what is the amperage for this house - InspectionNews

CHARLIE VAN FLEET · #1 (**permalink**) 10-24-2008, 02:14 PM

hey all

came across this main panel,alumuinum branch wires and double tapped neutral wires. but house is 2200 sq ft. do i read that main breaker as 50 amp or 100 amp ?
thanks
charlie

Lee Nettnin · #2 (**permalink**) 10-24-2008, 03:21 PM

I don't see a 'main breaker'. The 50 amp at the top is feeding something, probably a stove/range. the 40 (I think) amp 3rd and 4th position on the right appears to be feeding the entire bottom portion of the box. Me thinks it is a tad over loaded.

CHARLIE VAN FLEET · #3 (**permalink**) 10-24-2008, 03:26 PM

lee
that is labeled the main breaker and it is 50 amp

charlie

Jim Luttrall · #4 (**permalink**) 10-24-2008, 03:28 PM

The bottom right 240v is the lighting & outlet main. From what I can tell, it looks like a 50 amp 240 volt breaker. For the question that you did not ask but hinted at, you don't add the legs together on amperage, so 50 amps, not 100.

Jim Luttrall · #5 (**permalink**) 10-24-2008, 03:33 PM

I also count 7 handle throws to shut off the power rather than the 6 allowed.
You probably know this, but for the newbies out there, the labeled "Main" only controls the bottom half of the panel. This is called a split buss panel.

CHARLIE VAN FLEET · #6 (**permalink**) 10-24-2008, 03:42 PM

jim
thats exactly what i wanted to know, adding up that split. thats not enough juice for a 2200 sqft house, thats what i recommended-juice it up
charlie

Jim Luttrall · #7 (**permalink**) 10-24-2008, 03:47 PM

I can't see enough to tell for sure, but the 50 may be enough for the lighting/outlet mains. Only a proper load calculation will tell for sure.
But hey, just the aluminum wire is enough to call for a sparky

wayne soper · #8 (**permalink**) 10-24-2008, 03:51 PM

The amps is determined by the wire size , not the breaker size. Those wires look like 200 amp to me. Main breaker is not in that panel, was it in the meter box?

Gunnar Alquist · #9 (**permalink**) 10-24-2008, 04:13 PM

CHARLIE,

Like Wayne said (wrote?), there is no main breaker in this panel and the amperage is determined by the size of those cables. The cables that run up the two sides to the lugs at the top of the panel should be the feeder cables from the service equipment or the meter. The panel rating should be noted on the label inside the panel. The panel should be rated for not less than the rating of the feeder cables.

I do not see a grounding electrode conductor and it looks like the grounding and "neutral" conductors are connected to the same buss bar and the bonding strap looks like it is connected to the neutral terminal bar. As you no doubt already know, neutral and ground should be bonded in the service equipment and isolated everywhere else.

From what I can see in your pic, this looks like it is the service equipment panel, but there is no main breaker. Like Jim said, more than 6 breakers needs a main disconnect. This looks like it is an older panel and replacement should probably be your primary recommendation.

Markus Keller · #10 (**permalink**) 10-24-2008, 04:21 PM

Ditto what Wayne and Gunnar stated. In addition, those breakers at the bottom look like 'mini-breakers' (2 circuit breaker that fits into a single breaker slot). If so, are they allowed in that Muni? They aren't allowed by Code in some Muni's around here.

Jim Robinson · #11 (**permalink**) 10-24-2008, 04:49 PM

100 amp split buss panel, based on the #2 size incoming service wires. 100 amps may or may not be enough. I have 2400 square feet, a large hot tub and electric dryer and no trouble at all with 100 amps. However, I have no AC or electric heaters at all. The split buss wouldn't be allowed today, but that wasn't part of your question.

Ted Menelly · #12 (**permalink**) 10-24-2008, 06:16 PM

Quote:

Originally Posted by Jim Robinson

100 amp split buss panel, based on the #2 size incoming service wires. 100 amps may or may not be enough. I have 2400 square feet, a large hot tub and electric dryer and no trouble at all with 100 amps. However, I have no AC or electric heaters at all. The split buss wouldn't be allowed today, but that wasn't part of your question.

New Mexico????????

No AC??????????????

Oh my !

Jerry Peck · #13 (**permalink**) 10-24-2008, 06:19 PM

You would need to know the following:

1) The size of the service entrance conductors.

2) The rating of that panel.

The service size would the smaller of 1) or 2).

I count 5 'mains': 1-top left; 2-2nd from top left; 3-top right; 4- 2nd from top right' 5-3rd from top right, which is the main for the panel section below.

