Multiwire branch circuit on duplex receptacle

[hotneutral]

Can you have two multiwire branch circuits on one duplex receptacle? Hot tab is broken but there is 240V or 208V between hot terminals. Device is stamped for 125v 20A. I contacted P and S asking whether listing is for utilization or potential in the yoke. They sent me an email basically repeating what it said on the device. We never bother with this in installations due to the cost of 2 pole dual function breakers(I usually see this in dishwasher disposal receptacles) but I see this a lot in service work. anybody have any insight? thanks

 

[480sparky]

The common-disconnect requirement for this type of installation is relatively recent.

 

[infinity]

So you have two circuits on a duplex but not from the same MWBC? Those two circuits require a simultaneous disconnecting means been in the NEC for decades.

 

[hotneutral]

The receptacle is fed from both legs of a multiwire branch circuit. Two pole breaker. both disposal and dishwasher are cord and plug so no need for breaker lock or other disconnecting means. I’m asking about whether the receptacle is rated for 125v utilization or 125v on the yoke. Putting a multiwire branch circuit on on duplex would create more than 125 between the hot terminal screws and I wonder if that violates the listing.

 

[480sparky]

So you have two circuits on a duplex but not from the same MWBC? Those two circuits require a simultaneous disconnecting means been in the NEC for decades.

For dwellings, the requirement goes back to 1981. The 'dwellings only' portion disappeared in 2005.

 

[hotneutral]

Yes I am aware of that. My concern was more with the listing of the devices especially after the noncommittal response I got from P and S. Just because NEC allows something doesn’t mean that it applies for the individual products we buy from the supply house. Thanks for the replies.

 

[infinity]

The receptacle is fed from both legs of a multiwire branch circuit. Two pole breaker. both disposal and dishwasher are cord and plug so no need for breaker lock or other disconnecting means. I’m asking about whether the receptacle is rated for 125v utilization or 125v on the yoke. Putting a multiwire branch circuit on on duplex would create more than 125 between the hot terminal screws and I wonder if that violates the listing.

OK that makes more sense your OP said that you had 2 MWBC's on one duplex receptacle. Yes, a duplex receptacle is two receptacles they can be split wired as individual receptacles as long as you meet the simultaneous disconnect rule.

 

[don_resqcapt19]

From the UL Guide Information for "Receptacles for Plugs and Attachment Plugs (RTRT).

Duplex receptacles rated 15 and 20 A that are provided with break-off tabs may have those tabs removed so that the two receptacles may be wired in a multi-wire branch circuit or multiple branch circuits.

Assuming the receptacle is listed, it is permitted to break off the tabs and connect two individual circuits or a mutliwire circuit to a 15 or 20 amp duplex receptacle.

 

[LarryFine]

I've done it several times, and I always widen the gap farther with a flat-blade driver.

 

[winnie]

IMHO this is one of those things that should be in datasheets but good luck finding the info.

The receptacle has its NEMA configuration voltage rating.

It should also have a maximum usable voltage rating and a maximum rating between the two sides. But I don't recall ever seeing this information.

My vague hear-say understanding is that 5-15 and 6-15 receptacles are electrically the same, and constructed the same, simply with different mechanical configuration. I would have no problem breaking the tab and wiring a 5-15 duplex on a MWBC, putting 240V on adjacent screws.

But I wouldn't do the same thing with this: https://www.legrand.us/passandseymour/receptacles/miscellaneous-configurations/5762.aspx

-Jon

 

[hotneutral]

Thanks everyone for the information. Those are the answers I was looking for.

 

[Dennis Alwon]

You are only using each receptacle for 120V so there is no issue. You just need a dp breaker or 2 sp breakers with a breaker tie.