dual voltage from ocpd,referencing an old post.

[rong111]

in reference to:http://www.mikeholt.com/cgi-bin/codeforum/ultimatebb.cgi?ubb=get_topic;f=11;t=003069

is what i am writing below the same thing as what is found in this old post?

i was in a home that has a 15amp double pole ocpd with one leg going to a 120v recept(neutral present on recept). that leg continues on to one leg of a 240v pump. the other leg of the double ocpd goes straight to the pump. the pump is bonded by being attached to the water pipe.

could someone please reference what the nec says about this? (210-4(c) Exception #2?)
i think this is shoddy work but not really a problem since it is only a 15 amp breaker, right?

thank you,
ron g.

 

[rong111]

Re: dual voltage from ocpd,referencing an old post.

while i was looking for my answer to the above post, i saw this and am sure i am missunderstanding it!

"225.33 Maximum Number of Disconnects.
(B) Single-Pole Units. Two or three single-pole switches or breakers capable of individual operation shall be permitted on multiwire circuits, one pole for each ungrounded conductor, as one multipole disconnect, provided they are equipped with handle ties or a master handle to disconnect all ungrounded conductors with no more than six operations of the hand."

does this apply when the disconnect IS the ocpd?
one single pole breaker can feed one leg of the recept and pigtail onto the pump. another single pole breaker can feed the other leg of the pump.

since the neutral goes to the recept this setup can allow the combined total draw of the recepts and the pump to be more than 15 amps at once(with two single pole 15 amp breakers shared). because of the differential to the neutral.

if something plugged into the recepts draws 12 amps and the pump draws 9 amps (simultainously) neither breaker should trip in this situation.

now, of course the big deal here is "handle ties"

i thought "handle ties" to make two single breakers into a double pole is strictly forbidden?

i realize this is different than my original question. but as i discover stuff i didnt know existed in the nec i like to get it clarified!

thanks again,
ron g.

 

[jim dungar]

Re: dual voltage from ocpd,referencing an old post.

For what it is worth, the 2005 NEC handbook says this multi-wire circuit is acceptable under 210.4(C) and gives an example (exhibit 210.2) of a combination 240V and 120V receptacle.

 

[rong111]

Re: dual voltage from ocpd,referencing an old post.

thank you. i actually just stumbled upon that one like 10 seconds before you posted it! i am glad you agree though. the nec leaves so much open to interpretation.

as for my question about handle ties, i got that answer too. they are disconects only.

now my only question left is: this really would be better on two single poles. because of what i stated above. by having line to line and line to neutral withOUT a common trip breaker should allow the pump and recepts together to exceed 15 amps draw on this branch. while still properly protecting the branch. the nec says nowhere i can find that if only 1 leg of a line to line were to trip is illegal. so i guess the nec does not care if that 240v load is still being feed 120 in a fault situation! they only care that it can be disconnected simultainously!

so in case you didn't want to read that all....
this branch being fed by 2 single poles with a approved "handle tie" is acceptable? or it has to stay with a common trip breaker?(breaker trips both legs internally).


thanks,
ron g.

 

[rong111]

Re: dual voltage from ocpd,referencing an old post.

getting more confused.

does this multi-wire branch require a common trip because half of it is line to line.... or can it use two single poles because half of it is line to neutral? looking at 240.20(B)exception (2).
also, 210.4(c) exception 2. contradicting?

thanks,
ron g.

[ June 30, 2005, 02:23 PM: Message edited by: rong111 ]

 

[rong111]

Re: dual voltage from ocpd,referencing an old post.

240-20(2). does this answer my question? you CAN use 2 single pole breakers with approved handle ties for this application.


ron g.

 

[milwaukeesteve]

Re: dual voltage from ocpd,referencing an old post.

You cannot do this type of installation.
210.4 talks about mulitiwire branch circuit. These are two different voltage types for loads.

What you SHOULD have for this example is not a multiwire branch circuit. What you SHOULD have is 2 different circuits.
-a 120V circuit
-a 240V circuit

They cannot share the same conductor - especially a hot.


About the handle tie; that is for when 2 circuits are present on the same device (i.e. top and bottom of a duplex recept), then those 2 circuits would both need to disconnect together for servicing.


Unless specifically listed in the code, or listed by the manufacturer, this example is not a legal way of wiring circuit(s).

