Mixed types of raceways and grounding / bonding?

Strahan

Senior Member
Location
Watsontown, PA
I've recently looked at a job where they want to expand operations and saw something that I'm not sure is legal. This is a commercial project small control panel for controlling pump motors and electric burners. Install consists of the motor branch circuits leaving the panel in non-metallic liquidtight for flexibility and then connecting to EMT. The liquidtight is about 3-4' in length before transferring to EMT. There are 3 - 3phase motor circuit run in this raceway and each motor run has its own dedicated EGC. The control panel is properly grounded to it's source and each motor circuit is properly grounded in the control panel. I'm having a problem with the EMT to liquidtight transformation. Even though the liquidtight is under 6' long shouldn't the EMT somehow be bonded to the panel???
 

ActionDave

Moderator
Staff member
Location
Durango, CO, 10 h 20 min without traffic from wing
Occupation
wire pulling grunt
Since the liquidtite is non-metalic it makes no matter at all if it is less or more than six feet.

You say "The control panel is properly grounded to it's source and each motor circuit is properly grounded in the control panel."

Where is the EMT not grounded/bonded?
 

Strahan

Senior Member
Location
Watsontown, PA
Since the liquidtite is non-metalic it makes no matter at all if it is less or more than six feet.

You say "The control panel is properly grounded to it's source and each motor circuit is properly grounded in the control panel."

Where is the EMT not grounded/bonded?
Maybe I'm trying to think too much, but motor circuit leaves control panel through flex, to EMT which is then branched off to each motor. What if a ground fault takes place in the EMT before the motor? The EMT is not effectively grounded at either end
 

Strahan

Senior Member
Location
Watsontown, PA
This keeps getting worse. What is it that you are looking at?
Well I'm thinking that this EMT needs bonded to the control panel by some means. Of course I don't know of an easy fix without un-hooking wires. The EMT is fastened to the wall behind the panel by strut. I'm not sure if they make something that would be legal to bond the strut to the panel therefore bonding the EMT? I'm sure the strut straps are not listed for the purpose. Open for any suggestions
 

ActionDave

Moderator
Staff member
Location
Durango, CO, 10 h 20 min without traffic from wing
Occupation
wire pulling grunt
Well I'm thinking that this EMT needs bonded to the control panel by some means.
I think so too.
Of course I don't know of an easy fix without un-hooking wires.
Me neither, but you are not giving many helpful details.
The EMT is fastened to the wall behind the panel by strut. I'm not sure if they make something that would be legal to bond the strut to the panel therefore bonding the EMT? I'm sure the strut straps are not listed for the purpose. Open for any suggestions
??? It all could be good or not.
 

Strahan

Senior Member
Location
Watsontown, PA
I think so too.
Me neither, but you are not giving many helpful details.
??? It all could be good or not.
What details are you looking for that I'm not providing? Power conductors for three motors leave the control panel along with an EGC for each circuit. Out of box through 1" non-metallic flex which couples to EMT which is fastened to uni-strut. Conduit extends up in ceiling into a TEE which has a cord and plug drop for 1st motor. Next, is a LB with same set up cord and plug. All motors have separate EGC's. I'm looking for a type of bonding clamp so I can run a bonding wire from it to the panel.
 

mgookin

Senior Member
Location
Fort Myers, FL
So you're saying the middle of the run is EMT which is not bonded at either end, right? Meaning it's not bonded at all?

From the start of the thread it was confusing because it appeared it was bonded at the equipment, but now that you mention these drops of cord & plug, it's clear (I think).
 

Strahan

Senior Member
Location
Watsontown, PA
So you're saying the middle of the run is EMT which is not bonded at either end, right? Meaning it's not bonded at all?

From the start of the thread it was confusing because it appeared it was bonded at the equipment, but now that you mention these drops of cord & plug, it's clear (I think).
Not bonded at either end. Sorry for the confusion. Any ideas?
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Well I'm thinking that this EMT needs bonded to the control panel by some means. Of course I don't know of an easy fix without un-hooking wires. The EMT is fastened to the wall behind the panel by strut. I'm not sure if they make something that would be legal to bond the strut to the panel therefore bonding the EMT? I'm sure the strut straps are not listed for the purpose. Open for any suggestions
There is no provision of the code that would let you use the conduit mounting system as the required bonding of the EMT.

A bonding jumper needs to be installed around the non-metallic flex at the supply end of the conduit.
 

Strahan

Senior Member
Location
Watsontown, PA
There is no provision of the code that would let you use the conduit mounting system as the required bonding of the EMT.

A bonding jumper needs to be installed around the non-metallic flex at the supply end of the conduit.
Ok. Flex is run to supply end cabinet. How do I accomplish bond to conduit? Is a bonding clamp around conduit ok?
 

Strahan

Senior Member
Location
Watsontown, PA
There is no provision of the code that would let you use the conduit mounting system as the required bonding of the EMT.

A bonding jumper needs to be installed around the non-metallic flex at the supply end of the conduit.
What I want to do is use a bonding/grounding clamp around the EMT and run a bonding wire to the cabinet. The bonding wire will run around the flex. I'm just having a rough time coming up with a clamp suitable for this purpose.
 

kwired

Electron manager
Location
NE Nebraska
What I want to do is use a bonding/grounding clamp around the EMT and run a bonding wire to the cabinet. The bonding wire will run around the flex. I'm just having a rough time coming up with a clamp suitable for this purpose.
same type of clamp used to bond water pipes will work just fine.
 

Strahan

Senior Member
Location
Watsontown, PA
same type of clamp used to bond water pipes will work just fine.
Thank you! I was trying to find something specifically rated for the EMT. I was being told by local electrical distributer that if its listed for "water pipe" then that's the only use. I kinda agreed with them although I know it is serving the same purpose. Just want it to be right.
 

kwired

Electron manager
Location
NE Nebraska
Thank you! I was trying to find something specifically rated for the EMT. I was being told by local electrical distributer that if its listed for "water pipe" then that's the only use. I kinda agreed with them although I know it is serving the same purpose. Just want it to be right.
I could be wrong but am guessing they are rated for any pipe, tubing, rod that is within the correct size range, direct burial may be an optional rating, but would be more likely for bronze or stainless then for aluminum or zinc clamps.
 

mgookin

Senior Member
Location
Fort Myers, FL
I could be wrong but am guessing they are rated for any pipe, tubing, rod that is within the correct size range, direct burial may be an optional rating, but would be more likely for bronze or stainless then for aluminum or zinc clamps.
I'd guess they are marketed towards potable water pipe because that's the primary market for the product.

The specific listing will likely clarify that it's for bonding metallic pipe.

Regardless, if that's the closest fit product you can come up with and you do it, then put an ohm meter on it and verify the objective is accomplished, I can't see how anyone can say you did it wrong.
 
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