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I've been googling, searching this community and looking over the 2017 NEC codebook (which can be very confusing) and I've come to the conclusion that a crystal clear, no nonsense, straight forward answer to this question doesn't exist. I don't know how, I must have overlooked it, but best I can tell, the information (in a very clear format) isn't out there. So could someone please help me out here? (sorry for the preface, I'm used to being accused of not doing research/making duplicate questions so I wanted to, more or less, show the steps I took before I decided to ask a question here).

AFCI breakers are significantly more expensive than AFCI receptacles. (Scratch that, it's the GFCI breakers that are significantly more expensive than the receptacles...well regardless, I'm still curious about this and it would be good to know!) and I had the idea of installing an AFCI blank face outlet (which, I can't imagine what other use a blank face outlet would have honestly) right beside the breaker box before heading out to the circuit so that the entire circuit would be protected.

Something like this: https://www.homedepot.com/p/Leviton-20-Amp-SmartlockPro-Arc-Fault-Circuit-Interrupter-AFCI-Blank-Face-Outlet-White-AFRBF-W/301767741

My idea was to buy a metal multi-gang box (or more) and mount them beside the breaker box, then run conduit to them (short runs) and have the circuit go through these boxes which will have blank face AFCI receptacles (one per each circuit)

The only crystal clear piece of information that I have though is that from the box, to the first receptacle, it must be armor clad cabling, or in metal conduit and the first box must be metal and grounded. This is where I get confused though because I've seen a couple of people state that every single box downstream of the AFCI receptacle must be metal also. I've seen that specifically mentioned, but I've also seen it omitted (only mentioning conduit to the first box and the first box being metal). Considering the entire reason for an AFCI in the first place, it makes sense that they require armor clad cabling or conduit up to the first AFCI protected receptacle, as well as that box being required to be metal. But I don't understand why every box downstream must be metal too since, for all intents and purposes, this receptacle would be acting exactly like an AFCI breaker, which I don't believe I've seen anybody say that device boxes and junction boxes must be metal on an AFCI breaker protected circuit.

I didn't see anything in the NEC code book though, that was very clear that all receptacles downstream must be in a metal box, but the way they word things can be a little confusing so I could have misread/misunderstood. So I'm wondering if maybe somebody just made that assumption and said that but it's not actually required?

My concern is not about being code compliant, but rather safety. Obviously I must be at least code compliant, but it's like it was stressed when I was driving a truck over the road; Be SAFE and legal. Safety ALWAYS comes before being legal.

Thank you kindly for your help!

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    Why would you want to add AFCI protection next to the breaker panel? I can understand adding them to bedroom circuits (the original reason they were required) if you just want to upgrade everything (Not required by code for existing dwellings) the best place is close to the point of use. AFCI'S do have major down falls they do not work well with circuits on dimmers and electronic ballast ,variable speed motors or variable frequency drives in newer high efficiency motor driven appliances. Yes code can be confusing and local requirements can make it much more confusing. – Ed Beal Nov 19 '17 at 2:13
  • @EdBeal I wanted to install Blank Face AFCIs in place of circuit breaker AFCIs because I thought they were significantly cheaper. But turns out, it was the GFCI breakers that were more expensive. And I realize it's not required in existing dwellings, but I'd rather go by the stricter code because it's a lot safer. And if I just throw an AFCI outlet close to the point where I want to use it, yeah it's code compliant, but the run all the way to that first outlet is not protected. I've heard about the issues too, so I'm trying to be careful :\ – Soundfx4 Nov 20 '17 at 8:13
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The 4x4 box right next to the service panel is a great idea, and I do that myself a lot.

Nobody cares which wiring method you use downstream of the AFCI.

Between the service panel and the AFCI, the inherent problem is the AFCI would never* detect a problem on that stretch of wire. That is a vulnerability, so that is where they require metal jacketed cable before the AFCI if the AFCI is not a breaker.

So, use a better wiring method. I have to say, for wiring between a panel and a very nearby box, EMT is faraway the easiest way to do that IMO. Keep it shorter than 2 feet, whcich eliminates the wire derate for 5 or more circuits. Ideally use 3/4 conduit, which has room for more than 10 wires and will give easier pulling.

Go to a metal 4x4 x 2-1/4 box, and use a 2-GFCI lid with 1/2" of lift. That will give you plenty of practical room to fit wires. If needed use an EMT nipple to chain to another 4x4 box. An arc fault inside this heavy metal is very unlikely to successfully start a fire.

Use THHN wire on through the conduit. If the circuit can't easily be moved to terminate in the box, come back into the service panel with THHN and splice there. This out-and-back-in method has 4 wires in the conduit per circuit, so watch your conduit fills.

* Actually, AFCIs do have some ability to detect arc faults immediately before them. We recently had a Siemens AFCI breaker faulting because it was clipped into a GE panel, and the clip/bus was not quite compatible.

