Troubleshooting Advice. AFCI breaker keeps tripping.

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Old 03-22-16, 09:59 PM
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Troubleshooting Advice. AFCI breaker keeps tripping.

Hello all, new here! I have an electronics background from the Naval Avionics, and for the last 10 years have worked as a field service engineer in medical device. When it comes to homes, I get very paranoid messing or trying to look at electrical.

This home was built right around 2002-2003 I believe, and there are two 15A afci breakers, with two bedrooms running on each. For about 2 years every once in awhile the same breaker for our guest bedroom and office would start tripping randomly. Not often at first, over the last year it started happening more and more, until one day it could not handle any load at all. No overhead fans, one room has two overhead lights, the other has one. I have pulled all of the bulbs, and nothing is plugged into any receptacle.

Tonight I started to get into it. Swapped the two breakers with each other, the other breaker would trip on this circuit, so I'm eliminating the possibility of the breaker. Voltage is fine at every outlet. I plugged a receptacle/GFCI tester in every outlet tonight, and they checked good. Until I got to the very first outlet in the guest bedroom, and as soon as I plugged the tester in, the breaker tripped. Now this didn't happen with every other outlet I tested. I then reset the breaker, and plugged it in again. This time it didn't trip, but now everytime I press the GFCI tester button, it trips. So pretty much, one outlet out of the two bedrooms, will cause the AFCI breaker to trip, when the GFCI button on the tester is pressed. I pulled the outlet out, every outlet in this house seems to be backstabbed. Also, I'm almost positive this is the first outlet in series with the breaker, and if I take the hot lines off, then no other outlet gets power They all seem to be wired in series. I then wired both hots, with their respective neutrals and bypassed the outlet. Turn on the breaker, and it trips right away when the outlet is bypassed. If i leave both hots and neutrals disconnect from everything, the breaker doesn't trip and I get voltage on the incoming hot wire. Also when I put my meter on ohms and measure from the incoming hot wire to ground, it kind of flucuates between open and Megaohms. The hot wire should always read open to ground right? I guess I'm trying to figure out what to do from here!??
 
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Old 03-22-16, 10:59 PM
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Some measurements that may help the Pros help you.Best to use an analog multimeter but a digital will do.
  • (Breaker off) what is the resistance neutral to ground?
  • What is the voltage from hot to ground?
  • What is the voltage from neutral to ground?
  • What is the voltage from neutral to ground?
 

Last edited by ray2047; 03-23-16 at 12:13 AM.
  #3  
Old 03-23-16, 05:47 AM
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what reading did you get on the other wires feeding to the next outlet (other set of wires at the first receptacle)?using you Ohm meter
 
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Old 03-23-16, 08:06 AM
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My first thought is when you said the outlets are back stabbed is that one of the outlets has a loose connection. If it was me I'd pull every outlet on the circuit and redo the connections using the screws with pigtails.
 
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Old 03-23-16, 07:33 PM
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Okay so now i'm just as confused as ever. First off I am an idiot and when I thought I was bypassing the receptacle, all I did was wire the hot straight to neutral with no load, so that's why the breaker tripped right away. So tonight I bypassed the outlet and wired the hot to the rest of the circuit and it didn't trip right away. But as soon as I plugged in a load, the breaker tripped. So I don't see anything wrong with that receptacle.

Here are the readings I am getting from the outlet I have been looking at. Hot to ground.....774 M Ohms. Hot to Neutral 777 M Ohms. Neutral to Ground has continuity - 0 ohms.

Like before, the outlet tester reads good on every outlet. When I plus it into the outlet I have been testing, it reads good. Then when I hit the GFCI button, it trips the AFCI 15A breaker. I'm confused on how this house is wired, because I thought this might have been the first outlet in series, because when I pulled the hot off, most of the outlets stopped working. Tonight I figured out that 2 or 3 other outlets and one overhead light still gets power to it when the line is off. ?? I'm just confused to all hell
 
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Old 03-23-16, 08:09 PM
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When I plus it into the outlet I have been testing, it reads good. Then when I hit the GFCI button, it trips the AFCI 15A breaker.
Many AFCI breakers also have a GFCI function so tripping the breaker would be the expected result. Refresh my memory have you tried a new AFCI breaker yet?
 
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Old 03-23-16, 08:31 PM
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Yeah I swapped the breaker with the other 15A afci, same result. These are very early siemens afci breakers, no led lights or anything. The gfci button on the tester didn't tripped when pressed on any other outlet on this circuit. Should the neutrals on the receptacles read continuity to ground?
 
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Old 03-24-16, 07:01 AM
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Should the neutrals on the receptacles read continuity to ground?
Yes. The neutral and ground are tied together in the main panel.

AFCI/GFCI combo breakers did not come out until just recently. (2014-ish)

Grounds touching a neutral screw on the receptacle is a common cause of an AFCI tripping. It is possible that a GFCI outlet tester could trip an AFCI because it does make a connection between hot and ground.
 
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