Thread: Main Breaker - 4 pole

I've seen this many times and always have the same question.
It looks like a 4 pole "tied together" main breaker, but I know the service is 120-240 volts two phase.

Why 4 breaker swithches when most main disconnects have two breaker switches (tied together)?

What is the difference between the both types?

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That's just the way the manufacturer designs a 200 amp CB, by paralleling 2-100 amp sections together.

For the record that's 1Ø, 120/240 volts not 2 phase.

That by the way is the 1st manufacturer to build them that way, there is nothing wrong w/ it, they have had almost 40 years since they came out...

BTW, the manufacturer is ITE, now Siemens, GE, Goverment Electric, & Cutler-Hammer, type CH all in one panels used them too.

It's a 150A service. Does that mean that there are 2-75A breakers?
I've never seen a 75A breaker?

Originally Posted by Ken Amelin

It's a 150A service. Does that mean that there are 2-75A breakers?
I've never seen a 75A breaker?

No it's a factory constructed, 150 amp circuit breaker.

Originally Posted by Robert Meier

No it's a factory constructed, 150 amp circuit breaker.

I'm confused. In your other post, you said they were additive.

Originally Posted by Ken Amelin

I know the service is 120-240 volts two phase.

Why 4 breaker swithches when most main disconnects have two breaker switches (tied together)?

What is the difference between the both types?

This is actually split-phase. The "phases" will be 180 degrees out. Actual two-phase would be 90 degrees out from each other. Two phase derived from three phases from, say, a normally configured commercial service would have 120 degrees of separation. I would make that call (split-phase) on your situation based on the main being on the meter box in the photo.

It's a normal residential service, but just an older style main service configuration. Two 75-amp breakers in parallel (same bus) will provide 150 amps of protection for that bus.

Two of the breakers are in parallel with each other for each of the busses, so instead of the normal one breaker for each buss, there are two. It was a way to use lower current capacity breakers for the mains...each sharing part of the load in parallel to "make up" a higher capacity breaker.

You can see the gang between the breakers in the attached photo. (Which is a photo of an overheated panel, by the way.)

Originally Posted by cuba_pete

It's a normal residential service, but just an older style main service configuration. Two 75-amp breakers in parallel (same bus) will provide 150 amps of protection for that bus.

Two of the breakers are in parallel with each other for each of the busses, so instead of the normal one breaker for each buss, there are two. It was a way to use lower current capacity breakers for the mains...each sharing part of the load in parallel to "make up" a higher capacity breaker.

OK., but now you have really confused me.

If I understand you correctly. This panel has two separate bus bars, each carrying a load of 75A. It sounds like each bus is protected by 2 breakers in parallel and these two breakers share the load of that bus.

Does that mean that each of those breakers in parallel are rated for 37-1/2A each?? (somehow that doesn't sound right???)

Originally Posted by Ken Amelin

OK., but now you have really confused me.

If I understand you correctly. This panel has two separate bus bars, each carrying a load of 75A. It sounds like each bus is protected by 2 breakers in parallel and these two breakers share the load of that bus.

Does that mean that each of those breakers in parallel are rated for 37-1/2A each?? (somehow that doesn't sound right???)

In this configuration there would be 4-75 amp single pole units connected in two pairs to give you 150 amps. IMO you shouldn't get hung up on how the manufacturer made this 2-pole, 150 amp CB only that it's a 150 amp CB.

Originally Posted by Ken Amelin

OK., but now you have really confused me.

My apologies for the confusion. The service is rated for 150A if those are 75A breakers. I cannot see the ratings in the photo...too fuzzy.

The assembly should have a rating stamped on it. It does look a little rusty though, so it may be illegible.

Originally Posted by Robert Meier

In this configuration there would be 4-75 amp single pole units connected in two pairs to give you 150 amps. IMO you shouldn't get hung up on how the manufacturer made this 2-pole, 150 amp CB only that it's a 150 amp CB.