The larger problem I see is all those conductors going into one bushing/conduit going who knows how far. It they are like that for more than 24", then all of those conductor require derating, and there are a lot of conductors in there ... looks like 26-28, which means derating to 45% of their capacity. And that's NOT derating for ambient either, which is also required.

Don Norman · #14 (**permalink**) 10-27-2008, 10:19 AM

Service size is determined by looking at 3 factors in the service panel (2 in your case) and choosing the smallest of the three.

1. Size of the service entrance conductors.
2. The rating of the panel
3. The size of the main breaker in the panel if it has one. If there is no main breaker you only consider the first two listed above.

And, again, as Jerry indicated, you choose the lowest rated of the 3 (or 2 as the case may be).

Quote:

Originally Posted by Jerry Peck

You would need to know the following:

1) The size of the service entrance conductors.

2) The rating of that panel.

The service size would the smaller of 1) or 2).

I count 5 'mains': 1-top left; 2-2nd from top left; 3-top right; 4- 2nd from top right' 5-3rd from top right, which is the main for the panel section below.

The larger problem I see is all those conductors going into one bushing/conduit going who knows how far. It they are like that for more than 24", then all of those conductor require derating, and there are a lot of conductors in there ... looks like 26-28, which means derating to 45% of their capacity. And that's NOT derating for ambient either, which is also required.

Harry Rezaei · #15 (**permalink**) 10-29-2008, 09:24 AM

Hey. The Service Entrance Conductors are easily
visible in this distribution panel. They look like 3/0 but i can't verify.
3/0 = 200amps service.
Look at the sheathing(insulator) of the SE Conductors, it should tell you.

Jerry Peck · #16 (**permalink**) 10-29-2008, 12:23 PM

Quote:

Originally Posted by Harry Rezaei

Hey. The Service Entrance Conductors are easily
visible in this distribution panel. They look like 3/0 but i can't verify.
3/0 = 200amps service.
Look at the sheathing(insulator) of the SE Conductors, it should tell you.

3/0 = 225 amps for dwelling unit service entrance conductors

Nonetheless, though, regardless how large the service entrance conductors are, if the panel is rated less than the SEC, then the SEC rating *is not* the rating of the service.

The lowest rating is the rating of the previously mentioned items (main disconnect/SEC/service equipment) is the rating of service.

Harry Rezaei · #17 (**permalink**) 11-02-2008, 02:47 PM

Quote:

Originally Posted by Jerry Peck

3/0 = 225 amps for dwelling unit service entrance conductors

Nonetheless, though, regardless how large the service entrance conductors are, if the panel is rated less than the SEC, then the SEC rating *is not* the rating of the service.

The lowest rating is the rating of the previously mentioned items (main disconnect/SEC/service equipment) is the rating of service.

There are cases when the Panel is rated less than
the SEC in which, the true problem is that the Panel is undersized, for reasons such as new Systems/Equipments added (Central A/C, Electric Heat) etc., without replacement of the panel.

This can overheat the panel, and ultimately cause a fire. The panel should always be equal to, or higher-rated than the SEC and the Main Breaker/Fuses.

All in all, the SEC is the most reliable source in determining the service size.

Matt Fellman · #18 (**permalink**) 11-02-2008, 03:53 PM

The 240 volt breaker that controlls the lower portion of the panel is usually labeled the 'sub main' - Whenever I see the 'main' sticker on it I just assume the installing electrician just grabbed the wrong sticker.

Jerry Peck · #19 (**permalink**) 11-02-2008, 05:27 PM

Quote:

Originally Posted by Harry Rezaei

There are cases when the Panel is rated less than
the SEC in which, the true problem is that the Panel is undersized,

Absolutely incorrect.

The panel is sized for the load, or as required for other reasons.

The service entrance conductors must be as large as the panel rating *IF* the full panel rating is to be used.

Now, consider these two options (the first will address why you are incorrect):

1) The full panel rating is needed, the service entrance conductors are sized for that same rating, then, *the service entrance conductors are sizes larger to accommodate voltage drop. Now, the service entrance conductors *ARE THE CORRECT SIZE* ... and in which the panel *IS THE CORRECT SIZE* ... which means "There are cases when the Panel is rated less than the SEC in which, the true problem is that the Panel is undersized," is an incorrect statement.

Quote:

This can overheat the panel, and ultimately cause a fire. The panel should always be equal to, or higher-rated than the SEC and the Main Breaker/Fuses.

Totally incorrect. See the above.

*AS LONG AS* the mains can protect the service entrance conductors within their rating, and *AS LONG AS* the panel is protected by the main with its rating ... ALL IS FINE.

Thus, if ... IF ... *IF* ... all is sized properly, the Main Disconnect rating will govern. But, as we all know ... if ... IF ... *IF* ... that's a lot of "IFs" to have be all correct.

