Grounding Low Voltage can?

[hagak]

So I have installed a Elk 28" can with a outlet mounted on the bottom. The outlets ground is tied to the metal Jbox the outlet is in and the metal Jbox is secured to the metal Elk can. Is this sufficient grounding of the Elk can? Note the Elk can has no ground screw mounted on it.

Second box is a Leviton can that I mounted a similar outlet to the bottom. However the Leviton can actually has a ground screw on it but not in a great location for tieing back to inside the outlet Jbox. Do I still need to tie a wire somehow to that poorly located ground screw or is my ground Jbox sufficient?

Note in both cases I did confirm that the can has low resistance to the AC ground via a multimeter.

 

[Del91574]

Yes and no.

Elk does not recommend grounding the M1 panels. The enclosure can be grounded, however, but a bonding jumper is needed from the electrical ground to the enclosure. They do come with a ground screw, however I can't remember where it lands off the top of my head.

Physical connection is not sufficient for bonding the ground between the EG and enclosure, a bonding jumper is needed and paint needs to be scraped off.

If the enclosures are piped together using EMT, then a bonding jumper would not be necessary.

 

[hagak]

Ok so I need to run a ground on the leviton but not the Elk? Seems odd they would be different.


Do I run the ground back to my main breaker box ground or is tieing the panel to the ground on the outlet sufficient?

 

[Del91574]

2 different things, re-read carefully.

I said Elk's panel (M1) is not supposed to be grounded. The enclosure should be bonded to the EG, it comes with a spiffy green screw to do such. I can't remember where it's landed off the top of my head.

The EG is fine for just that, an EG. If you have surge protection installed, it should be a dedicated ground bonded to the ground rod or as close as practical.

 

[hagak]

Ok. So not sure if I understand the where I should be bonding the enclosure to ground. Do I bond it to the nearest EG which would be the wiring going to the outlet in the enclosure or back to the ground rod?

Not sure why it would need to go back to the ground rod unless wire gauge of the outlet is not considered sufficient.

 

[Del91574]

If you are grounding for the purpose of surge protection, the ground needs to go to the ground rod. For the purpose of EG, you can bond to the EG.

Irregardless, the bonding jumper needs to be equivalent to 14 AWG, either bare copper, green, green/yellow tracer, or identified using green on the exposed portion of the insulation.

 

[Digger]

If you are grounding for the purpose of surge protection, the ground needs to go to the ground rod. For the purpose of EG, you can bond to the EG.

Irregardless, the bonding jumper needs to be equivalent to 14 AWG, either bare copper, green, green/yellow tracer, or identified using green on the exposed portion of the insulation.

You may want to double check the NEC. I believe that the bonding conductor must be equal to or greater than the branch circuit conductors (i.e. a 15 amp branch circuit would be min. 14 awg bonding but a 20 amp branch circuit would be min. 12 awg bonding).

 

[hagak]

Ok cool. Not grounding for surge. And the circuit is 12ga. So will ground with bare 12ga

 

[Del91574]

If you're running a fire alarm, should be a dedicated circuit, 15A, and using 12 AWG is a violation for the branch circuit wiring, not for a ground.

 

[tmbrown97]

I'm definitely NOT an electrician and have little knowledge of the NEC, but I could've sworn I read that all circuits are now 12AWG regardless... I wish I knew where I read that, but it was when researching running all my outdoor circuits and spa panel; I did a lot of digging then all about general electric wiring.

I haven't checked my smoke wiring specifically, but I haven't come across any 14AWG in anything I've touched yet in this pretty new house, which includes every light switch and a few outlets.

 

[InspiredTim]

If the junction box is screwed to to the can than an earth wire from the outlet to the mounting screw will be
enough. The earth wire should be the same gauge as the earth wire feeding the outlet. The earth screw on the can is a pre-made mounting location that guarantees bare metal contact with the can. Make sure you use a lug on the end of the earth wire to guarantee the wire doesn't come loose. Unless you are installing a lightning rod on your roof there is no need to run back to the earth rod. Just make sure that the earth is actually earthed than the rest should be fine.


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[video321]

If you're running a fire alarm, should be a dedicated circuit, 15A, and using 12 AWG is a violation for the branch circuit wiring, not for a ground.

DEL, what are you refering to? Code for a fire alarm or NEC?

 

[Digger]

If you're running a fire alarm, should be a dedicated circuit, 15A, and using 12 AWG is a violation for the branch circuit wiring, not for a ground.

Running a dedicated 20 A circuit for a Fire Alarm is not permitted? I think you may want to reread a little of the code. I dont have a copy of the NEC at home but I did check few UL Standards which do state the ground/bonding wire must be equal or greater than the branch circuits conductors i.e. if you are bonding dead metal (a FACP door) you can use 12 awg even on a 15 A branch circuit.

Almost every install I have ever worked on for FACP it has been dedicated 20 A branch circit but I think I do remember a few 15 A that were retrofits and the building owner did not feel it was necessary to rerun a 20 A circuit and it meets code so why not.

 

[hagak]

If you're running a fire alarm, should be a dedicated circuit, 15A, and using 12 AWG is a violation for the branch circuit wiring, not for a ground.

The elk can is on a dedicated 15a circuit.

The leviton that is for multimedia/network outlet is a branch off of a 20a circuit.