Air Conditioner power

[paulhiggs]

I am re-wiring my basement air conditioner to a new sub-panel. It has a 4-wire connection (2 hots, 1 neutral and 1 ground) at the breaker panel, but in the unit, the neutral and ground are connected together.
When this unit was wired to a breaker in the main panel, this probably was OK as the neutral and ground bars are bonded together there. In the sub-panel the bars are isolated.

Should the air conditioner be re-wired now that it is connected to a sub-panel? Under the wiring cover it only shows connections for the two hot and a ground. Its an older (1995) Trane XE1000 model TTR018C1000A1.

Paul

[HayZee518]

when the wiring code first came out long ago, only equipment connected in a mobile home was required to have a four wire configuration - i.e. dryer or electric range. any plug and receptacle equipment like an air conditioner only needed three wires - two hots and an equipment ground [bare, green, yellow with green stripe]
Since the adoption of the "new" code all "new" construction is required to have a three pole four wire configuration. Electric ranges and dryers as supplied can be wired either or three wire or four wire. If used as a replacement in a house where only a three wire feeder was it can use a three wire pigtail. Same goes with a range. In new construction it has to have an isolated green ground, that is, the neutral and earth ground is seperate. In the case of your a/c as shown there is NO neutral just an equipment ground, so use it as such. Two hots and a ground. Put the ground to the aux strip in the sub panel.

[paulhiggs]

In the case of your a/c as shown there is NO neutral just an equipment ground, so use it as such. Two hots and a ground. Put the ground to the aux strip in the sub panel.

So I should disconnect the neutral either at the sub panel or a/c unit. Right now it is wired as below, causing a bridge between the neutral and ground busses in the sub panel via the a/c unit.

15A hot----------------------------power
15A hot----------------------------power
neutral-----------------------|
ground------------------------+----ground

My understanding was that there should only be one ground-neutral bond and that must be in the main panel.

[HayZee518]

In a sub panel the neutral is not bonded via a screw or bonding jumper to enclosure ground, just the auxillary ground bus [strip] - AT the main panel which feeds your sub-panel both the white neutral and equipment ground goes to the neutral bus. Here in your main panel the main box's neutral is bonded to the enclosure ground. normally there is no auxillary ground bus although somebody may have installed one. [no biggie]

[paulhiggs]

Thanks. I'll leave it wired as is, now that it is moved to the sub panel. Yes, my main panel has a separate ground bus, which seems to keep the wiring "cleaner.

[flenhellis]

Thanks for your information, It would be helpful for me,,,