Old Electrical Receptacle and Ground

[redbrickhat]

I recently repaired and upgraded two old 2-prong electrical receptacles
to 3-prong. Both receptacles had 2 wires and grounded boxes.

One of the receptacles is now powered and grounded properly. The other
receptacle is powered correctly but has a weak ground -- when I used a
voltage tester, the power light was bright but the ground light
flickered.

I think that the ground fault is either between the metal cable and the
box or between the screws of the receptacle and the box. The metal bars
of the box where the receptacle screws in are very rusted and corroded.


Has anyone had similar problems with this type of weak ground in a
old-style grounded box?
Do you think trying to de-rust the box will help?



Thank you

 

[John Fields]

I recently repaired and upgraded two old 2-prong electrical receptacles
to 3-prong. Both receptacles had 2 wires and grounded boxes.

One of the receptacles is now powered and grounded properly. The other
receptacle is powered correctly but has a weak ground -- when I used a
voltage tester, the power light was bright but the ground light
flickered.

I think that the ground fault is either between the metal cable and the
box or between the screws of the receptacle and the box. The metal bars
of the box where the receptacle screws in are very rusted and corroded.


Has anyone had similar problems with this type of weak ground in a
old-style grounded box?
Do you think trying to de-rust the box will help?

 

[RBM]

You're dealing with near 100 year old wiring so I wouldn't be expecting to
much from the steel cable, however, try taping a 10/32 threaded hole in the
box and attaching a ground wire from the box to the outlet. Also try
tightening up on the cable clamp if it's accessible

 

[Beachcomber]

I recently repaired and upgraded two old 2-prong electrical receptacles
to 3-prong. Both receptacles had 2 wires and grounded boxes.

One of the receptacles is now powered and grounded properly. The other
receptacle is powered correctly but has a weak ground -- when I used a
voltage tester, the power light was bright but the ground light
flickered.

I think that the ground fault is either between the metal cable and the
box or between the screws of the receptacle and the box. The metal bars
of the box where the receptacle screws in are very rusted and corroded.


Has anyone had similar problems with this type of weak ground in a
old-style grounded box?
Do you think trying to de-rust the box will help?



Thank you

A weak ground is essentially no ground, as far as ground protection is
concerned. Also, check your tester, as the "flickering" could be a
neon lamp going bad. They do make more expensive testers though,
that can simulate higher ground fault currents. Can you protect the
circuit with a GFCI mounted somewhere upsteam? Might be a good idea.

Beachcomber

 

[Homer J Simpson]

One of the receptacles is now powered and grounded properly. The other
receptacle is powered correctly but has a weak ground -- when I used a
voltage tester, the power light was bright but the ground light
flickered.

Assuming BX I'd pull the box and cable out and try to make a good clamp
ground to the BX cable or the ferrule it attaches to. ADD that to your
existing ground (don't rely on it alone).

 

[Phil Allison]

** Groper alert !

One of the receptacles is now powered and grounded properly. The other
receptacle is powered correctly but has a weak ground -- when I used a
voltage tester, the power light was bright but the ground light
flickered.

** Such a " voltage tester " cannot be used determine either the safety or
integrity of an AC power outlet.

That can only be done by REMOVAL and careful visual inspection of the AC
outlet and its associated wiring by an experienced person.



........ Phil

 

[[email protected]]

** Groper alert !



** Such a " voltage tester " cannot be used determine either the safety or
integrity of an AC power outlet.

That can only be done by REMOVAL and careful visual inspection of the AC
outlet and its associated wiring by an experienced person.



....... Phil

Also, since this is very old wiring and the grounding is in question,
I'd switch to GFCI.