Stray voltage from AFCI breaker.

B

bigalbert

Member
Location
Stafford Springs, Connecticut
Occupation
Electrician
I was troubleshooting a single switched outlet in a living room. The circuit is controlled by a 15a AFCI breaker. With nothing plugged into the outlet and the three way switching is off I am seeing 52 vac from line to neutral and line to ground at the outlet. Both three way switches were replaced but it made no difference. When anything is plugged into the outlet even though the switch is off the 52 vac goes away. Is this just standard operating for an AFCI circuit ?
 
Is there a dimmer involved? There shouldn't be but I thought I would ask. Also is everything working properly except for the reading?
 
100% agree with Synchro above.

The thing that clinches it is that this voltage disappears when you plug anything into the outlet. Any kind of decent load will "drain" this induced voltage away, since it packs no real punch. You are likely measuring this all with a high impedance meter, which is designed to add very little load to what it's measuring, so it has very little effect on the circuit and won't pull down this phantom voltage.

But a normal bulb plugged into the socket would. Which is why Synchro was asking if you had a low impedance meter to measure with.

Just curious - what was the original problem you were troubleshooting?
 
Dennis Alwon said:
Is there a dimmer involved? There shouldn't be but I thought I would ask. Also is everything working properly except for the reading?
Click to expand...
Hello. No, there is no dimmer. There are no other outlets on the load of the switches. The 52 volts is only present when nothing is plugged into the outlet. With the switches off The voltage goes away as soon as anything is plugged in. There are no other problems in the house. It is the only AFCI breaker in the Murray panel.
 
MD Automation said:
100% agree with Synchro above.

The thing that clinches it is that this voltage disappears when you plug anything into the outlet. Any kind of decent load will "drain" this induced voltage away, since it packs no real punch. You are likely measuring this all with a high impedance meter, which is designed to add very little load to what it's measuring, so it has very little effect on the circuit and won't pull down this phantom voltage.

But a normal bulb plugged into the socket would. Which is why Synchro was asking if you had a low impedance meter to measure with.

Just curious - what was the original problem you were troubleshooting?
Click to expand...
Christmas tree lights went out. I had my meter with me so the first thing I checked was for voltage at the outlet. That’s when I saw the 52 volts. Of course at the end of it all it was a blown fuse in the string of lights.
 
MD Automation said:
100% agree with Synchro above.

The thing that clinches it is that this voltage disappears when you plug anything into the outlet. Any kind of decent load will "drain" this induced voltage away, since it packs no real punch. You are likely measuring this all with a high impedance meter, which is designed to add very little load to what it's measuring, so it has very little effect on the circuit and won't pull down this phantom voltage.

But a normal bulb plugged into the socket would. Which is why Synchro was asking if you had a low impedance meter to measure with.

Just curious - what was the original problem you were troubleshooting?
Click to expand...
Christmas tree lights went out. It turned to be a blown fuse in the cord for the lights.
 
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