I was trying to head off any confusion, but I guess I made it worse. I wanted to provide the basis for the conclusion to preclude further questions. That didn't work.

Can't read the amperage, but plug-on C/Bs are usually limited to a maximum of 60 amps per plug on buss connection. To safely get more than 60 amps in one C/B some mfgs. just use more connections spots, ( two connection spots per phase / leg x two phases / legs = four spaces used ).

Originally Posted by Garry Blankenship

Can't read the amperage, but plug-on C/Bs are usually limited to a maximum of 60 amps per plug on buss connection. To safely get more than 60 amps in one C/B some mfgs. just use more connections spots, ( two connection spots per phase / leg x two phases / legs = four spaces used ).

How do you explain 70, 80,90,100,110,125A breakers? There is only one phase in a single phase panel, so "leg" would be a better discription than "phase".

Originally Posted by Rollie Meyers

How do you explain 70, 80,90,100,110,125A breakers? There is only one phase in a single phase panel, so "leg" would be a better discription than "phase".

I have seen larger breakers such as those listed.

This is where a lot of semantics comes into play, what people know, what people are taught, etc., etc., etc.

There are two busses in the average residential panel...true...but they are not "in-phase" so really are therefore two distinct phases 180 degrees out from each other...but...they originate from the same winding of a single phase transformer. Therefore, some insist that this is still single phase power. However, any (AC) power that provides multiple power paths (busses) that deliver signals out of phase with each other could be considered multiple phase, but the derivation of that power is where some technicians and engineers make their definition..the original single winding. The two busses are additive when used for 240, so the single phase transformer could really be defined as a single buss of 240 split in two...split phase.

We would be able to do the same for the average commercial panel providing a "true" three phase power, where each phase is derived from its own winding. This is normally the wye side of a transformer (to give a neutral).

We could also center tap each of those three phases to give us six phases, each 60 degrees out from its derived source. It wouldn't have much practical use, though, so its not common. There would be six busses in that panel...what a mess that would be.

I digress...

Originally Posted by cuba_pete

I have seen larger breakers such as those listed.

This is where a lot of semantics comes into play, what people know, what people are taught, etc., etc., etc.

There are two busses in the average residential panel...true...but they are not "in-phase" so really are therefore two distinct phases 180 degrees out from each other...but...they originate from the same winding of a single phase transformer. Therefore, some insist that this is still single phase power. However, any (AC) power that provides multiple power paths (busses) that deliver signals out of phase with each other could be considered multiple phase, but the derivation of that power is where some technicians and engineers make their definition..the original single winding. The two busses are additive when used for 240, so the single phase transformer could really be defined as a single buss of 240 split in two...split phase.

We would be able to do the same for the average commercial panel providing a "true" three phase power, where each phase is derived from its own winding. This is normally the wye side of a transformer (to give a neutral).

We could also center tap each of those three phases to give us six phases, each 60 degrees out from its derived source. It wouldn't have much practical use, though, so its not common. There would be six busses in that panel...what a mess that would be.

I digress...

Bull puckey.

A standard resi panel is a 120/240 volt split phase panel. The two busses are merely opposite ends of the same phase and the neutral is the center point. Two phase is an entirely separate, and obsolete, type of wiring. If what you propose was true there would be no reason to supply 3 phase power or a market for phase converters - it would all be done by "phase shifting" with transformers.

I've had my fill this week already of home inspectors trying to write their own electrical code rules and now appear to have someone rewriting the rules of physics and electricity.

Pray tell, how can a single circuit be out of phase with itself?.

Originally Posted by Bill Kriegh

Bull puckey.

A standard resi panel is a 120/240 volt split phase panel. The two busses are merely opposite ends of the same phase and the neutral is the center point. Two phase is an entirely separate, and obsolete, type of wiring. If what you propose was true there would be no reason to supply 3 phase power or a market for phase converters - it would all be done by "phase shifting" with transformers.

