I bought some metal receptacle boxes at Lowes. They do not have grounding screws. When I install the receptacles, I will of course attach the ground to the ground screw on the outlet. Will the contact between the yoke and the box be sufficient to ground the box?
That is a contentious question. Certainly it will ground the box; however your inspector might not think so. Better quality outlets have a fancier hole on them to ensure a good ground; they should meet the code requirement, while the cheaper ones may not. Personally I ground both if the wire situation allows.
No, because when you remove the outlet the box will no longer be grounded. If you ground the box (you'll have to add a screw or a special UL-listed clip) you might not have to ground the outlet if the outlet has a little copper spring on one of the screws and is listed as "self grounding".
I usually wrap the ground wire about 270° around the screw in the box and then continue on to the outlet. I learned that trick here. :-) It works better than using a wirenut.
Those ground clips are hard to use IMHO and not worth it.
You can always use plastic boxes and then you don't have to ground them.
Bob
You can also get those screws in green with a short piece of green wire pre attached. At better supply houses. I know it will be more expensive than just using a clip or screw with you own piece of scrap wire but time is money and it makes a nice neat job.
Some of those can be seen here
I hadn't seen those before, and can see they would be real useful at times. Unfortunately I could not spend $0.80 on something that is otherwise nearly free.
I bought a box of them years ago, i will probably never run out as I now use mostly plastic boxes.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.