FMC to EMT Transition

[jtee1249]

Local code requires residential EMT everywhere, but allows FMC in "fishing" applications. Trying to fish down ~7-8' gypsum wall with FMC to basement where it will connect to 1900 box that then goes to EMT all the way to panel. FMC is longer than 6' so it requires a separate EGC, does this EGC have to go all the way to the panel or can it end at the box and the EMT serves as the EGC to the panel? Tried looking in NEC book and google but it's kind of a hard one to search for.

EGC-wire------->?<------------>
outlet->FMC->box->EMT->panel

Thanks

 

[don_resqcapt19]

Local code requires residential EMT everywhere, but allows FMC in "fishing" applications. Trying to fish down ~7-8' gypsum wall with FMC to basement where it will connect to 1900 box that then goes to EMT all the way to panel. FMC is longer than 6' so it requires a separate EGC, does this EGC have to go all the way to the panel or can it end at the box and the EMT serves as the EGC to the panel? Tried looking in NEC book and google but it's kind of a hard one to search for.

EGC-wire------->?<------------>
outlet->FMC->box->EMT->panel

Thanks

First, if you are in Chicago, you really have to look to the Chicago Electrical Code. The current version of that code is the 2017 NEC with about 150 pages of amendments.
Lacking a specific rule in the Chicago code that says otherwise, the EGC for the FMC can originate at the transition box as the EMT is suitable for use as an EGC.

 

[jtee1249]

I have looked in Chicago amended 2017 NEC and do not see any amendments in the Article on grounding/bonding or the article on FMC in reference to this situation. So I think I am okay.

Thank you for your help!

 

[Carultch]

Bridgeport makes transition couplings to allow connecting EMT directly to FMC, without enclosure terminations.

Coupling, Combination, Zinc Die Cast, Flex Size 1/2 Inch

Used to join EMT to flexible metal conduit. 281-DC is squeeze type for flexible metal conduit. Set screw type for EMT end.

www.bptfittings.com

In the event that you need a separate EGC for a specific conduit type, it is only in the section of raceway that is that specific type, that necessarily requires an EGC. So if you terminate FMC at a box on both ends, and then transition to EMT, the separate EGC is only required to travel between the boxes in the FMC, and the EMT can take care of carrying the ground path the rest of the way.

 

[jtee1249]

Bridgeport makes transition couplings to allow connecting EMT directly to FMC, without enclosure terminations.

Coupling, Combination, Zinc Die Cast, Flex Size 1/2 Inch

Used to join EMT to flexible metal conduit. 281-DC is squeeze type for flexible metal conduit. Set screw type for EMT end.

www.bptfittings.com

In the event that you need a separate EGC for a specific conduit type, it is only in the section of raceway that is that specific type, that necessarily requires an EGC. So if you terminate FMC at a box on both ends, and then transition to EMT, the separate EGC is only required to travel between the boxes in the FMC, and the EMT can take care of carrying the ground path the rest of the way.

Don't think this would work unless I ran the EGC through the entire run

 

[infinity]

Only the raceway that does not qualify as an EGC (the FMC longer than 6') requires the wire type EGC. The EMT would not require a wire type EGC so the question is how do you transition from one wiring method to the other with only a wire type egc in the FMC. As suggested a box would be needed.

 

[garbo]

Local code requires residential EMT everywhere, but allows FMC in "fishing" applications. Trying to fish down ~7-8' gypsum wall with FMC to basement where it will connect to 1900 box that then goes to EMT all the way to panel. FMC is longer than 6' so it requires a separate EGC, does this EGC have to go all the way to the panel or can it end at the box and the EMT serves as the EGC to the panel? Tried looking in NEC book and google but it's kind of a hard one to search for.

EGC-wire------->?<------------>
outlet->FMC->box->EMT->panel

In my area using the EMT to ground a device is acceptable but I would not recomend it. Too many times in my 50 year carrer I have came across EMT that was pulled out of a coupling thus losing the important ground. I had a lazy cut every corner cheif electrican who never pulled a ground wire for any 480 volt circuits he ran thru EMT. Somebody reported a EMT conduit that got pulled out of a connector that he installed a year earlier. He gripped the think it was 1.25" EMT with power on and came very close to getting electrocuted. One or two of the wires were nicked facing the wall where is was not visible. First he received a huge shock and wires sparked for several seconds due to he was too lazy to provide over current protection on transformer secondary that he installed. After that he always ran a ground wire. At the large hospital that I retired from I had a several year battle with a senior know it all electrician. He insisted that we use use greenfield to fish 120 volt power to patient room receptacles that walls were filled with thick dense itchy wool insulation. I always used hospital grade Type AC cable that had an insulated ground wire along with bare thin aluminum wire. Was taught that the ground wire is the most critical in any circuit so we were taught to always connect ground wire first and was the last to be removed.