I've had my fill this week already of home inspectors trying to write their own electrical code rules and now appear to have someone rewriting the rules of physics and electricity.

Pray tell, how can a single circuit be out of phase with itself?.

Wow...well...I don't disagree with you. I think we just are explaining the same thing two different ways. I totally agree...split phase power all from the same winding...180 degrees out of phase between the "phases"...what you described as center tapped with a neutral. I think I covered that in my post. I have no problem there.

My descriptions are worded in a way to stay out of semantical arguments with people who insist on calling traditional residential panels "two phase". Without being technically accurate, I understand what they are saying.

Two phase obsolete...yep...totally agree...as a distribution method.

No single circuit is out of phase with itself...? I don't get that question.

I am not a home inspector, but I do work with trade and non-trade inspectors on the commercial and government side (respectively).

I apologize for giving you your fill...that is not my intention.

Originally Posted by cuba_pete

Wow...well...I don't disagree with you. I think we just are explaining the same thing two different ways. I totally agree...split phase power all from the same winding...180 degrees out of phase between the "phases"...what you described as center tapped with a neutral. I think I covered that in my post. I have no problem there.

My descriptions are worded in a way to stay out of semantical arguments with people who insist on calling traditional residential panels "two phase". Without being technically accurate, I understand what they are saying.

Two phase obsolete...yep...totally agree...as a distribution method.

No single circuit is out of phase with itself...? I don't get that question.

I am not a home inspector, but I do work with trade and non-trade inspectors on the commercial and government side (respectively).

I apologize for giving you your fill...that is not my intention.

OK. Perhaps I misunderstood what you were trying to get across. I just refuse to give credence to folks who can't get it through their head that if you start with single phase that's all you're ever gonna have unless you apply a little "magic" to the the situation - like in the form of some sort of converter

Originally Posted by Bill Kriegh

OK. Perhaps I misunderstood what you were trying to get across. I just refuse to give credence to folks who can't get it through their head that if you start with single phase that's all you're ever gonna have unless you apply a little "magic" to the the situation - like in the form of some sort of converter

I agree.

Originally Posted by Rollie Meyers

How do you explain 70, 80,90,100,110,125A breakers? There is only one phase in a single phase panel, so "leg" would be a better discription than "phase".

Not all inspectors know the technical difference between leg and phase so I use both leg and phase interchangebly to help all. You have more electrical depth and did not seem to be confused by what I said. 120/240 single phase is a difficult concept to understand, unless you have more depth in the trade. Yes there are mfgs that make a 125/2 that occupys only two normal spaces, but in the case of residences these are load centers, not panel boards; an important difference in quality. A 125/2 push on C/B w/ that minimal surface contact space is unsafe and buying trouble IMHO. So how much current is a safe amount for two spring loaded surfaces about 1/4' square ? Especially after the heat from higher loads has taken the tension out of the springs and compromised those connections ? Responsible mfgs limit how much current they will allow with these contact points. The better the mfg, the lower the amperage thay allow w/ load center C/Bs. This OP example is 75 amps per set of jaws/springs/contact surfaces. The U/L label is important and a bench mark of safety, but we live in a country where money can buy anything. You will find that it is easier to get a 125/2 that will be compatible, than to get one that is U/L listed by the mgf for use in that panel. It is a mfg game. U/L tests to prove they can handle 125 amps going through them, but not U/L listed for just any load center.

