250.118 - using emt conduit as a ground
- Thread starter difowler1
- Start date
- Status
packersparky
Senior Member
- Location
- Wisconsin
- Occupation
- Inspector
To add to Roger's response, many studies have shown that a metallic raceway performs better at clearing a fault than a wire type equipment grounding conductor.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
We use EMT as an EGC all of the time unless someone is paying for a wire type EGC in the raceway.
peter d
Senior Member
- Location
- New England
:thumbsup:
I don't get the obsession with wire EGC's. I always encounter EMT installations done from the 1960's to the 1980's and it never had a separate ground wire. Now it does. :roll:
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Not weird at all. The size of EMT large enough for a given set of conductors has a lower impedance than the associated EGC size would.
MAC702
Senior Member
- Location
- Clark County, NV
It did to me, too, because all my apprenticeship years were for places that spec'd the wire EGC, so it was normal for me. Now, people pay me to just make it work, and I'm the one buying and pulling the wire, so....
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Seen many from the time period you mentioned with poorly supported raceway contributing to broken fittings resulting in loss of EGC, also seen loose set screws or compression nuts, but that is all workmanship issues more than anything IMO. Have seen poorly made up EGC's in cable wiring methods as well - open continuity is still open continuity.
I do a lot of grain storage bins and handling equipment. Generally all steel structures and equipment. I do run EGC's in flexible conduits or in any non metallic raceways (which is usually just underground raceways in these applications) but see running any wire EGC in most of said systems as pointless, the equipment/structures are very effective fault return path, and usually more effective than my raceways, so if a fitting didn't get tightened it doesn't really matter much from equipment grounding perspective.
Plus, dropping that one conductor when emt is used, helps somewhat for the added conductors we now have to add for MWBC's that we didn't used to have to install.
That is for us old dogs that always used MWBC's and now don't like tying individual circuit handles together.
JAP>
That is for us old dogs that always used MWBC's and now don't like tying individual circuit handles together.
JAP>
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
- Location
- New Jersey
- Occupation
- Journeyman Electrician
If the raceway is so good as an EGC why is there ever a need for redundant grounding? Needs to be extra good?
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I didn't write the rule, apparently it knows when it is in a health care facility and gets nervous or somethingIf the raceway is so good as an EGC why is there ever a need for redundant grounding? Needs to be extra good?
Haven't seen EMT used for any installations since I was doing my apprenticeship in the 1840s....and even then we had to run a separate earth (grounding) conductor...
Man..... you're OLD!!!!!!!
peter d
Senior Member
- Location
- New England
If the raceway is so good as an EGC why is there ever a need for redundant grounding? Needs to be extra good?
Pfft, not only do I run a ground on the inside, I run one on the outside as well.
Agree, if set screws are tight then your are good to go, but Ive come across installations [done by others] with duck tape used for couplings.
hmy:- Status