dual voltage from ocpd,referencing an old post.

[roger]

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

Steve,

Second- Multiwire Branch circuit means multiple CIRCUITS sharing a common NEUTRAL, not that the share a common hot

read 210.4(A), you will notice a Multiwire Branch Circuit (as in one circuit) shall be permitted to be considered Multiple Circuits, not mandatory that it is.

Look at it this way, you have one 3 conductor MWBC circuit (L1-L2-N) and the 3 conductors of this circuit could be used on one device regardless of how the load devides for the equipment

Roger

 

[don_resqcapt19]

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

Steve,
I have never seen the device that Bob posted wired with other than a single circuit. That device is commonly installed for use as an window air conditioner outlet when the voltage of the future AC is unknown. Sometimes the same circuit that feeds the dual voltage receptacle is also used to feed the electric baseboard heat in the area. A two pole breaker with two hot and grounded conductor is used to feed the receptacle.
Exception #2 to 210.4(C) is exactly that ... an exception to the main rule that says "Line-to-Neutral Loads. Multiwire branch circuits shall supply only line-to-neutral loads".
Don

 

[iwire]

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

Steve....chill out man.

You have to stop thinking that a multiwire branch circuit can only be used in the way you have used one.

Sorry if you 'sick' of being pointed to the 210.4(C) exceptions but they are the rules that allow this.

Let me ask this.

What do you see as the safety hazard with powering the device I pictured above sharing an ungrounded conductor between the 120 and 240 outlets?

 

[rong111]

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

this is a problem with the nec. it leaves so much open to each persons inerpretation.

so let me explain exactly what i am talking about here. i think 210.4(c) exception 2 is specifically for that EXACT product(recept) that iwire showed. workers that power another hardwired device with the line to line i think is not legal?

here is what i saw. 2 single pole breakers feed l1 and l2. neutral from the panel. l1 and neutral go to a 120v recept. l1 is pigtailed to a two pole disconect. l2 goes to the other side of this two pole disconect. now the disconect goes to a hardwired pump. so you have a hardwired pump running line to line at 240v. and a recept running at 120v from the same circuit.
this is of course all grounded since the conductors are running through emt all the way back to the panel. however the 240v pump is a 2 wire 12/2(wetjacket) and is not grounded. it runs pvc water pipe.

i always think my questions are going to be thought of as stupid by other professionals in the field. and i am always surprised to find out that it isn't stupid because other people are having issues with it also!

the big problem we are having is that the nec cant say exactly everything you can and cannot do.
it would be 10 million pages long. so i am just going to go with whoever comes up with the most convincing yay or nay on this one....


thank you,
ron g.


edit: i am now wondering if the whole 210.4 section is supposed to be understood as being used only for the clothes dryer that has been mentioned. or any other device that INternally divides the mwbc. so in this case the recept would be a single with l1-l2-n/g.

anyhow this passed inspection. plus i am not the person that did this work. i was just asked to look at something else and happened to notice this. which is what got me (and all of us) wondering about it. and i really want to know the answer to this since ive seen it before and will again.
however! we all know that just because it passed inspection does not mean it is acceptable.

ron g.

[ July 01, 2005, 07:11 PM: Message edited by: rong111 ]

 

[rong111]

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

well i am assuming this is ok since no one has said otherwise at this point, and:
a) it passed ahj.
b)a line to line 240v does not require a double pole breaker if there is a common disconnect at the device.
c) people wire this multi circuit mwbc apperantly all the time. this would be the same as the person that mentioned that the unit iwire spoke of is often ALSO wired to 240v baseboard heaters.
so this seems to be a similar installation which is why i guess it passed.

even though this was not my work. i will probably employ this technique in the future since i find so many boxes out of spaces and it saves a breaker.

ron g.

 

[LarryFine]

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

Originally posted by milwaukeesteve:
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!!!

I'm sorry it's tiring to you, but the exception is what it is: "Exception No. 2: Where all ungrounded conductors of the multiwire branch circuit are opened simultaneously by the branch-circuit overcurrent device."

The section is "210.4 Multiwire Branch Circuits.", and the rule is "Multiwire branch circuits shall supply only line-to-neutral loads" except "Where all ungrounded conductors of the multiwire branch circuit are opened simultaneously by the branch-circuit overcurrent device."