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    This is all great information, but to answer the question simply... The only requirement for metal cladding/metal conduit, is between the panel and the first box that contains the AFCI. After that point, you can use whatever wiring method you want. – Tester101 Nov 19 '17 at 1:00
  • To get clarification on the AFCI requirement: my house built 1971 and wired in NM plastic boxes has no AFCI protection. I was thinking about putting AFCI receptacles to protect the boxes in each bedroom, but not protect the receptacles on the other sides of walls in halls, living room, etc. so as to avoid nuisance trips from e.g., vacuum cleaner, electric space heater. What is this about metal boxes, and metal conduit ?! – Jim Stewart Nov 19 '17 at 12:43
  • What kinds of arcing scenarios are the code requirements for AFCI receptacles designed to neutralize? – Jim Stewart Nov 19 '17 at 12:50
  • @JimStewart the purpose of an AFCI is to protect from faulty wiring (think: nails, backstabs and ratty aluminum wire) especially under heavy load conditions e.g. Heaters. The method you propose is appropriate for GFCIs but defeats the purpose of an AFCI, since it would protect no wiring at all. – Harper Nov 19 '17 at 18:05
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    Harper is correct, AFCI were originally required in bedrooms to prevent electric blanket fires because electric blankets with all the flexing begin arcing, all the other uses for faulty back stabs, aluminum and nails through wires were added later. – Ed Beal Feb 8 '18 at 23:14
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AFCI was looked at and added to the code not for obvious fire such as heating blankets, AFCI protection was developed in code due to hidden fires, that is also why is was expanded.

The example of the blanket fire, will be easy to detect, specifically if fire detector placement is followed. (Will have to assume that a correct fire alarm detection system is in place) The issue is with Hidden fires, fires that can occur without detection for minutes, hours, or even days. Until it grows for so long, by the time detection occurs either from human or detection equipment escape is impossible or nearly impossible.

If your house was built in 1971, however, you do not need to meet the current code requirements. Unless you have a modifications, new construction, etc. in which your local AHJ is requiring to meet a newer code version from your Certificate of Occupancy.

If you wish to upgrade specific outlets to AFCI technology you can, as that would be bringing your house up in safety then to which it is required to meet. (There are people and even AHJs that will say that is "new" or Modification to the existing, however as long as you do not add an outlet, it is not, it is just a replacement of an existing or maintenance. As most outlet receptacles should be replaced every ~10 years.

The current technology AFCI will not trip most vacuum cleaners or space heaters, Unless the device is having a major internal problem. The largest problem with vacuum cleaners is that they are old and dirty, and this causing larger then normal arc events which fall into the signature of "bad" arcs.

Lets look at this from a your going to all this trouble, and WHY? To protect your family from Fire. AFCI protection is really adding fire detection to hidden spaces, in which electrical wiring or electrical supplied items are the cause of the fires from arc's that spread heat to nearby items or touching items.

The arcing scenarios are series arcs or parallel arcs. series are like a break in the same wire, a pinch of the same wire, etc. Parallel is line to line, line to ground or line to neutral, this is where the arc is occurring from one conductor to another.

In my experience, to answer this from an ease stand point and offering the most safety is to pay twice the amount of for the AFCI breakers, and replace them. (always recommend that an electrician do the work, but this is a DIY forum, so if you choose to DIY, always be safe and ensure the power is off) It is alot easier then running MC / pipe, and then wiring all those new outlets for each branch. But that is the other option that is pretty close to the same safety level is protect the cable from panel to that first outlet, and then that AFCI outlet will protect down stream. It will look messy and not clean however, not the way in my opinion for looks / resale.

Also a note on Harper statement "Siemens AFCI breaker faulting because it was clipped into a GE panel" this actually voids the UL listing on any panel.

There are no breakers that are UL LISTED to be in another manufacturers panels. This is a pet peeve of mine. What ever panel you have, the breakers HAVE to be the same manufacturer. I have found that most AHJs skip this fact or just are not aware. That is an example of Why, breakers have only been tested by UL in that companies boxes. *** I know someone will post a comment, BUT there are UL classified breakers. Those do not meet code, the code requirement is that UL Listed breakers are used in an UL listed enclosure. In my experience again, AHJ never pick up on this. The only people I have found that so far pick up on this are Insurance companies, so when your house does burn to the ground and you need that check to rebuild your life, I have found some insurance companies to deny, fight, etc. over this issue of mixed manufacturers in a panel.

If your electrical device trips the AFCI, ie vacuum etc. Go get a vacuum that doesn't. Again think of AFCI as a fire detection system, is my life and my families life worth it?

-Fire Protection Engineer JT

  • Can you give us a NEC citation on UL classified breakers not being allowed in panels they are properly classified for use in? – ThreePhaseEel Feb 14 '18 at 23:26
  • Welcome to DIY.SE! There's a lot of fluff in here (some of which should be comments on the question or a different answer) , which makes the actual answer in here hard to see. Could you edit it down to highlight the answer itself? – mmathis Feb 15 '18 at 14:31

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