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Electrical Wiring

wiring gfci and grounded outlets in old house

14 years ago

My folks house has bmx to most ( maybe all ) outlets.

Planning to install GFCIs. The insert/instructions shows to connect the ground via a wire to the grounding screw in the box and then 'pig tail' to another wire to the grounding screw on the GFCI.

The boxes in the home have the bmx attached to the box and the ground attached to the grounding screw in the box ( at least in some instance that I have seen .)

Can't I simply run a ground from the GFCI ground screw to the ground screw in the box ) why pig tail except to maybe make wiring easier ?) Or run the ground from the bmx to the ground scrw on the GFCI?

THEN when I add the 3 prong outlets --- wire from ground screw on 3 prong to box grounding screw ? or simply attach ground from bmx to ground screw on 3 prong outlet?

THANKS

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Comments (3)

sfjeff
14 years ago
I'm guessing that the install instructions are aimed at the use of NM cable ("Romex") where you need to connect grounds from:
* The box
* The GFCI
* The feed cable
* Any "downstream" devices
In this case, one generally would use a screw/wire from the box into a wire nut that collected together the cable and the outlet(s).

Assuming the insulation on the BX is still in decent shape, I'd use that approach. You can buy short grounding wires, with screws pre-installed in the end which makes the job a little easier if you have more than a handful of boxes to do.

I'm not completely sure where the other outlets are, but I'll assume in the same box. In that case, you'd take the hot and neutral to the back of the GFCI and the ground to the wire nut as well. Make sure your wire nut is rated for four #12 conductors (cable, box, GFCI, outlet) -- red or bigger, as I recall.

I'm not a licensed electrician, but last I checked there is no Code as to how to install the outlets. My personal choice is to put the ground lug up, so that if something falls against the wall (like a metal tape measure), it hits the ground lug, not the hot. For a sideways install, I put the neutral on top.
Ron Natalie
14 years ago
Neither the screw on the receptacle nor the one on the box is designed for more than one wire. That is the main reason you have to pigtail things. All three things: the box, the ground from the incoming cable, and the receptacle ground need to be connected togehter.
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rileyann, I don't think Joefixit had read the original posts about the ground wire. The truth is that I don't fully trust that ground wire - that's part of the reason for making a home run to the breaker box. If you don't feel comfortable making the connection in the breaker box, hire the whole job done. A professional will do a good job of getting it to the box, and getting it grounded properly. I think that running a new conduit (which is what would need to happen) may put the the job outside your current abilities. Just so you know, current code requires at least two 20 amp small appliance circuits in the kitchen that feed almost nothing else (the fridge can be on one of those, a kitchen clock outlet and an outlet for a gas stove are all that's permitted to be included with counter-top outlets - no lights and certainly not GD and/or DW). There's a little more to the code than that... but you can google it. I don't know if your remodel would obligate you to meet current code, but it's good to know what that code is. For sure if your counter-top outlets, GD, DW, and Fridge are all on the same circuit it needs the GD and DW split off. The circuit is over utilized even if there wasn't a rule about counter-top outlet circuits in the kitchen being kept separate. The point is you need to make a home run back to the panel and you probably need to hire it done.
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You can leave the grounded receptacles as is. Just install a GFCI type receptacle as the first one on each circuit and feed the rest from the load connection on the GFCI. Use the labels that come with the GFCI to indicate the GFCI protection and no equipment ground at each receptacle. The adapters ought to be outlawed and posession of them should at least be a flogging offense, IMHO Ungrounded lighting circuits are seldom as big an issue as receptacle circuits. Many appliances, tools, and other things have cords with a ground type plug indicating they should be grounded. The GFCI will protect you from shock with these things but in the case of electronic equipment, computers especially, a grounded circuit is almost a requirement to prevent equipment damage from a number of sources. Also, surge suppressors need the added connection to function properly. It wouldn't hurt to think about gradually upgrading all the receptacle circuits as you can, but no reason to hurry unless you get something requiring a ground.
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Thanks guys. The system consists of autonomous switch replacements throughout the house which 'listen' for pulses sent along the neutral line. Technology is called UPB and is very common in home automation. Effectively this would be like installing a nightlight replacement in the outlet or something like that. Very low power draw device that does not control any load. Admitted I don't understand the inner workings of the GFCI system. Home is 3 years old and there are probably 12 GFI outlets throughout the kitchen and island area. I just wanted to pull power from one of them, hoping to simply 'jump' or connect the gfci from this outlet as if it were never there. I appreciate the advice and warnings though. I certainly have no desire to make the home unsafe.
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"the first electrician was an inspector and knows his plug in testor doesn't work without a ground wire, therefore he thinks the gfci doesn't work. silly inspector!" The plug in tester is not even a reliable way to check a GFCI. The 'TEST' button on the face IS the recognized way. The small testers do not have adequate precision in the 'leakage' current they simulate. They are a 'meatball' way of verifying that a regular receptacle is on the LOAD side of a GFCI. They put a load from hot to ground to unbalance the current. No ground, no current, but it has nothing to do with the GFCI working correctly. They put the unbalance around the sense coil between the hot and neutral.
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brickeyee
14 years ago
You may find if the installation is old enough there is no tapped hole in the box to attach a ground wire to.
Sometimes there is not even a hole.

You will need a pig tail to connect the box to the GFCI receptacle.

Only if there is another ground wire present will it need to be connected also, creating more pig tails.

AC cable (what you probably actually have) uses the armor on the cable as the grounding conductor.
The box is already grounded by the cable clamp from the AC cable to the box.

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