Originally Posted by Garry Blankenship

Not all inspectors know the technical difference between leg and phase so I use both leg and phase interchangebly to help all. You have more electrical depth and did not seem to be confused by what I said. 120/240 single phase is a difficult concept to understand, unless you have more depth in the trade. Yes there are mfgs that make a 125/2 that occupys only two normal spaces, but in the case of residences these are load centers, not panel boards; an important difference in quality. A 125/2 push on C/B w/ that minimal surface contact space is unsafe and buying trouble IMHO. So how much current is a safe amount for two spring loaded surfaces about 1/4' square ? Especially after the heat from higher loads has taken the tension out of the springs and compromised those connections ? Responsible mfgs limit how much current they will allow with these contact points. The better the mfg, the lower the amperage thay allow w/ load center C/Bs. This OP example is 75 amps per set of jaws/springs/contact surfaces. The U/L label is important and a bench mark of safety, but we live in a country where money can buy anything. You will find that it is easier to get a 125/2 that will be compatible, than to get one that is U/L listed by the mgf for use in that panel. It is a mfg game. U/L tests to prove they can handle 125 amps going through them, but not U/L listed for just any load center.

I'd be applying the "opinions are like arm pits - everybody has a couple and a lot of them smell" to the blurb on panels and how the better the quality the smaller the branch breaker allowed.

Copper buss bar capacity is usually tentatively figured at 1000 AMPs per sq inch giving roughly 250 AMPs per Sq quarter inch, aluminum is about 70% of this. Push on breakers have two points of contact, one on each side of the buss bar tab the breaker contact pushes on to.

The connections normally don't heat excessively. Improperly torqued connections are usually responsible for overheating and are very often the cause of breaker failure and buss damage. The same thing will happen to a screw on breaker. And, the damage will happen with smaller breakers - it usually just takes longer.

Finally, most "panel board" busses are typically designed for higher current than a load center, typically 400 - 600 AMP, because they are generally expected to see multiple high current breakers installed. I'm not sure how this makes a load center an inferior product. There's no reason to install this much overkill on 99% of the residences and small commercial electrical systems.

I sleep just fine at night when I've installed a 125 AMP push on breaker on a buss listed for it.

All that said, there are some brands and vintages of equipment that should have jerked off the market and recalled.

Originally Posted by Bill Kriegh

Copper buss bar capacity is usually tentatively figured at 1000 AMPs per sq inch giving roughly 250 AMPs per Sq quarter inch, aluminum is about 70% of this. Push on breakers have two points of contact, one on each side of the buss bar tab the breaker contact pushes on to.

The connections normally don't heat excessively. Improperly torqued connections are usually responsible for overheating and are very often the cause of breaker failure and buss damage. The same thing will happen to a screw on breaker. And, the damage will happen with smaller breakers - it usually just takes longer.

Finally, most "panel board" busses are typically designed for higher current than a load center, typically 400 - 600 AMP, because they are generally expected to see multiple high current breakers installed. I'm not sure how this makes a load center an inferior product. There's no reason to install this much overkill on 99% of the residences and small commercial electrical systems.

I sleep just fine at night when I've installed a 125 AMP push on breaker on a buss listed for it.

All that said, there are some brands and vintages of equipment that should have jerked off the market and recalled.

I would not argue that panelboard construction is necessary for residential use. I do maintain 125 amps it too much for a load center C/B, using only two normal spaces.

Your buss bar conductivity analogy has nothing to do the situation / formula / equation. The panel buss bars are adequately sized for their labeled ampacity. It is the contact surface area on the plug on C/Bs that matters and that is not anywhere near the 250 amps you incorrectly imply. Big difference between how much a 1/4" x 1/4" copper buss bar will handle and how much a 1/4" x 1/4" surface area contact can handle on an aluminum alloy buss bar piece. In this case two surfaces/jaws, so call it 1/4" x 1/2" total. We are being too generous w/ the 1/4" x 1/4" assumptions brcause the C/B jaws are curved. Panel board construction is unquestonably higher quality than load center construction. You can call them good and better, if that helps, as long as it is understood that panel board construction is the "better". The reason load centers are not used in higher amperages as you again incorrectly imply, is the weakness of the load center circuit breaker contact points that we are debating. Load center C/Bs simply do not carry enough current for higher amperages and cannot be used for higher amperages. The way they accomplish higher amperages with load center C/Bs is to use more breaker landing spots. In the case of the OP two 75 amp connections on "leg" A and two 75 amp connections on "leg" B, adding up to the 150 amp total they needed. If this is not true, why is that 150 amp C/B taking up so much space ? Can you show me a 150 amp C/B that takes only two normal size spaces ? If not, why not ? Then tell me a 125/2 using only two spaces is no cause for concern. Amen on some bad manufacturers. Imagine that 125/2 being made by Zinsco.

