ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Grounding electrodes
by gfretwell - 09/07/21 03:41 PM
Looking For Electricians in the Midlands
by Alex247 - 09/06/21 05:26 AM
Backup Generator Done Right
by timmp - 08/31/21 04:44 PM
New in the Gallery:
Now you know.
Now you know.
by Tom_Horne, September 7
February, North East Indiana
February, North East Indiana
by timmp, July 25
Who's Online Now
0 members (), 34 guests, and 17 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
#188858 09/07/09 08:37 PM
Joined: Mar 2005
Posts: 236
Member
I have a AFI that keeps tripping when I turn the lights on, when I take all the bulbs out the circuit holds...ok bad AFI right? Wrong, for kicks and giggles I removed the neutral from the AFI and landed in the busbar and tested the lights again, and again they tripped the breaker. Anybody seen this b-4? It seems if the switch leg was crissed cross to the neut, then the circuit would trip regardless if the lamp was present. What are some other reasons you guys can think of?

2017 / 2014 NEC & Related Books and Study Guides
Joined: Mar 2004
Posts: 947
T
twh Offline
Member
Neutrals from two circuits tied together or a neutral faulted to ground. Arc fault breakers also trip on a ground fault.

twh #188867 09/08/09 01:55 AM
Joined: Mar 2005
Posts: 236
Member
I agree with you twh. But I took the neut out of series with the AFI(standard breaker now. I should be more specific that with the light bulbs out, I can turn switch on and read 120V on the switch leg side of the switch. Put in lamp and turn same switch and breaker trips.

Joined: Jul 2002
Posts: 8,407
Likes: 2
Member
Have you tried a different lamp in the fitting, the filament may be about to break.

Trumpy #188876 09/08/09 11:20 AM
Joined: Oct 2002
Posts: 482
Z
Member
Shared Neutral downstream? AFCIs do not like shared neutrals, anywhere in the circuit. The fact that the AFCI trips when the lights go on, but not before, may further indicate the shared neutral possibility. Directly landing the neutral in the panel would have no affect on this issue. The neutral would still be shared within the branch circuit(s).

Good Luck!

Zapped #188952 09/12/09 11:27 PM
Joined: Nov 2007
Posts: 763
K
Member
Iíve seen that exact same thing happen twice before. Both were because of damaged NM cables in the walls on new construction. The neutral and grounding conductor where mashed together in the wall. Luckily these were not on my own jobs, but I still had the unfortunate task of locating the problems for someone else.

Sometimes the grounding conductor and neutral are touching somewhere downstream in one of the receptacle outlets. It could cause AFCI tripping when a load is applied, meaning something is plugged in or a light on the circuit is turned on.

twh #189526 10/14/09 01:38 PM
Joined: Mar 2005
Posts: 1,213
S
Member
Originally Posted by twh
Neutrals from two circuits tied together or a neutral faulted to ground. Arc fault breakers also trip on a ground fault.
Removing the neutral from the AFI and landing it directly to the bus bar will trip out the unit on ground fault if any current at all passes through the hot conductor, just like if you'd done it to a GFCI. This method can't be used to troubleshoot.

If the AFCI only trips when the light switch is turned on, even if there are no bulbs in it, I suspect a wiring fault with the hot conductor, either a crossed neutral connection or a short circuit somewhere. Nail through NM will do this. At least you can narrow it down to that lighting string!

Either way, it's been a month, did you ever find the cause?


Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Trumpy
Trumpy
SI,New Zealand
Posts: 8,407
Joined: July 2002
Top Posters(30 Days)
timmp 3
Popular Topics(Views)
282,908 Are you busy
216,673 Re: Forum
203,099 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5