Debate on over Flex as Grounding Conductor

[roger]

d. Where used to connect equipment where flexibility is necessary after installation.

John, "d" actually says

d. Where used to connect equipment where flexibility is necessary after installation, an equipment grounding conductor shall be installed.

We have already established the fact that the FMC was not used for flexibility after installation so "d" is not in the equation, and in any case, 517.13(B) has already required the insulated EGC.

The installation is fine.

Roger

 

[brother]

John, what requirements are not being met? The flex is no longer than 6' with fittings listed for grounding and being protected by no more than a 20 amp OCPD is basically all that is needed, IOW's all of 250.118(5) is satisfied.

Roger

I think John needs to read the post more carefully next time. by the way, what does IOW stand for??

 

[brother]

John, "d" actually says We have already established the fact that the FMC was not used for flexibility after installation so "d" is not in the equation, and in any case, 517.13(B) has already required the insulated EGC.

The installation is fine.

Roger

I think a Code proposal is needed for the language in 250.118 (5)d. to further clear it up. It appears they did in 2008 NEC 348.60 a little bit. 348.60 says : "Where flexibility is NOT required after installation, FMC shall be permitted to be used as an egc" so one would think normally fmc would NOT be a egc.

in 250.118(5)d. says "Where used to connect equipment where flexibility is necessary after installation, an egc shall be installed".

The way the language is written here and can be interpeted if you did not go to 348.60 250.118 (5)(d) still has the fmc itself listed as an egc even when flexibility is needed 'after installation'. I do not believe this was in the intent of CMP, and it should reference 348.60 here in my opinion. what do you think??

 

[infinity]

I think a Code proposal is needed for the language in 250.118 (5)d. to further clear it up. It appears they did in 2008 NEC 348.60 a little bit. 348.60 says : "Where flexibility is NOT required after installation, FMC shall be permitted to be used as an egc" so one would think normally fmc would NOT be a egc.

in 250.118(5)d. says "Where used to connect equipment where flexibility is necessary after installation, an egc shall be installed".

The way the language is written here and can be interpeted if you did not go to 348.60 250.118 (5)(d) still has the fmc itself listed as an egc even when flexibility is needed 'after installation'. I do not believe this was in the intent of CMP, and it should reference 348.60 here in my opinion. what do you think??

I'm not sure if what you're saying would actually change anything. As Roger stated the way it is currently written the installation is fine.

 

[roger]

by the way, what does IOW stand for??

In Other Words.

Go here for more

Roger

 

[brother]

I'm not sure if what you're saying would actually change anything. As Roger stated the way it is currently written the installation is fine.

I know the installation is fine, but look at the language again in 250.118, it should reverence 348.60 if 250.118 intended for the fmc to NOT qualify as an egc when the flexibility is required after installation.

They still have it under that 250.118 section, so dealing with the english language and proper context, the NEC needs improvement in this area.

 

[Smart $]

I know the installation is fine, but look at the language again in 250.118, it should reverence 348.60 if 250.118 intended for the fmc to NOT qualify as an egc when the flexibility is required after installation.

They still have it under that 250.118 section, so dealing with the english language and proper context, the NEC needs improvement in this area.

I agree.

250.118(5)(d) does not say the fmc is not or no longer an egc under this stipulation. It even depends on what logic is used to interpret it. It says an equipment grounding conductor shall be installed. Therefore, one flavor of logic could say that's what the fmc is (i.e. using inclusive rather than exclusive logic). The general statement of 250.118 suggests inclusive logic because it states, "The equipment grounding conductor... shall be one or more or a combination of the following:"

With the preceding train of thought, the stipulation should read "an additional equipment grounding conductor shall be installed" if the intent were to install an additional equipment grounding conductor.

To clean the wording up, perhaps 250.118(5)(d) should read either:

Inclusive logic ? d. If used to connect equipment where flexibility is necessary to minimize the transmission of vibration from equipment or to provide flexibility for equipment that requires movement after installation, an additional equipment grounding conductor shall be installed.​

...or...

