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In the master bedroom on one wall there are two receptacle that when tested shows “open ground”, I have replaced the receptacle on both (with new tamperproof receptacles) and while doing that checked to ensure there was a “ground” wire connected from the receptacle to the box (see image below). One thing to note – the room is aluminum wiring (but so are most of the house and no other receptacles have this issue).

enter image description here

At this point I am not sure what could be causing it, any suggestions? Thanks,

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Well, you either have:

  • No connection at the box despite appearing to have one (quite possible with aluminum wiring if the appropriate methods are not followed, from what I understand - but I have limited personal experience there)

or

  • the ground wire to those boxes is broken or not connected somewhere between those boxes and the main panel. Which actually makes lots of sense if you have two boxes in this state; probably one is connected to the other, and the wire is broken or not connected to the one that the other connects to.

I trust that as an aluminum wiring house owner your new receptacles are marked as suitable for aluminum wire?

Edit: No? Seriously?

As @Speedy Petey says, that really isn't an acceptable alternative to using the correct receptacles. House fires are not much fun. As for tracking down the problem, if this end is connected properly, you need to check the far end of the wire for a proper connection - you may find that you can identify which outlet is "next in line" by identifying the power wires feeding the probelm outlets - look there for a poor connection between the two ground wires.

@Chief Two Pencils seems to be failing to observe that you have aluminum romex with a ground wire - the problem is not a lack of ground wire, it's a lack of that ground wire being connected at some point.

You are failing to understand that the connection to the box does not "magically ground the outlet" - the box is being grounded (or rather, should be) by being connected to the ground wire coming from the cable. That wire is not connected all the way to the main panel ground from the two problem outlets. You, or a competent electrician (I'd really have doubts about continuing to use one that suggest that anti-ox paste is an adequate substitute for using CO/ALR or COALR marked devices) need to track down where that lack of connection is happening, and fix it, with a connector approved for use on aluminum wire (and it may well not be connected now becasue it was not connected with a suitable connector, or not properly prepared.)

The US CPSC advocates a more through approach of pigtailing copper wire to the ends of the aluminum wire with an approved connector to eliminate the aluminum connection fire hazard in a permanent fashion. Then you can use nice normal Cu-only connectors.

This is not a place for "creative" solutions. The house you burn down may be your own.

  • they are not, but I am adding anti-oxidant on all the connections as recommended by my electrician - will need to do it every couple of years... – Jonathan Feb 3 '15 at 21:59
  • So if the wire is broken, what can I do? I thought that just connecting a wire from the receptacle to the BOX itself would be enough of a ground ... what are my options? – Jonathan Feb 3 '15 at 22:00
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    Simply adding the anti-ox paste is NOT an acceptable alternative to using CO/ALR devices. – Speedy Petey Feb 4 '15 at 0:04
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    @Jonathan, in some instances that would be enough. For example a complete run of EMT connected to a metal box would provide a ground back to the panel. This is by design so that all metal parts are protected from being energized. However, in a house with romex cable, there's not metal to be bonded; the wire isn't metallic. So, you either need a ground wire in the cable to connect to the box which jumpers to the recept or it can't be grounded. In that case you either use ungrounded or GFCI recepts. – ChiefTwoPencils Feb 4 '15 at 3:34
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    I probably wouldn't have even asked if the outlets were CO/ALR rated, it never would have occurred to me that someone familiar with aluminum wiring wouldn't be aware of the dangers of using non-rated outlets. If it were my house, I'd have an electrician with AL wiring experience check all of the outlets, switches, and the service panel to look for more CO/ALR problems, and do the pigtailing where possible. – Johnny Feb 4 '15 at 21:02
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In the photo, does the bare ground wire run continuously from the Romex, under the screw, to the outlet? Or is that a shorter piece of wire just running from the outlet to the box?

In any case, the box is not grounded, based on what you've shared. Take a voltmeter and test between your hot and ground wire in the Romex. You should see ~110V. If so, you've got an easy fix at the box, one way or another.

If you don't see voltage between hot and ground, (or possibly between hot and the box, if the box is grounded -- which I doubt here) then there's nothing you can do at this end to fix it. You'll need to trace back to the breaker panel and find where you've lost the ground. You might start at the panel, or the next outlet (closer to the panel) from the suspect outlet. This is tedious work, but probably will reveal a bad connection somewhere along the way.

An alternative is to pull a new wire. If you have good access, this isn't the worst thing in the world, and could avoid a lot of troubleshooting.

I'm not qualified to give advice. Follow my advice and you'll probably die. You've been warned.

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