AC300 tripping Arc Fault (AFCI) breaker

Have AC300 connected to 10 circuit manual transfer switch and 9 of the breakers are working with no problem but the only one that is a 15 amp Arc Fault (AFCI) breaker trips immediately when I switch over to the AC300. Have had electricians over to replace breaker but new one does the same and they did a complete check of the circuit and tried it with a regular breaker and it works fine. Put the Arc Fault breaker back and keeps tripping. By law, I must have the Arc Fault breaker for all bedrooms so I can’t change it.

Anyone else have this problem?

Yes, my ARC breakers often trip when switching the transfer switch. This is actually pretty common with a standard transfer switch… they make specialized ones for ARC and GFCI breakers.

Also be sure to check out this thread.

Thanks for the reply and I’ll check the other thread.

Disclaimer, I am not a licensed electrician.

What I suspect is that the AFCI in your panel is tripping because when supplied by the manual transfer switch (is it like a reliance TransPro?) the current supply only is supplied by the breaker there, and the return goes through the existing AFCI causing a current imbalance in the AFCI breaker. I believe some(all?) AFCI’s trip under this condition. perhaps an electrician or engineer could chime in…

BTW… If i’m correct this same thing would occur if an AFCI was put into the transfer switch to supply the circuit. in either case supply is from the breaker in he transfer switch, and return goes the existing AFCI in your panel


Thank you for responding!

I have had discussions this morning with Reliance Controls, the maker of the older ProTran and newer ProTran2 manual transfer switches. I have the older ProTran transfer switch.

They told me that the 15 amp AFCI breaker in my main breaker panel will always trip when switching from the grid to the backup battery but that is ok because the power from the battery is running that circuit and is protected by the 15 amp breaker in the manual transfer switch. I verified that the circuit is live under the battery backup even though the AFCI breaker in my main circuit breaker is tripped.

If I want the circuit protected by a 15 amp AFCI breaker while the circuit is running on backup power, simply change the 15 amp circuit breaker in the manual transfer switch to a 15 amp AFCI breaker.

This can be done only with the newer ProTran2 manual transfer switch since it has replaceable breakers. The older ProTran manual transfer switch has circuit breakers that cannot be changed.

I had an electrician install the manual transfer switch and when the AFCI breaker tripped, he said that the circuit was down and obviously he didn’t check. At that point he switched back to the grid and said that my AC300 was causing the AFCI to trip. He obviously has never worked on a manual transfer switch before and didn’t understand how it worked.

I thank you for your interest and hopefully this can help other AC300 owners.


Hi Leonp,

That’s very interesting. I thought most AFCI’s disconnect both the hot and neutral. In which case the circuit would be “energized” from your transfer switch breaker, but not have a neutral return through the AFCI in the main panel to actually have current through a load.

It would be useful to know what brand AFCI you are using in the main panel, because then a person would know a transfer switch like the protran would work with their AFCI’s in the main panel if they have that brand. But, it would still have to be nonAFCI when using the backup. If you put an AFCI breaker in the transfer switch it will not work, because there is no separate neutral for that circuit back to the protran.



Please see what I received from Reliance Controls about what is needed.

INSTRUCTIONS FOR INSTALLATION OF AFCI-GFCI CIRCUIT BREAKERS FOR RELIANCE CONTROLS LOADSIDE TM PRO/TRAN 2 TRANSFER SWITCHES WARNING: You will need:  One NK06 or NK10 NEUTRAL KIT. NK06 for the 6 circuit Transfer Panel or the NK10 for the 10 circuit Transfer Panel. NOTE: For use with 15 and 20 amp circuits only. An AFCI or GFCI circuit breaker should ONLY be installed into the transfer switch when connected to an AFCI or GFCI circuit breaker in the home loadcenter. Do not connect AFCI or GFCI protected circuits in the transfer switch to non-AFCI or non-GFCI breakers in the home loadcenter.

It continues on for about 4 pages of detailed instructions.

Customer Service at Reliance Controls really has their act together with quick replies to all of my questions.

Have a Great Day,

good to know they have such a kit… and that they are providing such good support!

Hi Leon,
I was pretty active on that other thread about AC300 and my transfer switch not working (AC300 wouldn’t power back up when power restored). I have a Protran2 and am now curious about “simply change the 15 amp circuit breaker in the manual transfer switch to a 15 amp AFCI breaker.” 1/3 of my circuits are AFCI. Is Reliance telling you that you should have a matching type breaker in the Protran2 for the type of breaker that’s in the main panel?


Here’s what Reliance told me:

Hi Leon,

Not it will not eliminate the Tripping. The AFCI breaker WILL trip with either the ProTran/1 or the ProTran/2 But with the ProTran/2 you have the option of replacing the breaker in the transfer switch since it is the same type in your main panel. The breakers in the house protect the circuits during normal power; the circuits in the transfer switch protect the circuits during generator power. AFCI in the house panel has nothing to do with generator operation since not in the path, only the breakers in the transfer switch.

With the ProTran2 you can do one of 2 things.

  1. Wire the breakers just like the other breakers and the outlet it is fed by will function as a regular outlet in Generator mode.

  2. Install a neutral kit and purchase another AFCI breaker and install it in the ProTran/2.

With option 1-The AFCI will trip and all you need to do is reset it once main power is restored. With option 2- there is the extra cost of the AFCI Breaker and Neutral kit, but the circuit is still protected when in Generator Mode.

With the ProTran/1 there is no other option, since they do not make a Push to Reset Breaker in the AFCI variety.

There is no way around the AFCI sensors tripping the breakers, when the transfer switch is on the “load side” of the AFCI breakers. That is the only way these Pro/Tran style transfer switches work, they are in between the house breakers and the loads.

If you have any further questions, please contact us.

Guenter Wiedemann bro-dmed

Technical Support


110th Anniversary Logo

Thanks Leon! Did they explain what a “neutral kit” was? I do not see that on their website. I may have to ping them to learn more… but I’m wondering if this would help those of us that are stuck w/ transfer switches that don’t work w/ the AC300.


I am not knowledgeable enough to explain the neutral kit and would advise that you ask an electrician for an official explanation. I believe that the AC300 has a “floating neutral” and that plays a part in why it is needed.

You can also email or call Reliance and ask them. They responded to my inquiries within 1 day.

As far as my AC300 is concerned, it works with the transfer switch without any problems except the afci breaker on the main panel has to be reset manually when grid power comes back on. The gfci breakers in the main panel do not trip when I switch to backup power so I do not have to reset them in the main panel when grid power is restored. I only have 2 afci breakers in my main panel. No other problems with my AC300 or ProTran manual transfer switch.


In order to have a AFCI or gfci work with these individual circuit type transfer switch and not have tripping you can install AFCI or GFCI type wall box devices and replace the AFCI or GFCI breaker with normal type. The reason is Many ( not all AFCI ) require the neutral to feed through the breaker for sensing of the current. In the case of a GFCI breaker this is not an option. In either case the breaker will trip when power is restored by the utility. If you are not home you will loose power to those circuits.
This is a stupid design if you have AFCI or GFCI breakers.

Best thing is to use a interlock device or a whole panel transfer switch and power the whole panel.

My 2 cents.