Exclusive logic ? d. Not used to connect equipment where flexibility is necessary to minimize the transmission of vibration from equipment or to provide flexibility for equipment that requires movement after installation.​

Note italicized text is a 2011 proposal.

 

[brother]

I agree.

250.118(5)(d) does not say the fmc is not or no longer an egc under this stipulation. It even depends on what logic is used to interpret it. It says an equipment grounding conductor shall be installed. Therefore, one flavor of logic could say that's what the fmc is (i.e. using inclusive rather than exclusive logic). The general statement of 250.118 suggests inclusive logic because it states, "The equipment grounding conductor... shall be one or more or a combination of the following:"

With the preceding train of thought, the stipulation should read "an additional equipment grounding conductor shall be installed" if the intent were to install an additional equipment grounding conductor.

To clean the wording up, perhaps 250.118(5)(d) should read either:

Inclusive logic ? d. If used to connect equipment where flexibility is necessary to minimize the transmission of vibration from equipment or to provide flexibility for equipment that requires movement after installation, an additional equipment grounding conductor shall be installed.​

...or...

Exclusive logic ? d. Not used to connect equipment where flexibility is necessary to minimize the transmission of vibration from equipment or to provide flexibility for equipment that requires movement after installation.​

Note italicized text is a 2011 proposal.

So is it safe to assume someone has already 'proposed a change' int he language in this section?? Would that be you Smart$??

 

[cowboyjwc]

I think John needs to read the post more carefully next time. by the way, what does IOW stand for??

And the same goes for you. I already said that we accecpt flex in med centers because it has a listing, but I know that all areas do not accept it. You already had to install an insulated grounding condutor per 517. (5) Listd flexible metal conduit meeting all the following conditions, not 3 of the four so he's not using it to connect equipmet where flexibility is necessary after installation.

Of course now I'm just picking the fly poop out of the pepper.

 

[brother]

And the same goes for you. I already said that we accecpt flex in med centers because it has a listing, but I know that all areas do not accept it. You already had to install an insulated grounding condutor per 517. (5) Listd flexible metal conduit meeting all the following conditions, not 3 of the four so he's not using it to connect equipmet where flexibility is necessary after installation.

Of course now I'm just picking the fly poop out of the pepper.

I never said you never accepted flex in med centers, I believe that was someone else.

I fail to your train of thought on the latter part of your comment. Especially the part

"You already had to install an insulated grounding condutor per 517. (5)" yes I did, and so therefore it meets the requirements of redundant grounding.

 

[roger]

but I know that all areas do not accept it.

John, what are they using to justify not accepting it? Do they have an amendment that supports their rejecting it?

Roger

 

[brother]

John, what are they using to justify not accepting it? Do they have an amendment that supports their rejecting it?

Roger

Probably their 'opinions' and 'handbook narritives'. Mr 'I want' Inspector or Mr 'I would like to see' Inspector.

 

[Smart $]

So is it safe to assume someone has already 'proposed a change' int he language in this section?? Would that be you Smart$??

Not I.

Don't know if anyone else has regarding the topic of our discussion. The proposed change as italacized above is the only change in the 20111 ROP Draft to the referenced section... and rejected proposals are not shown in the Draft.

 

[bwolf]

Here in Michigan our 2008 Part 8 Rules have ammended 250.118 and removed FMC and LFMC. 348.60 has also been changed.

