Thread: determining panel amperage

Sorry this is such a basic, boring question, but I can't seem to find a definitive answer in my books or online. I learned in training that when two main breaker switches marked 100 are tied together, that means the panel amperage is 200. This doesn't seem right to me. Am I wrong?

And if a panel is rated for 100 amps according to its sticker, isn't having a 200 amp main breaker a hazard?

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Originally Posted by Kristi Silber

Sorry this is such a basic, boring question, but I can't seem to find a definitive answer in my books or online. I learned in training that when two main breaker switches marked 100 are tied together, that means the panel amperage is 200. This doesn't seem right to me. Am I wrong?

And if a panel is rated for 100 amps according to its sticker, isn't having a 200 amp main breaker a hazard?

Hi Kristi,

You are correct in that it is not right. You do not add up the amperage marked on 2 pole breakers (or main breakers). If the main breaker has one marking saying 100 or two markings saying 100, it is 100 amp.

Sincerely,

Corey

If the two-100 amp CB's are assembled as one unit then it's likely that the single unit is rated for 200 amps. This is common with GE breakers which seem to have 4-poles.

Regarding a 200 amp CB in a 100 amp rated bus panel, it may or may not be a problem based on a number of factors. One example of where is would not be a problem would be a 100 amp bus panel with a 200 CB fed from a 100 amp feeder. Possible but not very likely.

Originally Posted by Robert Meier

If the two-100 amp CB's are assembled as one unit then it's likely that the single unit is rated for 200 amps.

Not correct as stated, but based on your next statement you are on the correct path, so I will restate what you said to make it correct: if two double pole 100 amp breakers are assembled as one quad unit, then it is rated as 200 amps. This is because each leg of the breaker has a double pole 100 amp breaker, i.e., has 200 amps for the paired 100 amp breaker.

This is common with GE breakers which seem to have 4-poles.

Which is why I specified that you are referring to the quad breaker, and "then it is likely", because there may be some quad breakers which are not rated double as such.

Most, but not all, of those quad service disconnect breakers will be labeled with the doubled rating, i.e., a quad of 100 amp breakers may say 200 amp on the handle tie ... but it might not say that ... which is what makes this so much fun.

Oy, nothing seems to have a simple answer! I don't even know what a quad unit looks like. Have to pay more attention.

I hate to think how many times I've gotten the amp rating wrong because of my training!

a picture is worth a thousand words !

Originally Posted by Kristi Silber

Oy, nothing seems to have a simple answer! I don't even know what a quad unit looks like. Have to pay more attention.

I hate to think how many times I've gotten the amp rating wrong because of my training!

There is some information here on the connection and wiring of those quad service disconnect breakers: AskCodeMan.com - Ask Codeman Building Code Q & A

Here's the GE main breaker that I was referencing. It's a factory assembly of two 100 amp 2-pole CB's. I'm assuming that this is what was referenced in the OP.

Originally Posted by Robert Meier

Here's the GE main breaker that I was referencing. It's a factory assembly of two 100 amp 2-pole CB's. I'm assuming that this is what was referenced in the OP.

Hello All,

The photo posted by Robert is the so call quad but that doesn't matter. For all practical purposes, this is a 200 amp breaker and the marking on the handle tie says 200.

Kristi, just go by the number marked on the main breaker. Don't add them up. The most common you will probably come across is 100, 150 and 200. Some old stuff might be 60 and some new stuff might be 400. You'll know the 400 when you see it.

Each manufacturer does thier own thing and models change over time. You have now seen a picture of the "quad". You probably have seen plenty of 2 pole breaker types. Square D makes some with what looks like a large fat, thick breaker with one handle (looks like an overgrown single pole breaker but it is not). If you stick with the number marked on the breaker you should be fine. Don't worry about the other stuff.


Best to All,

Corey

Wow. That's what I thought. Blows my mind.

From my training:

"It is possible for more than one circuit breaker switch to be joined together (referred to as "married" or "coupled") and work in conjunction as the main breaker switch. If this is noted, then the amperage of these "married" switches must be added together to determine panel amperage rating." Then there's a photo of a GE quad breaker just like that, marked 200 on each switch, and they say it should be noted as an 800 amp service.

Originally Posted by Kristi Silber

From my training:

"It is possible for more than one circuit breaker switch to be joined together (referred to as "married" or "coupled") and work in conjunction as the main breaker switch. If this is noted, then the amperage of these "married" switches must be added together to determine panel amperage rating." Then there's a photo of a GE quad breaker just like that, marked 200 on each switch, and they say it should be noted as an 800 amp service.