Originally posted by rong111:
b)a line to line 240v does not require a double pole breaker if there is a common disconnect at the device.

No, read exception 2 again: "Exception No. 2: Where all ungrounded conductors of the multiwire branch circuit are opened simultaneously by the branch-circuit overcurrent device." This is a case where fuses would not suffice.

 

[rong111]

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

so all that this needs is a double pole breaker. otherwise it can stay exactly as it is(with the double pole breaker installed)?

that is sttrange since other parts of the nec state that a double pole breaker is NOT required to serve line to line loads(hence fuses). i guess when it serves ungrounded and a neutral they want a double pole.
if this is the case it is stil good news. because it is one less conductor and one less breaker than if this had to be seperate circuits.

edit: can exception (2) be handle ties or it must be a common trip? i am not getting super lazy here i am just wondering

thank you,
ron g.

[ July 02, 2005, 10:10 PM: Message edited by: rong111 ]

 

[rong111]

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

it has to be a common TRIP ocpd. i read it more carefully. otherwise if the ocpd opened on a fault the other line would still serve the fault and create a hazardous situation.

the only thing i think people may still be misunderstanding is that 210.4 in regard to serving ungrounded and neutral is that it was speciffically in regard to recepts. ie devices that ONLY plug in. i do not think it was intended to serve a 120v recept and a 240v hardwired device. everyone seems to disagree on this one. i wish someone had a definitive answer. i guess the only person that knows is whoever wrote 210.4!


thanks,
ron g.

 

[milwaukeesteve]

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

You guys are reading that exception #2 wrong.

It states that you can use other than line to neutral loads IF all ungrounded conductors are simultaneously tripped.

1) it does not say that multiwire branch circuits can share the same HOT conductor
2) it is only talking about the handles of the breakers, not doubling up circuits on a conductor
3) How the HECK are you suppose to do this in a 240/120V panel?????????
4) I am still tired of hearing exceptions like these being used to facilitate your point of view, instead of abiding by what the code rule states
5) when did we throw common sense and basic electro magnetic theory OUT THE WINDOW?


Iwire, that device that you show is NOT for a 'shared' conductor circuit. That device would be wired with 2 seperate circuits (240V and 120V). AND since they are on the same YOKE, they would need to be 'handle-tied' together, BUT they are not considered to a multiwire branch circuit.(unless you were in a 3phase delta service)


I am sorry for 'yelling' through this post, but this is a big wiring mistake that needs to be avoided. My stong tone is because of the seriousness of this, and also the ease in which everyone else just accepted what they wanted, and not which was real.

 

[iwire]

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

Steve all I can say is your mistaken.

I ask respectfully again what is the electrical hazard you see with feeding the receptacle I show with one two pole breaker.


Exceptions are just as valid as 'normal' code section.

 

[peter d]

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

Originally posted by milwaukeesteve:
1) it does not say that multiwire branch circuits can share the same HOT conductor

Steve, that is pecisely the point. If the NEC does not forbid something, then it is allowed. Nowhere does the NEC actually have a rule forbidding this application.

 

[roger]

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

Steve,

Originally posted by milwaukeesteve:
Iwire, that device that you show is NOT for a 'shared' conductor circuit. That device would be wired with 2 seperate circuits (240V and 120V). AND since they are on the same YOKE, they would need to be 'handle-tied' together, BUT they are not considered to a multiwire branch circuit.(unless you were in a 3phase delta service)

if that were true why does this device,

come with a factory supplied jumper between the two devices?

Factory wording;

Easily accessed break-off, line-contact connecting tab for fast, easy split-circuit wiring.

You can read all the information by going to This Pass and Seymore page, then #1 click on "Products" "#2 "Residential Contractors" #3 "Straight Blade Devices" #4 "Hard Use Specification Grade Receptacles" #5 "Combination Duplex Receptacles".

This device is obviously made to be used on one MWBC.

Roger

[ July 04, 2005, 02:11 PM: Message edited by: roger ]

 

[iwire]

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

Originally posted by milwaukeesteve:
3) How the HECK are you suppose to do this in a 240/120V panel?????????

After reading this by you I am starting to wonder if we are talking about the same thing?

The connections on the panel end are standard multiwire branch circuit connections.

Assuming a 3 wire cable, one 2 pole common trip breaker with black on one pole red on the other pole.

