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deere2440 03-08-2008 08:31 PM

ground question
 
my house has some old outlets with no ground. I want to know how dangerous this is and what I can do about it without tearing out my walls? I have recently had some power surges and the power company said their neutrals in the transformer were bad and replaced them. But I am still a little worried about my outlets.

chris75 03-08-2008 08:36 PM

most household appliances dont even have a 3 prong cord, so I would just install gfci receptacles if you do happen to need one somewhere... And unless your house is wired with knob and tube your boxes are grounded as long as the connections are tight all the way back to the panel.

wire_twister 03-08-2008 08:52 PM

[quote=chris75;105666]most household appliances dont even have a 3 prong cord, so I would just install gfci receptacles if you do happen to need one somewhere... _-And unless your house is wired with knob and tube your boxes are grounded as long as the connections are tight all the way back to the panel.[/quote]

Chris, unless the OP house is wired in conduit, Greenfield, or romex that has a grounding conductor the boxes are not grounded. The best he can do in that case, without rewiring, is install GFCI receptacles.

chris75 03-08-2008 09:27 PM

[quote=wire_twister;105670]
Quote:

Originally Posted by chris75 (Post 105666)
most household appliances dont even have a 3 prong cord, so I would just install gfci receptacles if you do happen to need one somewhere... _-And unless your house is wired with knob and tube your boxes are grounded as long as the connections are tight all the way back to the panel.[/quote]

Chris, unless the OP house is wired in conduit, Greenfield, or romex that has a grounding conductor the boxes are not grounded. The best he can do in that case, without rewiring, is install GFCI receptacles.


You dont feel the BX after 1959 can be used as a legal ground?

gold 03-08-2008 11:02 PM

there may or maynot be a ground present. at one time the ground would have been wrapped around the nonmetalic cable and clamped, or brought into the box and wrapped around the clamp screw. The best way to tell is with a tester.

OP take a cover plate off and test from hot side to metal box, if you have the same EXACT voltage as you do between hot and nuetral then adding a jumper in between the box and the ground screw on the new device would be exceptable, although splicing the exhisting ground to a pair of jumpers( one to the box and one to the device) would be better.

if there is no ground present or insufficient ground (wich may be another issue) then replacing the old "2 prong" device with a new "2 prong device is allowed.

you can also replace them with gfi's but this can be expensive and annoying.
if the devices look old and painted replacing them is a very good idea it also gives you a chance to vaccuum the dust and cob webs out of the box, just make sure your terminations are tight and the wire is wrapped all the way around the screw.


side note: I have seen the ground wires taken out of the box through the same entry the nm comes in through and landed on the outside of the box.

I reccomend a digital tester for this.

.

Speedy Petey 03-09-2008 06:42 AM

Quote:

Originally Posted by chris75 (Post 105678)

You dont feel the BX after 1959 can be used as a legal ground?

Not if it doesn't have the thin aluminum bond strip running inside.

deere2440 03-09-2008 06:49 AM

So If no ground is present then gfci's are the answer?

Speedy Petey 03-09-2008 07:08 AM

IMO yes.
Or use two prong receptacles.

A GFI installing in a situation like this will fool a surge strip into thinking there is a ground yet still be safe.

chris75 03-09-2008 09:41 AM

Quote:

Originally Posted by Speedy Petey (Post 105723)
Not if it doesn't have the thin aluminum bond strip running inside.

Thats my point, thats when they started installing it... :)

wire_twister 03-09-2008 04:33 PM

The OP never said how the house was wired, I was merely saying unless some method other than 2 conductor nm or knob and tube was used there will be no connection to the grounding electrode.

Speedy Petey 03-09-2008 04:52 PM

What does the grounding electrode have to do with it?

jrclen 03-09-2008 06:05 PM

Most of the old BX I work with has no aluminum strip nor an equipment grounding conductor, so it is not an acceptable ground. The sheath will show a DC path on your ohm meter, but to AC current the spiral sheath is a high impedance path (inductance like a choke coil or transformer winding) which will fail to conduct enough current to operate the over current protection device. In addition, those spirals can then heat up like a heater element and cause a fire. Never use this BX for an equipment ground.

deere2440 03-09-2008 08:52 PM

bought a half dozen GFCI recepticals today. Now I just have to go around the house and replace the ones that arent grounded. These puppies are expensive I will have to say.

Pudge565 03-09-2008 10:19 PM

Don't forget to mark all ungrounded GFCI's as NO EQUIPMENT GROUND use the stickers that come with them and also do the same thing with any subsuquent recepticals down the line.:thumbsup:

220/221 03-09-2008 10:22 PM

Quote:

Originally Posted by deere2440 (Post 105976)
bought a half dozen GFCI recepticals today. Now I just have to go around the house and replace the ones that arent grounded. These puppies are expensive I will have to say.



Good luck jamming them safely in your existing boxes.


GFCI breakers are the way to go.


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