What I think that was meaning was that the two 200 amps on one leg of the quad would be added together to 400 amp, but not add the other leg together ... I think ... that is what they meant, but that was not what was said ... so much comes down to 'how' something is said as to whether or not the statement is correct or not.

Now you've got me all confused!

For the sake of educational purposes, I think this is kosher...

Below is the photo, and here's how we handle it:

"In the example below right, 4 main breaker switches, rated at 200 amps each, are joined and work together as the main circuit breaker switch. The electrical service for this system is therefore rated at 800 amps. Field representative would select "Other" and type "800Amp-CB" for main panel amperage and protection type."

Originally Posted by Kristi Silber

Now you've got me all confused!

For the sake of educational purposes, I think this is kosher...

Below is the photo, and here's how we handle it:

"In the example below right, 4 main breaker switches, rated at 200 amps each, are joined and work together as the main circuit breaker switch. The electrical service for this system is therefore rated at 800 amps. Field representative would select "Other" and type "800Amp-CB" for main panel amperage and protection type."

That is a 400 amp main breaker.

Depending on how main breaker tabs are manufactured in the panel, there are two ways that could be configured:
1) The left two are on one bus phase and the right two are on the other bus phase, which makes each bus phase as having 400 amps overcurrent protection.
2) The outer two are on the same bus phase and the inner two are on the same bus phase, which still makes each bus phase as having 400 amps overcurrent protection.

Regardless, you do not add the four 200 amp breaker ratings together.

Hmmm, okay, I can see that. And the double pole legs of a breaker are assemblages of two on the same bus? (Those of you who don't know me well - I'm brand new to electrical stuff, learning new terminology as we speak. Well, I guess that's obvious!)

a picture is worth a thousand words !

Indeed it is! Thanks, Robert, for posting that awesome photo.

I've got another example, much less appealing. Is it true that the one marked for the subpanel acts as its mains?

Originally Posted by Kristi Silber

Now you've got me all confused!

For the sake of educational purposes, I think this is kosher...

Below is the photo, and here's how we handle it:

"In the example below right, 4 main breaker switches, rated at 200 amps each, are joined and work together as the main circuit breaker switch. The electrical service for this system is therefore rated at 800 amps. Field representative would select "Other" and type "800Amp-CB" for main panel amperage and protection type."

I agree with Jerry that's a 400 amp, likely 240 volt CB in the photo. IMO you will never see an 800 amp CB in that frame size.

Originally Posted by Kristi Silber

Is it true that the one marked for the subpanel acts as its mains?

If I am understanding your question, you are asking if the breaker to the remote panel (marked sub panel even though it is not going to a submarine panel ) acts as a main for the remote panel?

It would in that the breaker is protecting the feeders to the remote panel, and it is also protecting the remote panel at that same level of protection (the rating of the sub feed breaker). You could flip that breaker to 'off' and the remote panel is no longer powered. The main protection, though, is for the feeders going between that breaker and the remote panel, followed by protection of the main bus bars in the remote panel, which is why the panel bus needs to be rated at least the same, or greater, than the sub feed breaker protecting the remote panel.

Sorry! I forgot my "main" question - the mains on the panel shown...two parts, each marked 100, bar between with no mark...it's rated 100, right? I want to make sure I have this right.

Thanks, Jerry, that makes sense.

Originally Posted by Kristi Silber

two parts, each marked 100, bar between with no mark...it's rated 100, right?

Right.

We need to get something straight here. These "quad" breakers are, regardless of what they look like, considered a single, multi-pole breaker. They are common trip, which means the trip mechanism for all 4 sections is common, and if one of the 4 trips, they all do. You can't take the assembly apart and make separate breakers out of it.

The rating stamped on the quad unit is the rating for the entire breaker, not for half of it or a 4th of it.

The breaker in Kristi's picture (post #12) is a 200 AMP breaker. I probably install 2 or 3 a month that look just like it.

GE doesn't even list anything in a resi panel larger than 225 AMPs

Wait - which picture? Which post? #12, right?

There are 3 manufacturers that use(d) the 4 pole wide breakers, the 1st one was ITE, later Siemens, GE, & Cutler-Hammer,

Below is a example of a Cutler-Hammer type CH factory installed main, one of these days should photograph all 3 makes side by side & post it.

Originally Posted by Bill Kriegh

We need to get something straight here. These "quad" breakers are, regardless of what they look like, considered a single, multi-pole breaker. They are common trip, which means the trip mechanism for all 4 sections is common, and if one of the 4 trips, they all do. You can't take the assembly apart and make separate breakers out of it.

The rating stamped on the quad unit is the rating for the entire breaker, not for half of it or a 4th of it.

The breaker in Kristi's picture (post #12) is a 200 AMP breaker. I probably install 2 or 3 a month that look just like it.

