To expand on the question I'm trying to put these AFCI's and GFI's everywhere I need them, but nowhere I do not. Also my experience with AFCI's up to this point have been poor. They trip when the humidity in the room drastically changes and I don't like the idea of having an alarm system tied to it.

Below is my understanding of how the breakers need to be allocated based on NEC 2020. Note that these four bedrooms will be occupied by four unrelated students, who will likely have their own computer, TV, gaming console, etc. For this reason it seemed practical to give each bedroom its own breaker for receptacles. That being said, I will happily take any scrutiny about this arrangement as long as it conforms with 2020 regulations. Philly has recently cracked down on slum lords, especially when it comes to student housing.

  • Furnace Igniter 1 x AFCI
  • Water heater IG 1 x AFCI
  • 4 x Bedrooms 4 x AFCI breakers
  • 2 x Bathrooms 2 x Duel function breakers (or AFCI w/ local GFI)
  • 2 x Kitchen cntr 2 x Duel function breakers
  • 1 x Refrigerator 1 x AFCI
  • 1 x Dishwasher 1 x AFCI
  • LR + Hall +kit 1 x AFCI
  • 1 Outdoor outlet 1 x GFCI
  • 40A Dryer 1 x standard trip 240V 2 pole
  • 50A Range 1 x GFI 240V 2 pole (standard trip for 2017)
  • Sec/Fire panel 1 x standard trip

    NOTE I have never seen anything about this in the NEC, but I was always told (by philly electricians) that inspectors want to see kitchen counter receptacles divided into a minimum of 2 circuits and this is in addition to wall receptacles.

    NOTE I believe I read GFI's were required on 240V for breakers >= 50A

This post is similar to this one, but I still had many unanswered questions. Mainly the title question. Where should arc fault breaker not be used?

  • 1
    FYI, I prefer AFCI breakers and GFCI outlets for bathrooms and kitchens. Those are places where it's likely to trip a GFCI by accident, and it's convenient to reset locally instead of having to go back to the panel. Also reduces calls to the landlord for nuisance trips. In contrast, I prefer the GFCI function to be in the panel for daisy-chained outdoor circuits so that you don't have to find/remember which outdoor outlet has the reset button. In your case with 1 outdoor outlet, I'd go either way.
    – longneck
    Commented Mar 9, 2020 at 18:03
  • First, NEC 2020 isn't here yet, and you need to comply with the NEC your permit calls out. I would ask the AHJ if metal conduit to the recep is an acceptable substitute for AFCI, and do that in the kitchen. Is the range a 3-wire connection? @longneck Code requires the panels be tenant accessible. So commons space not 1 student's bedroom. Best place is a hallway, since it naturally meets the "keep clear" requirements. Commented Mar 9, 2020 at 18:44
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    In my locale 4 unrelated people (students or not) is classified as a rooming house not a typical residence and falls under its own local code compliance and regulatory rules. I mention this as NEC rules may or may not be sufficient.
    – mikes
    Commented Mar 9, 2020 at 18:47
  • 2
    Unless you live in Massachusetts you are on the 2017 code according to the latest January 2020 update I could find. Depending on your state you may be on a code version of 08 or not even have one, I don’t worry until October that’s when my state adopt the 2020 and even then there are many exclusions.
    – Ed Beal
    Commented Mar 9, 2020 at 18:56
  • 1
    The 2 small appliance circuits for kitchens is a requirement 2 ea 210.11.c.1. 20 amp and GFCI protection 210.8.6 in the 17 code also only 120v receptacles require GFCI in 17 code 210.8.A .
    – Ed Beal
    Commented Mar 9, 2020 at 19:11

1 Answer 1


Since you have separate appliances, it's a NFPA 72 residential (combination) system, and thus 760.41 and its associated exceptions apply

You are correct that NEC 760.41(B) waives GFCI and AFCI requirements for power sources to fire alarm systems; in fact, it outright prohibits the use of GFCIs and AFCIs on fire alarm system power sources:

(B) Branch Circuit. The branch circuit supplying the fire alarm equipment(s) shall supply no other loads. The location of the branch-circuit overcurrent protective device shall be permanently identified at the fire alarm control unit. The circuit disconnecting means shall have red identification, shall be accessible only to qualified personnel, and shall be identified as “FIRE ALARM CIRCUIT.” The red identification shall not damage the overcurrent protective devices or obscure the manufacturer's markings. This branch circuit shall not be supplied through ground-fault circuit interrupters or arc-fault circuit-interrupters.

However, in order to apply this, we need to know what sort of fire alarm system we have, and in order to do that, we need to turn to NFPA 72, which is the governing code in the USA for fire alarms of all sorts (from single station smoke detectors to massive systems that link together multiple high-rise buildings).

In the SimpliSafe's case, the system, in order to perform its fire alarming function, requires:

  • At least one compatible smoke detector (initiating device)
  • The base station/central hub (fire alarm control unit)
  • And some sort of sounder (notification appliance)

Since we have separate parts involved, we know it doesn't fit the definition of a single station alarm as those are defined as all-in-one units by NFPA 72:

3.3.245 Single Station Alarm. A detector comprising an assembly that incorporates a sensor, control components, and an alarm notification appliance in one unit operated from a power source either located in the unit or obtained at the point of installation.

And, since we're not dealing with single station alarms, we know it's not a multiple station alarm either:

3.3.149 Multiple Station Alarm. A single station alarm capable of being interconnected to one or more additional alarms so that the actuation of one causes the appropriate alarm signal to operate in all interconnected alarms.

From that point, we can deduce that it is a fire alarm system:

3.3.95 Fire Alarm System. A system or portion of a combination system that consists of components and circuits arranged to monitor and annunciate the status of fire alarm or supervisory signal-initiating devices and to initiate the appropriate response to those signals.

and from the fact it's in a dwelling unit (house), we can then determine that it's a household fire alarm system: Household Fire Alarm System. A system of devices that uses a fire alarm control unit to produce an alarm signal in the household for the purpose of notifying the occupants of the presence of a fire so that they will evacuate the premises.

that also happens to be a combination system:* Combination System. A fire alarm system in which components are used, in whole or in part, in common with a non-fire signaling system.

as it can perform the other functions expected of a household alarm system, such as burglary alarming.

As a result of this, since we have a fire alarm system using a separate fire alarm control unit:

3.3.92* Fire Alarm Control Unit. (FACU) A component of the fire alarm system, provided with primary and secondary power sources, which receives signals from initiating devices or other fire alarm control units, and processes these signals to determine part or all of the required fire alarm system output function(s).

, we then treat the power source to the fire alarm control unit as a power source to a NPLFA circuit, which invokes NEC 760.41. (Granted, NFPA 72 itself is evolving in this regard, and as of 2016, best I can tell, is not as stringent as the NEC is here.)

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