Dead GFCI outlet(s), wire is live

Question

Summary

GFCI outlet is 'dead' (no power, won't test or reset), when the wire feeding it is live. Outlet was working yesterday. Swapped outlet with another GFCI (that had previously been working) and it behaves the same.

Details

I had to rebuild a piece of my house that had a (working) GFCI outlet on it. I purchased a new GFCI outlet, as the old one had a piece of broken plastic. I wired it up, being sure to put the white wire on the silver screw, black wire on brass, and avoiding the terminals with the sticker over them used to feed other receptacles. The outlet worked fine for a day. In case it matters, it's almost exactly this model:

Workers waterproofed near the outlet all the next day. (EPDM sealing a planter box.) It happened to be quite cold in the house for 6 hours, windows and doors open to 40° weather for ventilation. Presumably this paragraph is irrelevant.

Today, the outlet does not work. No power to items, no indicator light, pressing either RESET or TEST does nothing. The circuit breaker has not been tripped. An AC tester indicates power on the line.

I swapped the outlet with the previous GFCI outlet (which was working fine when last used). Same behavior (though the previous 10-year-old outlet never had an indicator light).

I removed the outlet, made the circuit breaker live, and used a multimeter on the bare wires. Measurements are:

• Hot-to-neutral: 121.4V (Black-to-white)
• Hot-to-ground: 121.4V (Black-to-bare)
• Neutral-to-ground: 0.0V (White-to-bare)

When I attached the GFCI outlet and measured the line terminals:

• Nothing plugged in: 121.4V
• Known-working lamp plugged in: 119.5V

What is going on with my power? Are both outlets coincidentally dead? Am I miswiring them? Most importantly: how do I fix this?

---

Edits:

• I've already discarded the box for the the new GFCI outlet, but it says on it:

  Leviton
  INSP.1J460
  17456-037 ZR 2
  

  …and on the other end is a nicely printed UL sticker:

  UL LISTED
  GROUND FAULT CIRCUIT INTERRUPTER
  CLASS A
  2 POLE UNIT
  20A 125V 60HZ
  ISSUE NO. 0045578
  LEVITON MGF.CO.INC
  O
  

  It may be a "Leviton X7599-E SmartlockPro Slim GFCI Tamper-Resistant Receptacle with LED Indicator, 15-Amp, Black", based on searching for features and images, but I'm not certain of this.

• I forgot to mention, in case relevant, that I'm using a metal waterproof outdoor box for the outlet (this one), which has a grounding screw in it that I've attached to the ground wire. (Ground wire is clamped in the middle to this screw in the box, and then continues to be attached to the outlet.)

Answer 1

Best I can tell, it's time to buy another GFCI (the correct one, this time -- hopefully, the third time's the charm)

There are four problems here:

1. The old GFCI finally died (at power on, likely) and the new GFCI is likely DOA. Easiest fix is to try getting another GFCI and putting it in.
2. Your new GFCI was the wrong part -- you need a weather-resistant receptacle in a damp or wet location these days (NEC 406.9), and yours isn't. Leviton's W7599 is the equivalent of what you have in a Weather Resistant model, BTW (as of this post, at least).
3. Receptacles in wet locations require a while-in-use weatherproof cover or "bubble cover" these days, such as this. This helps keep rain out even under wind-driven conditions, no matter whether stuff's plugged in or not.
4. Even weatherproof boxes need to be pressure equalized (via a drainage hole in the bottom) in order to keep pressure differences from driving water through even the slightest imperfections in seals and to give any water that does get in a path to escape. This is allowed as per 2014 NEC 314.15:

314.15 Damp or Wet Locations. In damp or wet locations, boxes, conduit bodies, and fittings shall be placed or equipped so as to prevent moisture from or accumulating within the box, conduit body, or fitting. Boxes, conduit bodies, and fittings installed in wet locations shall be listed for use in wet locations. Approved drainage openings not larger than 6 mm (¼ in.) shall be permitted to be installed in the field in boxes or conduit bodies listed for use in damp or wet locations.

See also BSI-004: Drainage, Holes, and Moderation for a good explanation as to why even the most snugly sealed enclosures need weep holes. So, if there isn't a small hole in the bottom already, drill a ⅛" hole in the bottom of the box, as per NEMA bulletin 110 and the aforementioned NEC clause.