[Pharon]

Hi everyone! I'm a registered electrical engineer from Boston, MA, and I stumbled onto this site because I was trying to figure out why some PVC boxes have green ground screws in them.

My house is full of knob-and-tube wiring, so I may be asking some questions in the near future about how best to fish wiring from one place to another.

Been in this industry for over 20 years and am amazed sometimes that there's still plenty to learn.

Anyway, happy to be here. :thumbsup:

 

[macmikeman]

Hi everyone! I'm a registered electrical engineer from Boston, MA, and I stumbled onto this site because I was trying to figure out why some PVC boxes have green ground screws in them.

My house is full of knob-and-tube wiring, so I may be asking some questions in the near future about how best to fish wiring from one place to another.

Been in this industry for over 20 years and am amazed sometimes that there's still plenty to learn.

Anyway, happy to be here. :thumbsup:

That green screw: you are supposed to wrap the sheath of the romex cable around it, and then wire nut the tail to the other sheath's of the other romex's that are run into the same box.

 

[Pharon]

But why not just wire nut all the grounds together? I still don't get why there's a screw in a non-metallic box. If it was metal, I get it - just doesn't seem to make sense for plastic.

 

[macmikeman]

But why not just wire nut all the grounds together? I still don't get why there's a screw in a non-metallic box. If it was metal, I get it - just doesn't seem to make sense for plastic.

Well, when they came out, I kinda thought the same thing myself.

 

[Pharon]

Sorry, I'm a little slow - just got your joke about the sheath from before... lol

 

[99cents]

It's attached to a metallic strap that goes to the screw hole for the wiring device. It is intended to ensure that the yoke of the wiring device is bonded.

Sorry guys, I gave up the secret, didn't I?

My bad.

 

[hardworkingstiff]

It's attached to a metallic strap that goes to the screw hole for the wiring device. It is intended to ensure that the yoke of the wiring device is bonded.

I would think the bond screw on the switch or receptacle would take care of that, I always wondered if it was in case someone used a metal blank plate.

 

[99cents]

You're right but the metal strap goes to the screw hole for the device. I think this discussion has been around the block here a few times already, though.

Good point about the metal plate...

I worded that wrong. It sounded like I was disagreeing with you, stiff, but I'm actually agreeing with you. Good thing I am escaping the office soon. My brain is turning to mush.

 

[erics37]

It's attached to a metallic strap that goes to the screw hole for the wiring device. It is intended to ensure that the yoke of the wiring device is bonded.

Sorry guys, I gave up the secret, didn't I?

My bad.

Not in USA

 

[HARRY304E]

Hi everyone! I'm a registered electrical engineer from Boston, MA, and I stumbled onto this site because I was trying to figure out why some PVC boxes have green ground screws in them.

My house is full of knob-and-tube wiring, so I may be asking some questions in the near future about how best to fish wiring from one place to another.

Been in this industry for over 20 years and am amazed sometimes that there's still plenty to learn.

Anyway, happy to be here. :thumbsup:

Welcome:thumbsup:

 

[papaotis]

OMG, it must not be a carlon blue!:laughing: