Supply to A/C disconnect

[randynavarro]

I think this might be really simple, but something isn't sitting quite right in my head.

The picture shows a pair of wires (240v) exiting the main panel via EMT.

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Outside showing the EMT

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Here's the wiring at the disconnect.

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Is it all ok?

[Chad Fabry]

Is the unit chassis bonded to ground?

[randynavarro]

Is the unit chassis bonded to ground?

I can't say 100%. I know the green grounding wire in that 3rd pic. runs out of the disconnect box, thru the flex conduit (plastic - I forget the name of it right now), and into the A/C housing. I'm assuming it's bonded inside the A/C housing. . .

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Does anyone check wiring connections inside the A/C housing?

[Terence McCann]

thru the flex conduit (plastic - I forget the name of it right now),

Are you thinking of Sealtight?

Where did they pickup the ground from Randy?

[randynavarro]

Where did they pickup the ground from Randy?

Not sure I follow the question. . . .I thought Chad asked sort of the same question. Maybe I'm confused.

Grounding path from A/C unit back to main panel is via green grounding wire back to main panel via the EMT.

[Terence McCann]

Where did they pickup the ground from Randy?

Not sure I follow the question. . . .I thought Chad asked sort of the same question. Maybe I'm confused.

Grounding path from A/C unit back to main panel is via green grounding wire back to main panel via the EMT.

I only see two wires leaving in your first picture.

[Jeff Remas]

The emt is the grounding conductor, the green wire is the ground for the equipment that the disco serves.

[randynavarro]

The emt is the grounding conductor, the green wire is the ground for the equipment that the disco serves.

Yea, that's what I said . . . maybe sorta.

So it's all ok?

[Carson2006]

Yup! Seems like "someone" used the EMT as an equipment grounding conductor. Ok for the most part, however, notice the paint under the connector in the main panel. Too easy to make it a better, safer installation by running a EG conductor back to the main panel's grounding bus. Plus, not a good idea to use conduit as an EG when there are concentric/ecentric K.O.s. Believe it violates NEC; 90% sure.

[Jim Katen]

Yup! Seems like "someone" used the EMT as an equipment grounding conductor. Ok for the most part, however, notice the paint under the connector in the main panel. Too easy to make it a better, safer installation by running a EG conductor back to the main panel's grounding bus. Plus, not a good idea to use conduit as an EG when there are concentric/ecentric K.O.s. Believe it violates NEC; 90% sure.

You can't rely on the knockout for grounding for circuits that are over 250v or for the bonding of the service. As far as I know, the knockouts aren't a problem on branch circuit equipment grounds.

You make a good point about the paint. If you're using the EMT as the equipment ground, and if the box is painted, then you're supposed to remove the paint at the locknut to ensure a good connection.

- Jim Katen, Oregon

[Tom Raymond]

"You make a good point about the paint. If you're using the EMT as the equipment ground, and if the box is painted, then you're supposed to remove the paint at the locknut to ensure a good connection."

So how common is it to see the paint removed? And shouldn't the same prep be at the accessory ground bus in the disconnect (or any accessory bus for that matter)?

Tom

[randynavarro]

And shouldn't the same prep be at the accessory ground bus in the disconnect (or any accessory bus for that matter)?Tom

I would think because the equipment is assembled at the factory, that those bond and connection points are ok.

It's when field modifications are made that the paint may become a problem.

I could be wrong though.

[Jim Katen]

. . . So how common is it to see the paint removed? And shouldn't the same prep be at the accessory ground bus in the disconnect (or any accessory bus for that matter)?

Uncommon.

At the accessory grounding terminal, I believe that the electrica connection is made via the mounting screws.

- Jim Katen, Oregon