Motors and MWBCs

[JohnJ0906]

I was having a discussion with my new boss, and he was telling me that it was wrong to put 2 motors on a MWBC, due to overloading of the neutral.
I hadn't ever heard this, so I decided to run it by you guys.

This would be a residential application. For instance, 2 outlets for window A/C units, each on its own circuit, fed with a MWBC.

 

[Dennis Alwon]

I was having a discussion with my new boss, and he was telling me that it was wrong to put 2 motors on a MWBC, due to overloading of the neutral.
I hadn't ever heard this, so I decided to run it by you guys.

This would be a residential application. For instance, 2 outlets for window A/C units, each on its own circuit, fed with a MWBC.

I am not sure why a motor would make a difference. If one motor draws 10 amp and the other 12 amps the ungrounded conductor would only draw 2 amps.

I see refrigerators and dw on the same MWBC as well.

 

[iwire]

He is mistaken.

 

[infinity]

He is mistaken.

Short, concise and to the point. I agree with Bob, unless you somehow had the ungrounded conductors on the same phase sharing a neutral.

 

[JohnJ0906]

Bump.

Any other input?

 

[peter d]

Bump.

Any other input?

Sure. I agree with Bob.

Seriously though, by his own statements your new boss clearly does not understand how a MWBC works.

 

[stickboy1375]

Bump.

Any other input?

Nows your chance to show him how smart you are... :grin:

 

[iaov]

I've put two different refridgerators on an MWBC already. No problems!!

 

[peter d]

I've put two different refridgerators on an MWBC already. No problems!!

Of course there isn't. The load or type of load has nothing to do with the safe operation of a MWBC.

 

[mivey]

Nows your chance to show him how smart you are... :grin:

Don't forget to point out how dumb he is.:grin:

 

[chris kennedy]

Don't forget to point out how dumb he is.:grin:

Theres the post of the week.:smile:

 

[JohnJ0906]

Nows your chance to show him how smart you are... :grin:

Don't forget to point out how dumb he is.:grin:

Well, so much for showing this thread to him......:roll:

Actually, in our discussion, I think he was trained originally by one of the anti-MWBC people. He gave most of the same reasons against them as we hear from the members we have here that don't like them.

 

[frenchelectrican]

John.,,

Let me step in I done quite bit of motor work on MWBC and I don't see any issue with it as long you set it up right.

That go for both single and tri phase system.

Merci,Marc

 

[mivey]

Well, so much for showing this thread to him......:roll:.

Hey! Bossman!

We know you are not really dumb, we were just joking around to keep discussions from getting so dry. The same goes for your employee, we were just joking...no wait, he really is smart because he thought something about the statement you made about motors & MWBC sounded fishy.

How about the two of you sitting down and talking throught the reasons why what you were initially thinking was wrong. Perhaps it was just something you heard from somebody else and you just need to think it through. It would be a good lesson to get this clear in your minds so y'all can explain it to others. Let us know if we can help.

All better now JohnJ?:smile: