Should I run a separate ground wire when using metal conduit/boxes?

[bucktruck]

Title says it all. I'm starting to do the electrical in my garage, and have decided to go with external metal boxes and conduit mounted directly to my painted OSB walls. I like the way external wiring looks, and I like that it will give me some flexibility in the future in case I need to make changes.

The plan is to have one circuit for lights, one for 110V outlets, one for heating and A/C, a 220V circuit for the milling machine/lathe (and possibly MIG,) and a 220V circuit for the air compressor.

So, separate ground wire for each, or will the metal conduit suffice? My searches have yielded mixed results.

 

[matt_i]

I personally think its best practice to ground each enclosure and wiring device with actual (green jacket) wire that's eventually tied back into the grounding bar.

 

[Bottlecapdigger]

Yes. I think it's code here. BCD

 

[mobiledynamics]

I actually thought that would be SOP - especially when the spark ran 6 wire for our hvac - which was not the case.

 

[Norcal]

It really depends, metallic conduit is a code compliant grounding conductor, and if a separate grounding conductor is run & not done correctly a bad situation is created during a fault. If a grounding conductor is run, then only one sized to the largest circuit is required. BTW since the location is listed as Norcal, no California power company offers either 110 or 220 volts as a supply voltage, 120/240, 120/208, are the only choices.

 

[bucktruck]

I personally think its best practice to ground each enclosure and wiring device with actual (green jacket) wire that's eventually tied back into the grounding bar.

That's what I ended up doing for the first lighting circuit I did tonight.

It really depends, metallic conduit is a code compliant grounding conductor, and if a separate grounding conductor is run & not done correctly a bad situation is created during a fault. If a grounding conductor is run, then only one sized to the largest circuit is required. BTW since the location is listed as Norcal, no California power company offers either 110 or 220 volts as a supply voltage, 120/240, 120/208, are the only choices.

The 110/220V thing was just for descriptive purposes, but thanks for the correction. It sounds like you are an electrician, so I appreciate the feedback.

 

[wyliesdiesels]

It really depends, metallic conduit is a code compliant grounding conductor, and if a separate grounding conductor is run & not done correctly a bad situation is created during a fault. If a grounding conductor is run, then only one sized to the largest circuit is required. BTW since the location is listed as Norcal, no California power company offers either 110 or 220 volts as a supply voltage, 120/240, 120/208, are the only choices.

You forgot 480Delta and 480Y/277

 

[Norcal]

You forgot 480Delta and 480Y/277

480 delta is not available to new customers in the PG&E system, and 480/277 is not a residential voltage, although have found 277 volt lighting in a residence. I did consider making the list a bit longer when writing the original post.

 

[thecj3man]

It really depends, metallic conduit is a code compliant grounding conductor, and if a separate grounding conductor is run & not done correctly a bad situation is created during a fault.

Can you explain how to do it not correctly or give an example? I am curious since my garage has EMT conduit and grounding conductors ran from the grounding bar for each circuit.

 

[sberry]

I was working on one of my own, I think it may have been my helper at the time gonna do it all alone in some scheme and found a missing nut the other day. It was on a steel purlin, it has wires pass completely thru it, the pipe didn't have offset so I added another clamp about a foot from the box.
I don't do it in most cases in my own steel building or to a section of pipe with a handi box and recept in it and got nothing against a plastic cover.

 

[wyliesdiesels]

480 delta is not available to new customers in the PG&E system, and 480/277 is not a residential voltage, although have found 277 volt lighting in a residence. I did consider making the list a bit longer when writing the original post.

It was a joke...

 

[Norcal]

It was a joke...

Was taken as such, I put the headscratch in because of the residential 277V. Just not something one would expect to find the in a dwelling.

 

[barnjunkie]

My first house was built in 1929. It had almost no grounding conductors at all with knob and tube wiring.

I never slept very well.

 

[wyliesdiesels]

Was taken as such, I put the headscratch in because of the residential 277V. Just not something one would expect to find the in a dwelling.

yeah i must say in all the weirdness Ive come across over the years, Ive never found 277v in a residence.

My first house was built in 1929. It had almost no grounding conductors at all with knob and tube wiring.

I never slept very well.

The absence of grounding conductors shouldnt cause alarm.

And original UNMODIFIED K+T was actually a really good wiring method. The issue with K+T was when people modified it

 

[Norcal]

yeah i must say in all the weirdness Ive come across over the years, Ive never found 277v in a residence.



The absence of grounding conductors shouldnt cause alarm.

And original UNMODIFIED K+T was actually a really good wiring method. The issue with K+T was when people modified it

Here is a photo of the shop panel that feeds the mother in law unit attached to the shop, the 15 KVA transformer supplies all the 120/240V power & the ITE panel is a mess too.

 

[wyliesdiesels]

Thats a 480v x 240/120v??

15Kva? What kind of loads?

Thats definitely weird

 

[Norcal]

Thats a 480v x 240/120v??

15Kva? What kind of loads?

Thats definitely weird

Yes, range, dryer, water heater are the major loads.

 

[wyliesdiesels]

Yes, range, dryer, water heater are the major loads.

*facepalm*

Only 15Kva for all that? That thing must be running near capacity with all that on.