There's No Grounding Conductor in Disconnect Switch and Circuit Breaker Enclosure

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DrSparks

The Everlasting Know-it-all!
Location
Madison, WI, USA
Occupation
Master Electrician and General Contractor
I dont at all agree that changes in the NEC and the modern proclivity towards running wire EGC's are based on real world problems. Look at all the absurd crap in article 250 that has been there for half a century or more, most of the recent GFCI expansions, AFCI's, the surge protector requirement, no more MLO's, handle ties on MWBC's.....the list goes on. Pretty much no data or history of problems for this stuff.
So house fires and electrocutions are not real world occurrences?

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DrSparks

The Everlasting Know-it-all!
Location
Madison, WI, USA
Occupation
Master Electrician and General Contractor
Can the utility company just shut it off remotely?
Not always so easy or fast. Sometimes you have to pull a fuse on the pole. All depends. Do you think q firefighter is going to wait for a POCO truck to show up? They are not emergency response vehicles. At least I've never pulled over for a bucket truck... Wait was I supposed to??

EDIT: most substations have remote control disconnects but they won't kill a substation to shut off one building.



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paulengr

Senior Member
I agree if it's wrench tight threaded rigid conduit. I don't consider EMT with setscrew connectors a viable EGC. Just from my own experience in years of factory work.

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The set screw pushes the EMT tightly against the other side.
 

DrSparks

The Everlasting Know-it-all!
Location
Madison, WI, USA
Occupation
Master Electrician and General Contractor
Nope. Complete scam.
Look, I get your point, I really do. There's a lot of bureaucracy and corporate cronyism in... well, just about everything... But I personally know someone, a good friend, actually, who was electrocuted on the job. It wasn't because of a code violation or no GFCI, but when you have it happen to someone you know, it becomes personal. I consider all safety improvements, no matter how marginal they are to be good. If it saves one person's life out of every human on earth, then it was worth it. Just my opinion I suppose.

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paulengr

Senior Member
You are all wet on an EGC.




Summary: Both EMT and GRC impedance is vastly less than a copper EGC. The resistance of steel is higher but it has the advantage of vastly more circular mills which easily overcomes the higher specific resistance.
 

DrSparks

The Everlasting Know-it-all!
Location
Madison, WI, USA
Occupation
Master Electrician and General Contractor
The set screw pushes the EMT tightly against the other side.
I get that, but set screw couplings, especially the cast zinc ones, are subject to cracking from over torquing and heavy vibrations and temperature extremes can cause them to become loose.

Yeah you're going to say that it's all about how you install it, but I'm pretty sure most electricians don't use torque wrenches to fasten set screw connectors.

Stranded copper wire on compression crimp terminals bolted to a busbar with lock washers is how I roll.

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DrSparks

The Everlasting Know-it-all!
Location
Madison, WI, USA
Occupation
Master Electrician and General Contractor
That just doesn't make sense though. The cost vs benefit has to evaluated. Sounds cruel but it's the truth.
Yeah, I should mention that I was really only referring to feeders. Not like 20 amp receptacle circuits and such.

No, you're right about cost vs benefit, but there were other benefits to our decision to go all crimp terminations. We had a big problem with termination failure in disconnects requiring us to have to do ridiculous PM operations in addition to cleaning the fuse holders. We redid all our discos and never had a problem again.

Also, keep in mind that having a conductor EGC in addition to the conduit mitigates the amount of fault current passing through the conduit. Arcing can occur on loose couplings and connectors in high fault current situations. Especially at 480+

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I get that, but set screw couplings, especially the cast zinc ones, are subject to cracking from over torquing and heavy vibrations and temperature extremes can cause them to become loose.

Yeah you're going to say that it's all about how you install it, but I'm pretty sure most electricians don't use torque wrenches to fasten set screw connectors.

Stranded copper wire on compression crimp terminals bolted to a busbar with lock washers is how I roll.

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I honestly have never see the cracking, pulling out, or loosening of EMT fittings you and other people attest happens. Where is all the vibration coming from? You build carnival rides or something?

I like crimped and bolted connections too. But skip the lock washers, they are a scam - for real, they have done tests and they actually increase the propensity for loosening.
 

DrSparks

The Everlasting Know-it-all!
Location
Madison, WI, USA
Occupation
Master Electrician and General Contractor
I honestly have never see the cracking, pulling out, or loosening of EMT fittings you and other people attest happens. Where is all the vibration coming from? You build carnival rides or something?

I like crimped and bolted connections too. But skip the lock washers, they are a scam - for real, they have done tests and they actually increase the propensity for loosening.
Actually the nuts we use have the swivel lock washer built in. They work really well.

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hillbilly1

Senior Member
Location
Atlanta,Ga
Occupation
Field coordinator/ technical support
I get that, but set screw couplings, especially the cast zinc ones, are subject to cracking from over torquing and heavy vibrations and temperature extremes can cause them to become loose.

Yeah you're going to say that it's all about how you install it, but I'm pretty sure most electricians don't use torque wrenches to fasten set screw connectors.

Stranded copper wire on compression crimp terminals bolted to a busbar with lock washers is how I roll.

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I think it is more loose locknuts than set screws. That goes back to the “properly installed”
 

Natfuelbilll

Senior Member
Because the Cult of the Green Wire has most of the American electrical industry in it's clutches. A properly installed metal raceway is a better equipment ground than any size wire you could stuff in it.
Until racecar Robby smashes a die-cast condulet to smitherines with the fork truck. Then you have NO EGC.
 
Until racecar Robby smashes a die-cast condulet to smitherines with the fork truck. Then you have NO EGC.
What if the wire EGC isn't terminated correctly, what if I get hit by a bus tomorrow, what if someone sawzalls thru the conduit, what if a plane crashes into the building, what if I get cancer, what if the flux capacitor didn't get invented, what if there is no MBJ installed, what if the company goes bankrupt, what if I slip on the ice and crack my head open, what if no one fixes anything after race car Robbie crashes the forklift thru the wall and no one calls the coroner and the corpse just rots on the forklift.......
 

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min without traffic from wing
Occupation
Licensed Electrician
Until racecar Robby smashes a die-cast condulet to smitherines with the fork truck. Then you have NO EGC.
First, if electrical work is being damaged by forklifts then the something needs to be done about that beyond just putting a green wire in the conduit. Second, if you manage to get a piece of conduit isolated from any fault clearing path and it becomes energized then the extra green wire isn't going to clear the fault.
 
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