Is there a way to test if breakers are getting over loaded?

[1Garageman]

I know the basics about electricity and that's it. I have spots in my house, like the garage, where several sockets and lights are all plugged into the 1st breaker. When every my air compressor, which is also on that breaker, kicks on the lites blink and I think dim a little. I was wondering if I could check and see if I have to many "amps" running on that breaker or something? It's a 20amp breaker that it is running on, and yes the ligthts are on the same breaker.
I have an old house that only has a 60amp breaker box for the whole house! I was just wanting to know if I could do some checking to make sure everything is running ok and not getting dangerous
Thanks!

 

[Mike83]

The way to test if breakers are overloaded is see if they trip! Startup amps are always high for stuff like compressors, so they pull a little more power from the circuit causing the dim lights, but if a dangerous amount of current is drawn the breaker will trip.

 

[benjamming]

Does the breaker trip? Unless of course the breakers are fradulent/mislabeled, etc.
What size is the wiring?

 

[pattenp]

If you have access to an ampmeter you can check the running load on that circuit at the panel box with the compressor and lights turned on. The load should not exceed 16 amps which is 80% of the rated 20 amp breaker. If you're not exceeding the 16 amps and the compressor is not tripping the breaker at start-up you should be ok. But this all depends on what else you plug into those sockets and run at the same time.

 

[Falcon67]

This is kinda typical for 110V I think. The motor kick-on will create a momentary dip in the current and cause the lights to blink. My little 1 1/2 HP compressor used to make every light in the shop chatter and not all the lights were on the same circuit, just on the same side of the 220V shop feed. The new 3 HP 220V unit used both sides of the line so there is less load on each leg. No chatter.

The best way to tell how much load is on a feed is to open the box and put a clamp-on ammeter on the line from the breaker. As said above, make sure the breaker is sized to the line. 20A breaker on a loaded 14 gauge line is asking for flames.

 

[sberry]

For intermittent loads you can run 20A on a 20A circuit. When you wire it dedicated or continuous then you should follow the 16 a guide.

 

[beartoothweb]

I have a 200A main panel and when my AC compressor (220V) kicks in, I get a very quick incoming voltage drop and slight flicker/dim of the lights. I figured it's normal.

 

[sparky1562]

Most of this has already been said:
1. If the breaker doesn't trip, you probably don't have a problem.
2. add up the watts of the lamps installed and divide by 120, look at the nameplate of any thing that is always plugged in for amps, add that, add in the run load amps of the compressor and if it's under 16 you are okay. A 20 amp breaker is an 80% device and is designed to hold 16 amps indefinetly. over 16 and it will trip given enough time.
3. Make sure the wire coming off the breaker is #12.
4. Voltage drop on the circuit when the compressor is starting causes the lights to dim. If it's excessive, the breaker could trip, the compressor could kick out on overload, and electronics plugged into the circuit might not like it. Excessive voltage drop on start up could eventually damage the compressor. If it starts fine every time, you should be okay.
5. Like was said, less voltage drop if were 240 on the same size wire as it is at 120. How long is the circuit from the breaker to the compressor? shorter run, bigger wire, less impedance, less voltage drop. Your limited by the 60 amp feeder to some extent.

 

[Chris Adams]

One nice gadget is a 'kill-a-watt' you can buy online, or cheap at Harbor Freight.

You plug it into the wall, plug your appliance, TV, whatever, into it and then you can see how much current the device is actually using.

Test for anything on a breaker, write down the amounts and you can tell if you are heading into danger.

It doesn't do 220 though.

Your 220 device won't be sharing with anything, so you can just use the numbers on the device and verify the breaker is adequate.