Grounding LFMC

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ajks1

Member
Does the metal core in liquid tight flexible metal conduit need to be grounded for lengths greater that 6 feet?

[ May 02, 2003, 10:17 AM: Message edited by: ajks1 ]
 

jim dungar

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Staff member
Location
Wisconsin
Occupation
Retired Electrical Engineer - Power Systems
Re: Grounding LFMC

Yes - bu it does depend on what LFMC you are using. In some cases even a seperate ground may be required even for lengths less than 6 ft.

There are two general types of LFMC. One usually carries a JIC marking and the core is not listed as a ground conductor (i.e. Electri-Flex Liquatite type LT). The other is UL Listed and the core is an approved grounding conductor. The core often has a seperate copper ribbon wound into it (i.e. Electri-Flex Liquatite type LA).

The application sheet for Electri-Flex Liquatite type LA state "...Suitable as a grounding conductor when used for circuits rated up to 20A for the 3/8 & 1/2 inch grade sizes and 60A for the 3/4 through 1-1/4 inch trade sizes in lengths six feet or less per NEC Article 351-9..."
 

batch

Member
Location
Florida
Re: Grounding LFMC

Originally posted by ajks1:
Does the metal core in liquid tight flexible metal conduit need to be grounded for lengths greater that 6 feet?
It seems to me as if your question were regarding the grounding of the metal of the conduit and not its use as a ground.

Such as when leaving a non-metalic box and going equipment. If this is the case and you go into a metal enclosure which is grounded. Then the conduit would be grounded. If you go between to non-metalic boxes then you would need to use a grounding bushing on one end of the LT.

That is if I read your question correctly...
 

gwz2

Senior Member
Location
Indiana
Re: Grounding LFMC

Seems as though 250.86 Ex 2 is an 'out'.


For additional safety, do ground any metal object that may become energized to a grounding system as per 250.4.
 
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