MWBCs....tell me again ?'s

[celtic]

I know we have discussed this previously - but...

Let's "say" I have a number of heaters(40) to be installed.
Something like this model:

Wall/Ceiling Mt Heater, Voltage Rating 120 Volts, Current Rating 8.3 Amps, Power Rating 1000 Watts, BtuH 3412, Finish Chrome
Grainger

The heaters are located quite a distance from the supply(3?), in a parking garage.
In an effort to save money (on copper) it was "suggested" that a 10/4 be run and branched out.
Each circuit will be on a single pole CB.

Q: Is this considered to be a multi-wire branch circuit?

 

[infinity]

Here's the definition, you decide:

Article 100 Definitions
Branch Circuit, Multiwire. A branch circuit that consists of two or more ungrounded conductors that have a voltage between them, and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system.

PS- I'd vote for yes. :wink:

 

[celtic]

Since this is a MWBC, would these single pole CBs now require an approved handle tie?

 

[infinity]

Since you consider this a MWBC, would these single pole CBs now require an approved handle tie?

Nope, handle ties are only required when the MWBC serves multiple devices on the same yoke or if it terminates at free standing office furniture partitions.

 

[celtic]

Gotcha.

I was having a brain-fart on this one...lighting circuits in an office area are also typically MWBC's...sans handle ties.
I just couldn't make the "connection" with the heater aspect.

Thanks.

 

[winnie]

Gosh, that is an annoying rating for a heater. See 424.3(B)

-Jon

 

[roger]

Celtic, you've got it.

Looking at the wording of 210.4 and 210.7, (I don't know why it is worded this way in 210.7 since 210.7 is specific to receptacles)

supplies more than one device or equipment on the same yoke,

I think that sentence could have been worded a little better since the word equipment covers such a wide area, it would have been better IMO to be something like "supplies more than one device on the same yoke
or piece of equipment contained in a single enclosure, frame, or housing"

As long as these elements (heaters) are in separate enclosures (separate pieces of equipment) the MWBC can be considered single circuits and not require handle ties.

If they were somehow factory installed in one enclosure, they would require the handle ties.

Roger

 

[celtic]

Thanks for taking the side trip here Roger.


I was totally baffled when you posted the " ..one device or equipment on the same yoke..." part in that other post.

Now that you have "bolded" it - it still doesn't make sense to me.

I'm fine with the one device on same yoke (120/240 outlet comes to mind).

What the heck is "...equipment on the same yoke..."???


I feel myself making a significant breakthrough on this MWBC thing...I just need a little more couch time :lol:

 

[iwire]

What the heck is "...equipment on the same yoke..."???

Two pilot lights on one yoke would qualify.

 

[celtic]

How about another example...I've never seen 2 pilot lights on one yoke (that I can recall)?

 

[petersonra]

How about another example...I've never seen 2 pilot lights on one yoke (that I can recall)?

I have seen pilot lights with 4 bulbs, separated into 4 quadrants.

 

[RUWired]

Celtic, Some of the sump pump motor starter contol panels require two circuits. One for the pump, and one for the alarm circuit.If you multiwired this equipment with a common neutral,then a common trip breaker would be required.
Rick

 

[infinity]

How about another example...I've never seen 2 pilot lights on one yoke (that I can recall)?

Here's a link to a PDF showing up to 3 devices or pilot lights on a single yoke:

http://www.passandseymour.com/pdf/T11-T12.pdf

 

[celtic]

Celtic, Some of the sump pump motor starter contol panels require two circuits. One for the pump, and one for the alarm circuit.If you multiwired this equipment with a common neutral,then a common trip breaker would be required.
Rick

Yes, but that's an "If you multiwired ", not an "equipment on the same yoke" comparison.

How about another example...I've never seen 2 pilot lights on one yoke (that I can recall)?

Here's a link to a PDF showing up to 3 devices or pilot lights on a single yoke:

http://www.passandseymour.com/pdf/T11-T12.pdf

How about "equipment" - not lights on a device/yoke.

I have no idea what they (CMP) mean by "equipment on the same yoke".

The examples you guys have given are simply "a multiwire branch circuit supplying more than one device ...on the same yoke".

 

[jwelectric]

Equipment. A general term including material, fittings, devices, appliances, luminaires (fixtures), apparatus, and the like used as a part of, or in connection with, an electrical installation.

 

[celtic]

Your missing the point...

210.4 states:
.....a multiwire branch circuit supplying more than one device or equipment on the same yoke ....

If a device is equipment, why add extra words?
The extra words don't clarify anything, they just add confusion.

 

[tincan44]

Here's a good example of a multiwire branch circuit supplying more than one device or equipment on the same yoke ....

how about a dishwasher and disposal plugged into a duplex recpt with the tab broken.

 

[celtic]

Here's a good example of a multiwire branch circuit supplying more than one device or equipment on the same yoke ....

how about a dishwasher and disposal plugged into a duplex recpt with the tab broken.

Is is a MWBC supplying the duplex?
Still not "equipment".

 

[tonyi]

How about "equipment" - not lights on a device/yoke.

A ubiquitous bath fan/light combo? They can be multiwired with fan on one leg, light on the other. Most aren't going to do it that way, but the multiple hot leads are usually in their j-box

 

[celtic]

How about "equipment" - not lights on a device/yoke.

A ubiquitous bath fan/light combo? They can be multiwired with fan on one leg, light on the other. Most aren't going to do it that way, but the multiple hot leads are usually in their j-box

Ok...I can see that happening .......someplace....LOL

BUT - that doesn't fit the wording (or does it?) of "...equipment on the same yoke .... "