250.118. Types of equipment grounding conductors. The equipment grounding conductor run with or enclosing the circuit conductors shall be 1 or more or a combination of the following:
(1) A copper, aluminum, or copper-clad aluminum conductor. This conductor shall be solid or stranded; insulated, covered, or bare; and, in the form of a wire or a busbar of any shape.
(2) Rigid metal conduit.
(3) Intermediate metal conduit.
(4) Electrical metallic tubing.
(5) Flexible metallic tubing where the tubing is terminated in listed fittings and meeting both of the following conditions:
(a) The circuit conductors contained in the tubing are protected by overcurrent devices rated at 20 amperes or less.
(b) The length of flexible metallic tubing in the ground return path does not exceed 1.8m (6 feet).
(6) Armor of type AC cable as provided in section 320.108 of the code.
(7) The copper sheath of mineral-insulated, metal-sheathed cable.
(8) Type MC cable where listed and identified for grounding in accordance with both of the following: (a) The combined metallic sheath and grounding conductor of interlocked metal tape-type MC cable.
(b) The metallic sheath or the combined metallic sheath and grounding conductors of the smooth or corrugated tube type MC cable.
(9) Cable trays as permitted by sections 392.3(c) and 392.7 of the code.
(10) Cablebus framework as permitted by section 370.3 of the code.
(11) Other listed electrically continuous metal raceways and listed auxiliary gutters.
(12) Surface metal raceways listed for grounding.
R 408.30869


348.60. An equipment grounding conductor or equipment bonding jumpers shall be installed. Equipment grounding conductors shall be installed in accordance with section 250.134(B) of the code. Equipment bonding jumpers shall be installed in accordance with section 250.102 of the code.
R 408.30867

 

[brother]

Here in Michigan our 2008 Part 8 Rules have ammended 250.118 and removed FMC and LFMC. 348.60 has also been changed.

250.118. Types of equipment grounding conductors. The equipment grounding conductor run with or enclosing the circuit conductors shall be 1 or more or a combination of the following:
(1) A copper, aluminum, or copper-clad aluminum conductor. This conductor shall be solid or stranded; insulated, covered, or bare; and, in the form of a wire or a busbar of any shape.
(2) Rigid metal conduit.
(3) Intermediate metal conduit.
(4) Electrical metallic tubing.
(5) Flexible metallic tubing where the tubing is terminated in listed fittings and meeting both of the following conditions:
(a) The circuit conductors contained in the tubing are protected by overcurrent devices rated at 20 amperes or less.
(b) The length of flexible metallic tubing in the ground return path does not exceed 1.8m (6 feet).
(6) Armor of type AC cable as provided in section 320.108 of the code.
(7) The copper sheath of mineral-insulated, metal-sheathed cable.
(8) Type MC cable where listed and identified for grounding in accordance with both of the following: (a) The combined metallic sheath and grounding conductor of interlocked metal tape-type MC cable.
(b) The metallic sheath or the combined metallic sheath and grounding conductors of the smooth or corrugated tube type MC cable.
(9) Cable trays as permitted by sections 392.3(c) and 392.7 of the code.
(10) Cablebus framework as permitted by section 370.3 of the code.
(11) Other listed electrically continuous metal raceways and listed auxiliary gutters.
(12) Surface metal raceways listed for grounding.
R 408.30869


348.60. An equipment grounding conductor or equipment bonding jumpers shall be installed. Equipment grounding conductors shall be installed in accordance with section 250.134(B) of the code. Equipment bonding jumpers shall be installed in accordance with section 250.102 of the code.
R 408.30867

Thats interesting. Well our area has no ammendment forbidding FMC as a egc.

 

[bwolf]

If there are no local amendments prohibiting FMC in hospitals or being used as an egc, I think the installation is compliant.

All the requirements of 250.118(5)a. b. c. d. have been met and the added insulated egc meets 517.13.

 

[cowboyjwc]

John, what are they using to justify not accepting it? Do they have an amendment that supports their rejecting it?

Roger

Once again, I did not say that we don't accept it, I said that there are some areas that may not.

Beverly Hills and the City of Burbank don't allow NMC, why I don't know, and yes they have an amendment.

 

[cowboyjwc]

Probably their 'opinions' and 'handbook narritives'. Mr 'I want' Inspector or Mr 'I would like to see' Inspector.

When you know me better, I'll let you make that up to me.