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I've a new basement kitchen 20amp circuit (with regular 20 amp breaker) that has a blank face AFCI (near the panel), GFCI outlet (first outlet in the kitchen) and regular outlet at the end (used a 15 amp in a 20 amp circuit for testing purposes only. Did not have a 20amp outlet). See picture below to see how I wired them (note: AFCi was blank face).

  • When turned on the breaker and reset the AFCI (comes as off mode), small explosion took place in the GFCI box.
  • Turned off the breaker and checked to and saw the black line wire to GFCI was severed, in side the box. Checked the wiring and it was correct (already have 4 other new circuits that are protected by either AFCI or GFCI, but not both in the same branch circuit).
  • Then disconnected the regular outlet, repaired the connection and tried again (with AFCI and GFCI only). Seemed to have been working ok.
  • Used an outlet tester (Kline tools see below for pic.) with lights to test them. When both are on tester indicates it was wired correctly. When the AFCI is off and GFCI is on, tester plugged into GFCI was off. When AFCI is on and GFCI is off the test lights indicate the hot and ground were reversed.
  • Can anyone shed some light into why 1) the small explosion happened? 2) the tester lights indicate that ground and hot are reversed? Btw, I did check the connections yet again and they are correctly wired, no cuts and not touching.
  • Also, I did the above testing with a table lamp plugged to the GFCI and the lamp was off when either AFCI or GFCI was set to off.

If the picture does not show the correct way to wire, how to do it. A picture is better, with explanation.

enter image description here

enter image description here

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    Thanks and corrected it. Also added some more information to make it clear as much as possible. – Nick Apr 11 at 21:19
  • Where did the GFCI come from? A local shop? Bargain unit on Amazon? – Harper - Reinstate Monica Apr 11 at 21:22
  • All items are purchased from HomeDepot, Leviton and new. – Nick Apr 11 at 21:44
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    Just to cover a base... you do understand that the wire run from panel to first deadfront AFCI must be metal-jacketed, right? Either armored cable or a metallic conduit. I'm a big fan of a short stretch of EMT from panel to a 4-11/16" box where I put 2 circuits' worth of AFCIs. – Harper - Reinstate Monica Apr 12 at 17:28
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Remember: the run from service panel to first AFCI must be either metal-jacketed cable or metal conduit.

I would find that drawing very confusing. It's always a struggle to show neutral on a white background (hint: don't), but what ere they thinking? White is the legally required neutral color, and black is the conventional hot color. So that bung drawing is certainly inviting a hot-neutral reverse sort of mistake.

Anyway, it sounds like your "ka-boom" happened either due to a wiring error, or due to a ground wire touching a hot terminal screw on the "Line" side (if it was on the "Load" side the GFCI would've tripped obviously). It became a "race condition" between the AFCI detecting an arc fault, the circuit breaker tripping for overcurrent, or the short condition burning itself out. It sounds like the latter won.


Those 3-lamp testers are rather useful for doing 3 "neon light tester" tests simultaneously... but the sticker's opinion of what the problem is, is so laughably wrong that I call them "Magic 8-ball" testers.

enter image description here

What you have is outer yellow (hot-ground) and red (neutral-ground) lights lit. That is a typical sign of a lost neutral, with a load plugged in and turned on that is effectively connecting the hot to the dead side of the neutral.

Here's that drawing, fixed. The creator of that drawing should not be giving AC mains wiring advice in North America.

enter image description here

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  • Thanks Harper. Is the wiring diagram above correct, assuming the black line represents neutral? Otherward, it should work if I were follow it? Next, how to fix the lost neutral in this scenario? – Nick Apr 12 at 1:00
  • I'm watching some videos and you seem to be correct. I'll trouble shoot more of the wiring and will try to diagnose it. Any other suggestion let me know. Thanks again. – Nick Apr 12 at 1:34
  • @Nick I fixed the diagram so it isn't wrong. The routes were correct but the colors were a recipe for failure. – Harper - Reinstate Monica Apr 12 at 7:33

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