IMO we shouldn't be using the term load center. Load center is the equivalent of calling NM cable Romex. The proper terms are cabinet and panelboard. The cabinet is the box that the panelboard is mounted in, the panelboard is the rest of the interior, including the bus, breakers, rails etc. Just my 2 cents.

Originally Posted by Robert Meier

IMO we shouldn't be using the term load center. Load center is the equivalent of calling NM cable Romex. The proper terms are cabinet and panelboard. The cabinet is the box that the panelboard is mounted in, the panelboard is the rest of the interior, including the bus, breakers, rails etc. Just my 2 cents.

The manufacturers I use calls a resi panel with push on breakers a load center. So do I.

Originally Posted by Bill Kriegh

The manufacturers I use calls a resi panel with push on breakers a load center. So do I.

Sorry R.M., but I totally agree w/ this. "panel board" construction means a significantly different standard than load center. Panel boards have dead fronts, ( basically two covers ), the C/Bs are bolted on, not pushed on and the covers have a built in lip that allows them to rest in place w/o screws or having to hold them up. Probably more differences, but you'll have to Google of call a mfg. rep. to learn the rest.

Originally Posted by Garry Blankenship

Sorry R.M., but I totally agree w/ this. "panel board" construction means a significantly different standard than load center. Panel boards have dead fronts, ( basically two covers ), the C/Bs are bolted on, not pushed on and the covers have a built in lip that allows them to rest in place w/o screws or having to hold them up. Probably more differences, but you'll have to Google of call a mfg. rep. to learn the rest.

I'm only going by the NEC definitions of the two parts, cabinet and panelboard and the NEC does not agree with your definition. Load center is a trade name and IMO is confusing since it's not defined in the NEC. I'm just expressing an opinion. As I said earlier, using the term load center in a report is like calling NM cable Romex.

Originally Posted by Garry Blankenship

Panel boards have dead fronts, ( basically two covers ), the C/Bs are bolted on, not pushed on and the covers have a built in lip that allows them to rest in place w/o screws or having to hold them up.

Nope.

- Panelboard. A single panel or group of panel units designed for assembly in the form of a single panel, including buses and automatic overcurrent devices, and equipped with or without switches for the control of light, heat, or power circuits; designed to be placed in a cabinet or cutout box placed in or against a wall, partition, or other support; and accessible only from the front.

The panelboard is the typical interior of a distribution panel/loadcenter and which is mounted in an enclosure. Both the panelboard and the enclosure are typically referred to as panelboard, distribution panels, etc.

A panelboard can accept bolt on or push on breakers, and it does have a dead front - 1 dead front. Most, if not all, also have a cover which covers the breaker handles, but the cover is not a 'second' dead front. Well, there is an exception which allows a panelboard to not have a dead front, but that is a seldom seen exception for most.

A loadcenter is listed as a panelboard, but as a product a loadcenter is a lighter duty / lower cost product, most w/ the exception of the now obsolete Pushmatics are plug-in, panelboards can be ordered w/ plug-in or bolt-on breakers. The now obsolete Cutler-Hammer PB panelboard would accept plug-in or bolt on breakers (CH & CHB type) & SQ D still sells a panelboard that accepts QO or QOB breakers. (BTW,SQ D also has a 480Y/277V panelboard that also accepts plug-in or bolt-on breakers but as a whole, a panelboard is outside the " normal" scope of a HI).

I prefer a panelboard over a loadcenter just because the cans are avail. w/ or w/o knockouts, as punching my own KO's is more useful, no twin breakers, more gutter space, but all that does come at a higher cost, just my opinion....

