Neutral Needed??

[Alwayslearningelec]

Attached is pic of panel schedule and unit schedule for these two units. It's a 3P4W panel, not sure why that would matter.
It's a pump that's being feed. So according to the schedule it's just one phase conductor but I would certainly pull a separate ground for a unit like this. My question is how does one determine if a neutral would be needed? I know a lot of motors don't need a neutral.

 

[LarryFine]

My question is how does one determine if a neutral would be needed? I know a lot of motors don't need a neutral.

No motor requires a neutral (grounded conductor) per se, but does require two conductors (3 for 3ph).

A motor rated at 115v will receive one because our 120v supplies almost always happen to include one.

 

[Alwayslearningelec]

No motor requires a neutral (grounded conductor) per se, but does require two conductors (3 for 3ph).

A motor rated at 115v will receive one because our 120v supplies almost always happen to include one.

You say a motor requires 2 conductors( that would be 208v. But if it's a case like this 120v it would only require one conductor, a hot??

 

[winnie]

On a 208/120V system.

A motor rated 115v will receive one _neutral_. Two conductors, a hot and a neutral. The 115V rating implies single phase, and the system implies a hot and a neutral.

A single phase 208V motor will receive two hots, but no neutral.

A three phase 208V motor will receive three hots, but no neutral.

-Jon

 

[infinity]

You say a motor requires 2 conductors( that would be 208v. But if it's a case like this 120v it would only require one conductor, a hot??

I don't think that what you wrote is what you actually meant, a circuit requires a least 2 conductor.

 

[LarryFine]

9You say a motor requires 2 conductors( that would be 208v. But if it's a case like this 120v it would only require one conductor, a hot??

No, a 120v load only requires one "line" (ungrounded, i.e., hot, from a breaker) conductor, but still requires two wires to form a complete circuit.

No load can function when supplied by only a single conductor; current requires a circuit, so (at least) two wires are needed. Look at a lamp cord.

Don't confuse an EGC (grounding conductor) and a neutral (grounded conductor). You cannot use the EGC as a current-carrying circuit conductor.

A load does not care whether one of its supply conductors is grounded, only that the voltage between (or among) them is suitable for the load.

 

[retirede]

No, a 120v load only requires one "line" (ungrounded, i.e., hot, from a breaker) conductor, but still requires two wires to form a complete circuit.

No load can function when supplied by only a single conductor; current requires a circuit, so (at least) two wires are needed. Look at a lamp cord.

Don't confuse an EGC (grounding conductor) and a neutral (grounded conductor). You cannot use the EGC as a current-carrying circuit conductor.

A load does not care whether one of its supply conductors is grounded, only that the voltage between (or among) them is suitable for the load.

Then we have SWER!

 

[Alwayslearningelec]

No, a 120v load only requires one "line" (ungrounded, i.e., hot, from a breaker) conductor, but still requires two wires to form a complete circuit.

No load can function when supplied by only a single conductor; current requires a circuit, so (at least) two wires are needed. Look at a lamp cord.

Don't confuse an EGC (grounding conductor) and a neutral (grounded conductor). You cannot use the EGC as a current-carrying circuit conductor.

A load does not care whether one of its supply conductors is grounded, only that the voltage between (or among) them is suitable for the load.

Yes I thought so..lol. So even though it doesn't require a neutral and it's a 120v circuit 1 phase your still pulling a neutral as the 2nd conductor?

 

[LarryFine]

Yes I thought so..lol. So even though it doesn't require a neutral and it's a 120v circuit 1 phase your still pulling a neutral as the 2nd conductor?

Exactamundo. It doesn't require that either conductor be grounded, but it requires two conductors.

The fact that one conductor happens to be grounded is merely a characteristic of the source.