Grounding LFMC conduit for non metallic boxes

[Khaledhn]

Good day ,

As per NEC 350.60 ,Where used to connect equipment where flexibility is required after installation, an equipment grounding conductor shall be installed. Is grounding of LFMC both ends required if it runs between two non-metallic enclosures ( GRP or Glass Reinforced Plastic) ? Is NEC 250.134 applicable in this situation ( isolated raceway) .

Note that LT connector is PVC coated . The system voltage is 24 Vdc , Load is 2.5 Amps and enclosures are mounted on steel structural which is already grounded .

 

[Adamjamma]

If I recal right, lfmc condit is required a bonding bushing, even for non metallic boxes, or you have to have a ground cable inside the conduit! Though some do both. These various cables in the box would all be connected to each other to keep the ground current as one item. If this was done inside the junction box, the junction box does not need a separate grounding wire... because the continuity of ground is maintained, the same as continuity of ground is maintained in a pvc system.

At least that is my 7nderstanding here in the UK, for the latest codes. Believe it same in the NEC.

 

[hbiss]

I have no idea what those connectors are that you used. LFMC (Sealtite) connectors are metallic and if you needed to bond the LFMC you would use a grounding or bonding bushing within the enclosure on all connectors and bond all together.

However, this is low voltage. I don't know what 24v@2.5a is in terms of whether it's Class 1 or CL3 or 2. YOU need to determine that from the power supply, I'm not going to do that for you, it should say right on it. If it says nothing then it is assumed to be Class 1. If it is Class 1 then, yes grounding is required as you need to use a Chapter 3 wiring method- same as power and light. However if it's CL3 or CL2 then no grounding is necessary.

-Hal

 

[peter d]

KSA = Kingdom of Saudi Arabia? If so, don't they follow the British Standard?

 

[Khaledhn]

With reference to NEC 2011 and above , 350.60 ; 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 . Therefore ,it is not necessarily to provide equipment grounding conductor for the LFMC since the equipment are fixed (GRP boxes).

 

[Adamjamma]

If so, then it would be all the pipes in bonded with bushing inside, to ground screw inside if one is provided, or to proper joint.. wire nut, clamp, etc. so as to continue the ground. I don’t have the BS7671 to quote the exact code but it is not in my onsite guide to give it either... just remember the videos on it... because the conduits used have metal in them, you can use them to continue the grounding or earthing of the installation.
The idea is to give as many paths for lightening to get to earth and avoid destroying the power systems.

 

[tkb]

If I recal right, lfmc condit is required a bonding bushing, even for non metallic boxes, or you have to have a ground cable inside the conduit! Though some do both. These various cables in the box would all be connected to each other to keep the ground current as one item. If this was done inside the junction box, the junction box does not need a separate grounding wire... because the continuity of ground is maintained, the same as continuity of ground is maintained in a pvc system.

At least that is my 7nderstanding here in the UK, for the latest codes. Believe it same in the NEC.

If a metallic raceway is connected to a nonmetallic enclosure, bonding bushings are required and must be connected to the equipment grounding conductor.

I guess a handyman wouldn’t know that, but an electrician would.

 

[Carultch]

If a metallic raceway is connected to a nonmetallic enclosure, bonding bushings are required and must be connected to the equipment grounding conductor.

I guess a handyman wouldn’t know that, but an electrician would.

Correct me if I am wrong, but it is my understanding that if the conduit is properly bonded on the other end, and you are using a wire EGC, that you don't need a bonding bushing on both ends. This assumes that the conduit is for a general purpose that is either a feeder or branch circuit, as opposed to a service conduit, and contains no GEC's. Said conduit could be "properly bonded on the other end", either with a standard metal locknut on a grounded metal enclosure (either with no ring KOs remaining, or a voltage/product where it is OK to rely on ring KO's), or with a bonding bushing/jumper.

I don't read anywhere in the NEC that conduit needs to be bonded on both ends, if not used as the EGC itself.

 

[tkb]

Correct me if I am wrong, but it is my understanding that if the conduit is properly bonded on the other end, and you are using a wire EGC, that you don't need a bonding bushing on both ends. This assumes that the conduit is for a general purpose that is either a feeder or branch circuit, as opposed to a service conduit, and contains no GEC's. Said conduit could be "properly bonded on the other end", either with a standard metal locknut on a grounded metal enclosure (either with no ring KOs remaining, or a voltage/product where it is OK to rely on ring KO's), or with a bonding bushing/jumper.

I don't read anywhere in the NEC that conduit needs to be bonded on both ends, if not used as the EGC itself.

Please read 314.3 Execption 1.

 

[Adamjamma]

Well, because the metallic conduit makes an alternate ground path if a short happens within it, or can become energized by the circuits within it, it is required that you use proper bonding at both ends of it. If it is the type that contains an insulating cover of pvc, etc... then the metal should be bonded to the metal panel, if entering such, by a bonding bushing. If not a metal panel, then use of an internal bonding method or jumpers from bonding bushing to a grounding bar within the panel is required.

the instructor here was like, use an appropriate wago block to attach the grounding spurs to... the main thing is continuity of the CPC.

Again, not sure of code section as I have not yet bought my big code book, and the on-site guide is just a guide..

but, it is a common sense and it is for bonding reasons to make sure shorts have all the paths possible to keep from hurting people and going to the ground system... while allowing safety devices to work.

 

[tkb]

Well, because the metallic conduit makes an alternate ground path if a short happens within it, or can become energized by the circuits within it, it is required that you use proper bonding at both ends of it. If it is the type that contains an insulating cover of pvc, etc... then the metal should be bonded to the metal panel, if entering such, by a bonding bushing. If not a metal panel, then use of an internal bonding method or jumpers from bonding bushing to a grounding bar within the panel is required.

the instructor here was like, use an appropriate wago block to attach the grounding spurs to... the main thing is continuity of the CPC.

Again, not sure of code section as I have not yet bought my big code book, and the on-site guide is just a guide..

but, it is a common sense and it is for bonding reasons to make sure shorts have all the paths possible to keep from hurting people and going to the ground system... while allowing safety devices to work.

Handyman, you should read the code before you make comments that don’t make sense.