Originally Posted by Jerry Peck

Nope.

- Panelboard. A single panel or group of panel units designed for assembly in the form of a single panel, including buses and automatic overcurrent devices, and equipped with or without switches for the control of light, heat, or power circuits; designed to be placed in a cabinet or cutout box placed in or against a wall, partition, or other support; and accessible only from the front.

The panelboard is the typical interior of a distribution panel/loadcenter and which is mounted in an enclosure. Both the panelboard and the enclosure are typically referred to as panelboard, distribution panels, etc.

A panelboard can accept bolt on or push on breakers, and it does have a dead front - 1 dead front. Most, if not all, also have a cover which covers the breaker handles, but the cover is not a 'second' dead front. Well, there is an exception which allows a panelboard to not have a dead front, but that is a seldom seen exception for most.

I do not totally understand the "Nope" part. There are industry nuances and vocabulary that cannot be found in cut and paste code books. If you order a "panel" of the amperage and C/B capacity you desire from an electrical distributor or mfg. their first question will be "Load Center or Panel Board". The word Load Center does not exist in NEC definitions; yet suppliers and manufacturers will make that distinction before any other. In addition to differences already posted load centers have smaller gage metal and generally are significantly different in quality when compared to panel board construction. If you can put push-on C/Bs in a industry recognized "panel Board" I have never seen it. There are exceptions like Square D "I-Line" and a Cutler Hammer comparable that do push in, but are then bolted into position. I did not mean to imply two dead fronts, but belive I said it was like two covers. On a panel board when you remove the cover, a dead front or smaller "cover" still remains and surrounds the business part of the panel.

Originally Posted by Garry Blankenship

I do not totally understand the "Nope" part.

Originally Posted by Garry Blankenship

... "panel board" construction means a significantly different standard than load center.

Nope: (see below)

Originally Posted by Rollie Meyers

A loadcenter is listed as a panelboard, ...

Originally Posted by Garry Blankenship

Panel boards have dead fronts, ( basically two covers ), ...

Nope: (see below)

Originally Posted by Garry Blankenship

I did not mean to imply two dead fronts, but belive I said it was like two covers.

Nope - one is a dead front and one is a cover, i.e., not like two dead fronts and not like two covers either.

Originally Posted by Garry Blankenship

... the C/Bs are bolted on, not pushed on

Nope: (see below)

Originally Posted by Rollie Meyers

A loadcenter is listed as a panelboard, but as a product a loadcenter is a lighter duty / lower cost product, most w/ the exception of the now obsolete Pushmatics are plug-in, panelboards can be ordered w/ plug-in or bolt-on breakers. The now obsolete Cutler-Hammer PB panelboard would accept plug-in or bolt on breakers (CH & CHB type) & SQ D still sells a panelboard that accepts QO or QOB breakers. (BTW,SQ D also has a 480Y/277V panelboard that also accepts plug-in or bolt-on breakers but as a whole, a panelboard is outside the " normal" scope of a HI).

Does that clarify the "Nope." for you?

There were too many incorrect statements in your post to want to point each one out as I did above, and for which Rollie had already provided posts for some of them.

Does that clarify the "Nope." for you?

[/quote]

Nope

Originally Posted by Ken Amelin

I've seen this many times and always have the same question.
It looks like a 4 pole "tied together" main breaker, but I know the service is 120-240 volts two phase.

Why 4 breaker swithches when most main disconnects have two breaker switches (tied together)?

What is the difference between the both types?

Can u replace a 4 pole breaker with a 2 pole breaker

Originally Posted by Scottepstein

Can u replace a 4 pole breaker with a 2 pole breaker

The answer would be no-----unless the manufacturer makes a "standard" 2 pole breaker listed to be used as a service disconnect/main breaker in the panel in question.

There are most likely hundreds of thousands or more of these "4 ganged" breakers installed around the country and they work at least as well as their more common looking cousins.