 

[milwaukeesteve]

Re: dual voltage from ocpd,referencing an old post.

i thought "handle ties" to make two single breakers into a double pole is strictly forbidden?

It is not, almost. It is designed, as I just mentioned, to 'tie' together 2 or 3 single pole breakers WHEN used in a MULTIWIRE branch circuit WHEN circuits are located on a single yoke.

They are not to be used in place of a 2pole or a 3pole breaker for NON multiwire branch circuits(i.e. welders, breakers, stoves, wells...)

 

[iwire]

Re: dual voltage from ocpd,referencing an old post.

Originally posted by milwaukeesteve:
You cannot do this type of installation.
210.4 talks about mulitiwire branch circuit. These are two different voltage types for loads.

What you SHOULD have for this example is not a multiwire branch circuit. What you SHOULD have is 2 different circuits.
-a 120V circuit
-a 240V circuit

They cannot share the same conductor - especially a hot.

Steve, Yes you can feed both a 120 volt load and a 240 volt load with the same multiwire branch circuit.

Take a look at 210.4(C), then read the exception Exception No. 2

 

[iwire]

Re: dual voltage from ocpd,referencing an old post.

Here is a 240/120 device that could be fed with a single multiwire branch circuit.

 

[milwaukeesteve]

Re: dual voltage from ocpd,referencing an old post.

Yes, 210.4 (C) has an exception, but that would mean that you use the black and the red for the 2pole and the blue for the 120V.
This is not talking about sharing a phase/ungrounded conductor. This section is about using multi WIRES, not multiCIRCUITS per wire.

[ June 30, 2005, 05:34 PM: Message edited by: milwaukeesteve ]

 

[iwire]

Re: dual voltage from ocpd,referencing an old post.

Originally posted by milwaukeesteve:
Yes, 210.4 (C) has an exception, but that would mean that you use the black and the red for the 2pole and the blue for the 120V.
This is not talking about sharing a phase/ungrounded conductor. This section is about using multi WIRES, not multiCIRCUITS per wire.

Steve I do not need a 'blue'

I could use a 12/3 cable to feed the device I pictured above.

Black / White for the 120 portion

Black / Red for the 240 portion.

There is no reason I can not share an ungrounded conductor between a 120 load and a 240 load.

Electrically this is no different a dryer that has 240 volt heating elements and a 120 volt motor. (210.4(C) Exception No. 1)

 

[rong111]

Re: dual voltage from ocpd,referencing an old post.

i agree with jim and iwire!
iwire i had seen you post about this exact thing on another forum a long time ago.

anyways all i need to know now, is does this type of circuit HAVE to be fed by a double pole(common trip) breaker? or are two handle tied singles ok?

reason i am asking is because, if the 240v pump draws 9 amps and then a 9 amp sump pump is plugged in the 120v recept, this will trip a common trip breaker but probably not two singles. since as i said before the common trip breaker will not allow the line and neutral to reach the differential,correct? as far as i can see the nec does not care if a line to line trips only one line and leaves it energized with 120v in a fault situation. it only refers to being able to DISconnect both breakers at the same time, hence the tie bar. i am talking about two 15 amp singles vs. a 15 amp common trip. but i just realized that since a line is being shared if i want it to draw more than 15 amps(recept and pump combined) it cannot be a #14 anyways?

if i am correct that two singles with a tie bar is ok for this 240/120(mwbc) then they are all set. the only reason this is important is because their emt is already full of it(conductors that is). otherwise pulling another conductor would be cake.


thanks,
ron g.

[ June 30, 2005, 07:34 PM: Message edited by: rong111 ]

 

[LarryFine]

Re: dual voltage from ocpd,referencing an old post.

First of all, since even part of this circuit feeds a single line-to-line load, I would use a two-pole breaker, period. It would be too easy for someone to believe they've de-energized the equipment if they observe or hear it stopping after switching one pole off.

Personally, I have no trouble connecting both line-to-neutral and line-to-line loads to a multi-wire circuit, as long as all neutral joints do not depend on a device for continuity, and as long as all poles are switched together for the sake of the line-to-line loads.

Second, with the exception of QO breakers, it seems that almost all two-pole breakers ARE two single-pole units, riveted together, with a handle tie. If you pry a tie off, the two poles operate individually just as two single-pole units would. Where is the "internal common trip"?

It looks external to me.

 

[LarryFine]

Re: dual voltage from ocpd,referencing an old post.