Quote:

All in all, the SEC is the most reliable source in determining the service size.

Again, absolutely not.

For the reasons given above.

2) The service entrance conductors are sized for the load, the panel is sized larger, for one of many reason which do not affect this, and the main is sized for the load (which matches the service entrance conductor rating).

Nothing wrong with that.

Not only are you severely limiting yourself if you try to rely on the size of the SEC for determining the rating of the service, but you are also going to be wrong many times, quite possibly wrong most of the time.

Jerry Peck · #20 (**permalink**) 11-02-2008, 05:32 PM

Quote:

Originally Posted by Matt Fellman

The 240 volt breaker that controlls the lower portion of the panel is usually labeled the 'sub main' - Whenever I see the 'main' sticker on it I just assume the installing electrician just grabbed the wrong sticker.

Matt,

That's the right sticker.

It designates that is the breaker which is serving as "the main" for the sub-fed panel at the other end of those feeders coming off that breaker.

When one panel feeds another panel which feeds another panel which feeds another panel, each breaker feeding the sub-fed panel services as the "line side main" for the sub-fed panel.

In the case of a split-bus panel, it becomes "the main" for the lower panel section. That "main" plus the other "mains" in the top panel section must number fewer than 6 total combined.

Ted Menelly · #21 (**permalink**) 11-02-2008, 07:37 PM

Hmmmm

So, if they are sub-fed panels then they must be Sub-panels. Or sub panels. Or something for a submarine. Or are there sub panels in a home?????

Jerry Peck · #22 (**permalink**) 11-02-2008, 08:54 PM

Quote:

Originally Posted by Ted Menelly

Hmmmm

So, if they are sub-fed panels then they must be Sub-panels. Or sub panels. Or something for a submarine. Or are there sub panels in a home?????

Unless you are in a submarine, they are not sub panels.

They are "panels" which happen to be sub-fed from another panel.

And, while you have brought it up, and we are on this point, *ALL PANELS* are wired the same, with the neutral isolated from ground.

In the "service equipment" the neutral would be bonded to ground.

The logical next question is: What if there is a panel "within the same enclosure as the service equipment?", and the answer is "You have already answered your question by referring to it as service equipment. You do know that the neutral gets bonded to ground in the service equipment, right?"

Subpanels? Never have seen one yet. Never toured a submarine either.

Wait, I have seen panels in sub shops, so, are those "subpanels"? Hmmm ... interesting question ...

but, how does that affect the way they are wired? It does not.

They are "panels".

Ted Menelly · #23 (**permalink**) 11-02-2008, 09:12 PM

Quote:

Originally Posted by Jerry Peck

Unless you are in a submarine, they are not sub panels.

They are "panels" which happen to be sub-fed from another panel.

And, while you have brought it up, and we are on this point, *ALL PANELS* are wired the same, with the neutral isolated from ground.

In the "service equipment" the neutral would be bonded to ground.

The logical next question is: What if there is a panel "within the same enclosure as the service equipment?", and the answer is "You have already answered your question by referring to it as service equipment. You do know that the neutral gets bonded to ground in the service equipment, right?"

Subpanels? Never have seen one yet. Never toured a submarine either.

Wait, I have seen panels in sub shops, so, are those "subpanels"? Hmmm ... interesting question ...

but, how does that affect the way they are wired? It does not.

They are "panels".

Well I do like subs and I do go to sub shops and they do have electric panels in them so I guess they are sub panels. I new they existed some where. Thanks for clearing it up for me

Richard Hedrick · #24 (**permalink**) 11-03-2008, 01:32 PM

Ok Jerry... although I sometimes grow weary of the incessant posturing that occurs on this board I am amazed and delighted at the amount of useful information and guidance provided on the forum. I would like to thank everyone for the thoughtful information.

Now because I have been in a submarine I thought I would supply all of you with with a picture the only valid subpanel that I know of .

Jerry Peck · #25 (**permalink**) 11-03-2008, 05:14 PM

Quote:

Originally Posted by Richard Hedrick

Now because I have been in a submarine I thought I would supply all of you with with a picture the only valid subpanel that I know of .

Richard,

Thank you for the photo of a subpanel, I hope you do not mind that I have saved it to my computer for future subpanel discussions.

Thanks!

William Brady · #26 (**permalink**) 11-03-2008, 05:21 PM

New Mexico OH my you say. Ever heard about swamp coolers??? Los Alamos, Santa Fe, and Northern NM cool and high in altitude makes for a very nice climate. Just defending one of my own.

Richard Hedrick · #27 (**permalink**) 11-03-2008, 10:11 PM

You bet Jerry... Ill look forward to that !