240V Shared Neutral

[Kenny Rigler]

Hey Guys-

The two double-pole 30 amp breakers on the left share a neutral for two of the AC units. Under the 2008 code, these should be tied together, correct? This house was in 1997 so in that case would you call it as an electrical upgrade? The data plate also said max breaker size of 25 amp and these were on 30 amps.

Thanks

Kenny

[Robert Meier]

Those units should not require a neutral so it's likely that the white conductor is actually an EGC (would need to see terminations on both ends). Also since this in is not the service disconnect the neutral and grounds require separation. The 30 amp OCPD is no good with a MaxOCPD of 25 amps. Not sure what you're asking about the MWBC's.

[David A. Andersen]

There are no neutrals in 240vac hvac circuits.

Now that 120vac circuit that is double tapped is another issue. It is using equipment ground as a neutral. You call it as you see fit.

I see irrigation equipment added on like this all the time.
I call them back and tell them to add a neutral if they want to use the HVAC service. That means they need to add a neutral buss to separate the ground buss because there is none in those panels.

What is the chance for the ground to be utilized on an HVAC service?
100% when any component fails electrically.

[Robert Meier]

As long as the panel neutral is connected to the neutral bus ahead of the feeder that part of the installation is OK. The EGC can be the metallic offset nipple. That means that a separate bus for the EGC's is needed, bonded to the enclosure. That re-identified black conductor, with the white tape, is required to be #4 or larger or it needs white insulation. Looks like a #8.

[Kenny Rigler]

Originally Posted by Robert Meier

Those units should not require a neutral so it's likely that the white conductor is actually an EGC (would need to see terminations on both ends).

Thanks Robert and Dave. The inside panel had MWBCs and when I saw this I was thinking the same. I didn't think about the fact that the white conductor was a EGC since the ACs wouldn't have a neutral.

But yes, I had called it out anyway because of the double-tapped breaker and lack of separation. Thanks!