By the way, Ron, if you have 9 amps on the line-to-line and 9 amps on the line-to-neutral, there will be an overload on one line.

One line will have 9 amps, one will have 18 amps, and the neutral will have 9 amps. The line with the 18 amps will indeed trip.

 

[iwire]

Re: dual voltage from ocpd,referencing an old post.

Originally posted by LarryFine:
with the exception of QO breakers, it seems that almost all two-pole breakers ARE two single-pole units, riveted together, with a handle tie. If you pry a tie off, the two poles operate individually just as two single-pole units would. Where is the "internal common trip"?

It looks external to me.

Take a couple of minutes to drill out the rivets of these breakers and you will find a small metal bar passing through the center of all two or three breakers.

I already did it one day while board and curious.

 

[rong111]

Re: dual voltage from ocpd,referencing an old post.

i was wondering if a handle tie on two singles will satisfy the disconnect requirement AND the fault requirement. or if it needs to be a common trip to satisfy the fault requirement?
does the double pole breaker allow the same maximum current draw from the line to line and line to neutral simultainiously as does two single pole breakers in this application? i would think two single poles would let the 120 recept run up to 15 amps concurrently allowing the 240v pump to also draw up to 15 amps. since the lines are 180 phase apart. whereas the double pole will only allow a combined total draw of 15 amps from both the 120 and 240 legs before it trips.
i am talking about 2 15amp single poles(with handle tie) vs. 1 15 amp double pole common trip.

also, iwire do you know if that recept you pictured is allowed to be used in the application you stated where it is ganged to more than one of those? i.e. 2 or more of those split 240/120 recepts in series from the red/black/white.

 

[jim dungar]

Re: dual voltage from ocpd,referencing an old post.

The NEC does not require a common overcurrent protection trip of 240V devices (ungrounded conductors) other wise we would never be able to use fuses.

The NEC does require a common disconnection of all ungrounded conductors.

edit: added OCP

[ June 30, 2005, 11:40 PM: Message edited by: jim dungar ]

 

[rong111]

Re: dual voltage from ocpd,referencing an old post.

staying up late thinking about this....
first of all i realized larry was right. it does not matter if it was a double or single pole breaker. if one pump drew 9 amps and another drew 9 amps at the same time one line would see 18 amps this would trip one of the single poles and it would trip the double pole. also jim i am glad you read this part of the nec the same way as i do. 2 single pole breakers can feed a 240v line as long as the 240v line has another means of total disconnect. like i have said 3 times i beleive that the nec does not care if a fault situation closes one line(2 single poles) and leaves one open. all it cares about is a means of total disconnect.

so now am i assuming correctly that the only reason double pole breakers exist is to a) feed a split duplex mwbc. and b) if they are the ONLY means of disconnect on a 240v line to line circuit.

one more thing, if 2 single pole breakers are used to feed a 240v line to line, is the disconnect required to be a lockout or can it be a 2 pole switch located within 6 feet of the device being supplied?


thank you for all your help on this guys!
ron g.

[ July 01, 2005, 12:55 AM: Message edited by: rong111 ]

 

[milwaukeesteve]

Re: dual voltage from ocpd,referencing an old post.

WAIT A MINUTE!!

Don't thank those guys too soon.

First- you cannot install two circuits like this. They are different CIRCUITS! They can NOT share a common breaker.
Second- Multiwire Branch circuit means multiple CIRCUITS sharing a common NEUTRAL, not that the share a common hot. NOTE: the code rule is 'Line to Neutral Loads' NOT 'Line to Line' loads.
Third- 'Tying' handles together is allowed to tie breaker handles together from DIFFERENT circuits that are present on the same YOKE. It is NOT used to make a 2pole breaker out of 3pole beaker.
Fourth-

Electrically this is no different a dryer that has 240 volt heating elements and a 120 volt motor. (210.4(C) Exception No. 1)

This is VERY different, because that is a manufactured item in is UL LISTED FOR THAT PURPOSE.

Fifth- IWIRE, That example device that you have pictured is NOT for wiring using the SAME circuit. To properly wire this, you would need 4 conductors (2 hots, and a hot and a neutral). AND you would need a 2pole and a 1pole breaker AND THESE WOULD HAVE TO BE HANDLE TIED TOGETHER/

and finally- I am tired of being pointed to 210.4(c) exception 2 as the reason for allowing 240V loads, when the section is titled and is a section about LINE TO NEUTRAL LOADS ONLY!!!