ECN Forum Forums General Topics of the Trade General Discussion Area grounding metal boxes,per 250.148

Thank you guys for the input, I have always wondered about whether to attach an egc to each metal box,or not.

DougW: I order exclusively Cooper Crouse-Hinds j-boxes and always purchase the raised threaded ground screw mount.

MJ: I, too, use an EGC in each metal box.

If the circuit conductors run through a metal box without splice, then the box does not have to have the e-ground wire attached to it, does it?
I would attach it anyway.

I usually don't pigtail to the box. Normally I'll strip a section of the incoming (upstream) power's EGC, (makes it easier to identify which is the "hot" side later) wrap it around the ground screw or through the lug (lay-in lugs are great for this), and splice the other grounds to the end of that conductor.

Wow! you guys are all together on this one. I'v been in the trade since '79 and I don't think I've ever grounded a box in a pipe run unless it was specked. If I'm wrong point me in the right direction.

If you have a metal P-Ring or a raised cover, Doesn't that automaticly bond the box?

Does the NEC say you have to have a pigtail to the box eventhough the P-Ring and the Raised cover plate is metal and the receptacle has a good mechanical connection to the ring then to the box?

Not that pigtailing is a big job, just want to know for my own info.BTW i am with Curt i always pull grounding through all my piping.

Edward

[This message has been edited by Edward (edited 04-20-2004).]

2002 NEC 250.148

Always follow the specifications and plans.

I recommend the installation of the additional EGC. It is another way of being sure that the path will be there when needed, especially when the fitting vibrates loose.

That was an issue discussed at the proposal and comment meetings for the new code.

Ryan, please tell them about the EGC raceway fill requirements in Chapter 9, and the adjustment factor in Article 310.

How close are you to St. George, UTAH?

Hi Joe! I'm about 300 miles North of St. George. St. George is just over the border from Arizona. If your headed that way, I'm sure you'll enjoy the climate this time of year, and if you have time, take a minute to enjoy some of the scenary outside of town. Drop me an e-mail when your around and I'll see if I can't make it down there.

As far as raceway fill goes, the EGC must be counted because it consumes some of the volume of the conduit. When I think about raceway fill, I am thinking that we are trying to protect the conductors from damage while in the process of installing them. With that in mind, the EGC counts. Note 1 to the table tells us that the raceway fill section is dependant upon a moderate number of bends and length of pull. That is why you can load a nipple with more wire...your not pulling the conductors, but instead you are pushing them...much less probablity for damge.

As far as the ampacity adjustments go, the EGC need not be counted as a current carrying condutor because, under non-fault conditions, it does not carry current. The only issue that I have is that, in my opinion, if you have to increase the size of phase conductors and grounded conductors becasue of ampacity adjustment, you must also increase the size of the EGC, as per 250.122(B).

Thanks Ryan:

Good explanation. I asked about UTAH because my wife is stranded there now because her Uncle who is 96 years old is in intensive care.

I've got 2 switchs in a double gang raised cover going on a surface mounted 4 sq. The switches don't have the grounding spring. I pigtail the box and one of the switches, do I have to pigtail the other switch. BTW I did but just curious