Hello: This is probably such a basic question, I'm a bit embarrased to ask, but let me try:
I am a homeowner, and wish to install a GFI type outlet in an existing metal "switch" box located in drywall/plasterboard. The box is the typical one used for either a wall switch or double outlet. The GFI double outlet I bought in the hardware store leaves Very little room between the side terminal screws, and the metal box wall. Enough so that I'm concerned. I understand that the plastic boxes are legal in my state, so I'm thinking of removing the metal box and installing the GFI in a plastic box. Good idea? Comments? I have also been wondering a bit more regarding plastic boxes in general, as I've never used any. Mainly, what does one do with the ground wire in the NM cable(not the neutral) when plastic boxes are used, and the switch or outlet does not have an additional (the usually green one) screw for it?
Bob, If you install a GFCI in a plastic box, the ground conductor will terminate to the receptacle. The plastic box does not need to be grounded. A metal box would need to be grounded either by attachment to a grounded receptacle or direct connection to the grounding conductor. The acceptability of the grounding of the box by the receptacle can be iffy, but don't worry if you use a plastic box. Removing the old box without tearing up sheetrock may be difficult. If you are careful you may be able to use a mid size or jumbo plate instead of having to patch sheetrock. Have you seen the old-work boxes with the ears that flip out to secure the box to the sheetrock? They are really handy, are larger than standard metal boxes, and sometimes the damaged area of the original sheetrock hole needs to be removed anyway for the larger box. Lowes and Home Depot sells them.
Before you start to remove anything in the old installation make sure you know what is involved in removing the old box. Some have two nails going all the way through the box and can be removed by cutting the nails inside the box with a pair of diagonal cutting pliers(dikes). If there is a bracket that is on the outside of the box you may need to tear up sheet rock to get to the nails or screws or with care you can push a screwdriver or heavy scraper between the bracket and wall to break the head off or pull out the nail or screw.
A simple solution is to get a GFI box extention. You are going to have to check with an electrician or mabe an electrical supply house will sell you one. It is a hard plastic extention that ends up with the recp. sticking out about 1/2" from the wall. There is an old style metal box that has the back corners cut at a 45 deg. and they barely allow a regular recp. to fit but these extentions allow you to put in a GFI. They have got me out of many a box change. If you need more info e mail me. When I order them I just ask for the GFI extentions. My supplier knows what I am talking about but I have no idea who makes them or what there proper name or model # is but if you need more info I can get it for you. BTW you will need 2" or better 6/32 screws to install the GFI w/an extention.
[This message has been edited by gto6t7 (edited 01-10-2001).]
A simple fix (assuming that you have the depth) would be to tape around the Receptacle once or twice. Most GFI's I've seen have slightly recessed screws on them. If you look close you may see that the screws are further away from the metal box than you think.