3 ph verses 1 ph disconnects

[Wgriffin]

On several different jobs in the past I have used a three phase disconnect as a single phase, and have started getting turned down on device not used as intended. And I actually agree. Here is the thing, I am doing a Univerisity and the engineer is using three phase disconnects as a single phase disconnect and swears it is ok. Who is right???
:smile:

 

[Cow]

turned down on device not used as intended.

That's silly. If the circuit is under the voltage/amperage rating of the disconnect, who cares how many phases it actually switches?

 

[ultramegabob]

I dont think there is anything wrong with it.

 

[infinity]

Many of the disconnects I've seen have a diagram inside of the door that depicts single phase connections. Where does is say that a 3 phase disco needs to have a 3 phase supply?

 

[iMuse97]

3Ph disco for 1Ph is standard practice where I'm from.

 

[Jim W in Tampa]

Sounds bit costly but see no violation.

 

[jim dungar]

The test requirements for 3-phase switches include 1-phase switching.

Imagine a 3-phase disconnect protected by fuses. If only one fuse blows, the there is no choice but to switch a 1-phase circuit.

 

[Wgriffin]

Device not used as intended??!!

Device not used as intended??!!

Please send me in the right direction. The engineer of my job says you can use a 3 phase disconnect on a single phase circuit, but the inspector says that I am not using the device as intended. What and where in the NEC does it say I can use a disconnect in this situation??
Thanks

 

[iwire]

I have never seen a three phase disconnect that can not be used on single phase.

You best bet is to find the info from the manufacturer of the disconnects that you are using.

 

[480sparky]

Please send me in the right direction. The engineer of my job says you can use a 3 phase disconnect on a single phase circuit, but the inspector says that I am not using the device as intended. What and where in the NEC does it say I can use a disconnect in this situation??
Thanks

It (the NEC) doesn't.

 

[chris kennedy]

Sounds like your inspector is grasping at 110.3(B). There is nothing in the NEC that prohibits the use of 2 poles of a 3? disco.

Or what those other guys said.

 

[iwire]

Wgriffin, I have merged your two threads asking the same question.

 

[iwire]

Reason: Old and slow.

Some of us had almost a months head start.

 

[djohns6]

I used one on my son's house , and the inspector never mentioned it .

 

[mcclary's electrical]

what about a four pole motor contactor on a three phase motor???? would he turn that down too??

 

[masterinbama]

How about a 2 pole pull out on a 120 volt VAV or air handler? Is that any different?