White on the neutral bar, bare on grounding bar.

Now at the other end of the cable a 120 volt outlet using black and white and a 240 volt outlet using black and red.

What is the hazard that you see in that the rest of us do not?

[ July 04, 2005, 06:23 PM: Message edited by: iwire ]

 

[milwaukeesteve]

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

Again, we are talking about multiwire branch circuits. Multiwire branch circuits are multiple ungrounded conductors sharing a common neutral. (Since opposing phases will cancel each other on the returning neutral). Multiwire branch circuits do NOT mean that you can share a hot conductor between two different circuits.
The problem is that you are using equipment that is not listed for use. You would be trying to protect (OCP) a single phase 120V circuit with a double pole breaker. Not listed for use, and definitely not workmanlike manner.

Rong111 had stated an example of a 9 amp pump and a 9 amp sump pump. Now why would you do this? The circuit is going to trip whenever they both run.

My point also in my last post is that we use the exceptions to fit our point of view, instead of us following the NEC's point of view.
The NEC does not explain to us the basics of Electrical Theory. We as installers and inspectors are suppose to know that and use that knowledge along with the code rules. (This was also my hangup with the thread on parallel conductors we had just a bit ago)

 

[iwire]

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

Steve the circuit I pictured above is both safe and NEC compliant.

Originally posted by milwaukeesteve:
My point also in my last post is that we use the exceptions to fit our point of view, instead of us following the NEC's point of view.
The NEC does not explain to us the basics of Electrical Theory. We as installers and inspectors are suppose to know that and use that knowledge along with the code rules.

You as an inspector are supposed to enforce the code as written including the exceptions if you agree with them or not is not relevant.

We as installers are not 'cheating' or 'twisting' the code when we make use of exceptions.

Think on this one, the branch circuit to an electric range or dryer would be a violation if not for the exception to 210.4(C).

Take a cruise over to article 100 and look at the definition of multiwire branch circuit and you will see that the 240/120 branch circuit to a range or dryer is a multiwire branch circuit.

 

[jim dungar]

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

Multi-pole breakers are tested for interruption of single pole currents.

 

[milwaukeesteve]

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

Jim, you are not helping me in this one.

Iwire, your 'definition' that you pointed out does describe what is a multiwire branch circuit (or a network). HOWEVER, the circuit(s) you are describing, is NOT a multiwire branch circuit. A MBC contains one or more hots that share a neutral.
You cannot share a phase or ungrounded conductor between 2 different circuits, UNLESS it is a manufactured item* that is UL listed, or listed elswhere in the NEC for specific items.

* manufactured items include: stove, oven, dryer, hot tub, cooktop....

 

[don_resqcapt19]

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

Steve,

You cannot share a phase or ungrounded conductor between 2 different circuits ...

Code section?
Don

 

[milwaukeesteve]

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

Where is the common sense?
Why would you even think of doing this in someone's home?
Think of the nightmare you'd have explaining that to a homeowner when he installs a larger sump pump and the circuit trips at the start of a rainstorm, and his basement floods.
Think of the nightmare of explaining how and why, when the A/C doesn't work, and it's 100 deg 4th of July weekend, with a houseful of guests, because someone plugged a bugzapper into the service outlet, because you forgot to run 120V out to the A/C for servicing. (could happen the way some people are talking)

What happened to basic electric theory?
Did we forget our principles in wiring?
What happened to workmanlike manner which includes when we plan ahead? We should have known to bring out both 240V and 120V IF it was needed. If it wasn't needed originally, then find an alternative means, don't try and fudge the NEC or good electrical practice.

Iwire, you talk about what the harm is, and also what the difference is between this and a dryer or a range.
The difference is that the dryer has fixed components with no variables. The light on the inside isn't suddenly going to change. Yet, when you have something like this well pump/sump pump thing, there are variables that can change. That is where the safety and/or nuisance tripping or other potential hazards can happen.

 

[milwaukeesteve]

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

sorry don, missed your reply.
I don't have a code reference. That is something that should be common sense to someone that understands the basic principles of electricity.
I hate the attitude that because something isn't addressed in the NEC, we can do it. Or better yet 'if it doesn't say I can't do it, than I can do it'.
That kind of attitude takes it too far.
I am going to go 85 mph through a school zone on my way home tonight, because the NEC doesn't address it and it doesn't say I can't.