250.118 - using emt conduit as a ground

kwired

Electron manager
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. :eek:hmy:
And also seen 1/2 FMC fittings used for 3/4 EMT. Works great when you ran 3/4 but didn't know how to enlarge a 1/2 KO, or if you needed a 90 degree connector:blink:
 

LarryFine

Master Electrician Electric Contractor Richmond VA
. . . Ive come across installations [done by others] with duck tape used for couplings. :eek:hmy:
I'm sure the duct tape was put on to facilitate using vacuum to pull in string to pull in a pull rope.
 

DBoone

Senior Member
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. :eek:hmy:

Always use aluminum foil duct tape, maintains continuity....good to go
 

Adamjamma

Senior Member
It comes down to installation... in UK and USA I don’t run into much rusted out emt, so the use of it for ground is fine. In Caribbean I run into a lot of rusted out emt with no continuity of ground... so in Caribbean I always add a ground conductor...
 

petersonra

Senior Member
It comes down to installation... in UK and USA I don’t run into much rusted out emt, so the use of it for ground is fine. In Caribbean I run into a lot of rusted out emt with no continuity of ground... so in Caribbean I always add a ground conductor...
It seems to me that if the EMT is rusting out it is not suitable to use it at all in that location.
 

kwired

Electron manager
Used to be it was used in concrete... now pvc conduit more common. But, emt is still allowed in concrete as I recall.
PVC preferred in slab on grade or in walls below grade. Above grade I don't think matters much most cases unless corrosive agents are involved in the general area.
 

hornetd

Senior Member
If the raceway is so good as an EGC why is there ever a need for redundant grounding? Needs to be extra good? :)
In rooftop applications it is specified to overcome the possibility; some would say likelihood; that the connections of the steel EMT will corrode open.
 

hornetd

Senior Member
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. :eek:hmy:
Are you having us on? I've seen a lot of duct tape used to render fittings concrete tight.
 

480sparky

Senior Member
In rooftop applications it is specified to overcome the possibility; some would say likelihood; that the connections of the steel EMT will corrode open.
Why would someone specify the need for a grounding conductor..... when they could specify a raceway fitting that won't corrode away?
 

hornetd

Senior Member
Project manager! Need I say more?

Project manager! Need I say more?

Why would someone specify the need for a grounding conductor..... when they could specify a raceway fitting that won't corrode away?
Because it's cheaper. Why Else? They specify compression couplings but many of those are not evan listed as rain-tight. And then for good measure they specify aluminum boxes to throw dissimilar metals into the mix. I've actually have seen one aluminum EMT job with all compatible fittings and boxes but that was on the roof of a a Biotechnology Laboratory.

But why am I complaining about this stuff when I have had an inspector say he preferred plastic boxes for their additional inside volume used with EMT in a Fire Alarm System. Before you ask they were not the ones with the bonding strap inside the box to bond all of the KOs to each other. That same inspector approved a Fire Pump Controller with no neutral conductor back to the Wye connected utility transformer. But I was just an Electrician on that job and the project manager thought that the foreman was a hero for all of the money he saved.
 

kwired

Electron manager
In rooftop applications it is specified to overcome the possibility; some would say likelihood; that the connections of the steel EMT will corrode open.
Design decision, not a code requirement. Just as much design decision as one could run stainless or brass conduit and probably have little or no corrosion troubles, but would definitely be more expensive.
 

kec

Member
Are you having us on? I've seen a lot of duct tape used to render fittings concrete tight.
No, I get using tape to facilitate helping vacuum or making fittings tight and have used this method but what I was saying is I came across duck tape used as the coupling only
 
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