GE doesn't even list anything in a resi panel larger than 225 AMPs

I concur

Originally Posted by Jerry Peck

That is a 400 amp main breaker.

Just thought that should be preserved for posterity

Originally Posted by Jerry Peck

That is a 400 amp main breaker.

Depending on how main breaker tabs are manufactured in the panel, there are two ways that could be configured:
1) The left two are on one bus phase and the right two are on the other bus phase, which makes each bus phase as having 400 amps overcurrent protection.
2) The outer two are on the same bus phase and the inner two are on the same bus phase, which still makes each bus phase as having 400 amps overcurrent protection.

Regardless, you do not add the four 200 amp breaker ratings together.

What are you talking about?!? The breaker is 200 amp.

Originally Posted by H.G. Watson, Sr.

What are you talking about?!? The breaker is 200 amp.

Yes I agree and retract my earlier statement.

I suggest the 800 amp reference in the training manual, is a typo. Can't tell you how many typos I've seen in training material.

I suggest the 800 amp reference in the training manual, is a typo. Can't tell you how many typos I've seen in training material.

If only that were the case! No, they just have it wrong. That's why I said it blows my mind. There have been many trainees given wrong info.

Originally Posted by H.G. Watson, Sr.

What are you talking about?!? The breaker is 200 amp.

I went back and reviewed the information from talking to various people and engineers for the companies - except GE, they never responded - and what Roger found out when he did the same - with no response from GE either - and this is what I came up with:
- Some of those 4-pole breakers are made with each breaker labeled, such as 100-100-100-100 and with the handle tie labeled 200, making a 200 amp breaker.
- Some of those 4-pole breakers are made with no label on each breaker and with the handle tie labeled, making the breaker what is labeled on the handle tie.
- Some of those 4-pole breakers are made with each breaker labeled 200-200-200-200 (as in Watson's photo above) and the handle tie not labeled, making the breaker what is labeled on each breaker, 200 amp in this case (thus in this case Watson is correct - that breaker is a 200 amp breaker).
- And with Roger finding out that the largest single pole breaker of a double pole breaker or 3- or 4-pole breaker is 125 amp, the largest 4-pole breaker would be 250 amp, which means that the 200 amp on each breaker in Watson's photo above is not that of each individual breaker, but of the completed 4-pole breaker unit.

I would say that I stand corrected, but ... I am sitting at my computer, so I sit corrected.
(Hey, we all got to fess-up when we are wrong ... er ... except for Watson, I don't recall him ever fessing-up to anything, but, that would be Watson.)

Originally Posted by Jerry Peck

I went back and reviewed the information from talking to various people and engineers for the companies - except GE, they never responded - and what Roger found out when he did the same - with no response from GE either - and this is what I came up with:
- Some of those 4-pole breakers are made with each breaker labeled, such as 100-100-100-100 and with the handle tie labeled 200, making a 200 amp breaker.
- Some of those 4-pole breakers are made with no label on each breaker and with the handle tie labeled, making the breaker what is labeled on the handle tie.
- Some of those 4-pole breakers are made with each breaker labeled 200-200-200-200 (as in Watson's photo above) and the handle tie not labeled, making the breaker what is labeled on each breaker, 200 amp in this case (thus in this case Watson is correct - that breaker is a 200 amp breaker).
- And with Roger finding out that the largest single pole breaker of a double pole breaker or 3- or 4-pole breaker is 125 amp, the largest 4-pole breaker would be 250 amp, which means that the 200 amp on each breaker in Watson's photo above is not that of each individual breaker, but of the completed 4-pole breaker unit.

I would say that I stand corrected, but ... I am sitting at my computer, so I sit corrected.
(Hey, we all got to fess-up when we are wrong ... er ... except for Watson, I don't recall him ever fessing-up to anything, but, that would be Watson.)

Neither GE, ITE (Siemens) nor Cutler Hammer or anyone else for that matter make this style breaker bigger than 225-amps

Here's a little breaker math for you! Remember this is only for a lesson in breaker math!

Question: If you take any two breakers and put them both on the same phase and hook them up in parallel (run a wire from one to the other and then out to a load) what is the total amperage they will take before tripping?

Answer: It is the combined amperage of the two breakers.

That is basically what they have done with the pictured 4-pole breakers! If you look at the line side lugs you see one-lug per phase that splits into two blades ((1) for each of the two 100-amp single poles for that phase to plug onto) then on the load side it goes back from both lugs (each single pole 100-amp) to one bus bar phase. Same for the other phase!

A breaker wired in parallel with another breaker combines their value.

The various ways of marking these breakers was probably an attempt to make it less confusing! As you can see ...that didn't work out too well for some folks.