240 volt loads connected with 120 volt multiwire branch circuits?

[slc410]

First off I know it is not allowed, but my question is what would be the "technical" ramifications of tapping a 240 volt load onto a 120 volt multiwire branch circuit? Neutral problems? Nuisance tripping?
Also I once had a master electrician have me run a 3-wire (black, red, white, ground) to feed a A/C unit (240 volt) disconnect and then tap off from one of the hots to feed a receptacle integrated in the disconnect. Legal?

 

[sparkyboys]

Also I once had a master electrician have me run a 3-wire (black, red, white, ground) to feed a A/C unit (240 volt) disconnect and then tap off from one of the hots to feed a receptacle integrated in the disconnect. Legal?

Sure, not a problem. mostly used for a work light anyways.

210.63

 

[Twoskinsoneman]

First off I know it is not allowed, but my question is what would be the "technical" ramifications of tapping a 240 volt load onto a 120 volt multiwire branch circuit? Neutral problems? Nuisance tripping?
Also I once had a master electrician have me run a 3-wire (black, red, white, ground) to feed a A/C unit (240 volt) disconnect and then tap off from one of the hots to feed a receptacle integrated in the disconnect. Legal?

There is no code (as is common) to say "hey you can do this specifically"...
But this one (see below) certainly shows that is ISN'T illegal. Although it does not spell it out per se... It does reference line-to-line loads that are a part of a MWBC. Basically what it comes down to is you have to have a 2-pole breaker (not just 2 single poles tied together) to have line-to-line loads..

210.4 Multiwire Branch Circuits.

(C) Line-to-Neutral Loads. Multiwire branch circuits
shall supply only line-to-neutral loads.
Exception No. 1: A multiwire branch circuit that supplies
only one utilization equipment.
Exception No. 2: Where all ungrounded conductors of the
multiwire branch circuit are opened simultaneously by the
branch-circuit overcurrent device.