired to that side to be affected and not the others on the opposite leg.

 

[arsco]

I would look for a bad neutral on the service side. Neutral to ground rod should be zero volts with wire lifted

 

[Milton Shaw]

Arsco has it right, loose neutral. I had the same problem with voltage dropout causing my UPS computer power supplies to trip out. Power company came out, pulled meter and measured each leg to neutral and to ground and found a loose or floating neutral. They went to the pole and transformer found and fixed the problem. No problem in the last 3 years or so since they did it. Each leg would change voltage to neutral when load applied.

 

[TractorJeff]

If the meter the OP is using does NOT have a Min/Max function, then 113 from 122 is all he will ever see. Hence why he mentioned needing a Analog Meter

 

[wyliesdiesels]

Check your grounds

awww no. grounds have absolutely nothing to do with this

Are "back stabbed" connections the one where a straight conductor goes straight into the terminal and then clamped with a screw?

You're saying take them out and wrap the conductor around the screw head and tighten?

no theyre clamped with a spring like tensioner

Not sure how your house is hooked to the incoming line, but I have buildings where the mast goes up and attaches to an incoming triplex cable. The attaching clamps have been known to loosen in the wind or corrode over time (the ones I replaced were installed in the 70's so newer than yours). If one connection is bad its' lowering half the voltage coming into your house and would be common to all circuits.

no it would only affect the circuits which are on that leg.

 

[engineer2]

My parents had a neutral connection come loose off the pole in the back. Strange things would happen with appliances in the house.
Dad called the power company and explained it to them in great detail using engineering terms to describe what was happening in the house. They never came out figuring it was not their problem.
I told him to call and simply say "there is a loose wire dangling off the pole". Thay had it fixed in 2 hours.

 

[dragonballz]

Power company came today. He replaced 3 connections outside the house and on the pole. Still dims. The guy said they will come back to replace an old cable (on the pole?) and do something to the transformer (replace?). I am the last house on the street.

 

[wyliesdiesels]

Since theres no voltage drop at the main panel, its not an issue on the PoCo company’s side.

 

[bullnerd]

Im not an electrician so....

What the condition of the panel and meter pan?

Do they look like they have ever had water intrusion?

Pics of each?