Should the 220 volt neutrals be on the same buss as 110v neutrals in a sub-panel?
One you go past the service disconnect the grounded and grounding conductor must be separate, this applies to the sub panel. This would apply to both 120 volt and 240 volt circuits.
So how do I tell if the “white” wires on the 240 are neutrals or grounds or needed at all?
Just wondering, since it’s hard to tell from the photo but where does that white conductor originate? Does it come from a cable or is it a pigtail from a circuit breaker?
The white conductor should never be a grounding conductor and should terminate on the neutral bus in a sub panel.
There are 3 240v circuits and 3 white conductors (black and reds connected to breakers) connected to the ground buss.
Since this a subpanel the neutrals must be connected to the neutral bus in the panel not the equipment grounding bus. By connecting them to the EGC bus neutral current is now flowing on the EGC of the subpanel feeder back to its source. Under normal conditions current should never flow on the EGC.
Robert’s got it…
Robert is correct, but to help clarify -
The neutral conductor of a 240V circuit can/will carry current from the unbalanced circuit. So even in a 240V circuit, the neutral is a current-carrying conductor and must remain “ungrounded” until it has returned to the service equipment.
Most 240V circuits installed today will require four conductors - H+H+N+G.
Thanks everyone!!!
In your picture I see other nuetrals and grounds and the terminal it’s on looks green in the picture. So it looks like they are sending the white wire to ground since in subpanel the nuetral and ground should not be bonded. It is ok to have 115 and 240 terminate in the same place. You don’t say what it’s running but things like stoves and dryers now require a 4 wire system since they have 115v controls and with a 3 wire it would have a false ground. Either way in your picture it looks like there is at least one issue going on.
House built in 1990. Do you recommend to your clients upgrading old 3 wire (3 prong plugs for dryer and stove) to 4 wire systems? The 3 circuit is the AC condenser.
No, I do not.