Thread: Is this 100 amp or 200 amp service?

Ok, did my 1st home inspection Friday. Client and realtor tell me home has 100 amp service. They pass me the mls listing which says 100 amp service (which I'm pretty sure they're simply parroting).
So I'm now writing my report and reviewing my Pics taken during the inspection. I'm pretty sure I'm looking at 200 amp service. Service panel has 2-100 amp breakers bridged. But, would sure appreciate a second opinion before I tell them they're wrong.





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No question it's only 100-amp service if that is the service panel. The back-fed breaker is only feeding 100-amps per leg. So it's a 100-amp 240/120 volt service.

Wayne,

Ouch. I'll stick to the question at hand.

That is only ONE two pole 100 amp breaker. The panel itself is probably only rated for 100 or 125 Amps.

Originally Posted by neal lewis

Ouch. I'll stick to the question at hand...

I think what Neal is referring to, is that no one wants to say, Wayne, you really need more training and knowledge before doing more inspections on your own.
Well, ok, someone probably wants to...

Biting my tongue.

Wayne,

Couple of things:

As has been stated above, that is a 100 amp breaker - two poles (think of it as two 100 amp breakers side by side) but not in the way you are thinking of it.

You are thinking you add the two 100 amp rating together, you don't. Think of it as a 'U' shaped circuit with one breaker feeding each leg of the 'U' and the load (the house) being the closed end of the 'U'. That means that only 100 amps is 'flowing through' the load (the house).

When you put the photos in your post like that instead of making them links as almost all of the rest of us do, the photos cannot be seen as well as when they are attachments which can be opened, enlarged/zoomed in on.

Makes it much easier to review the photo while responding too.

If you would, repost your photo as an attachment and then we can go over it with you.

Pay no attention to the fact that it is a 200A meter supplied by the utility company. They are using the 200A meter on services at or below 200A these days. Rare to find a CL100 meter in my neck of the woods anymore.

If you are looking at a CL100 meter with a 200A service or a 200A service with a 320A continuous service then chances are the change was made without the knowledge of the utility company.

Back to the question. You are not giving enough information to make an actual determination. Wire size and type from the overhead through the meter enclosure to the main panel or disconnect is what we need.

The size and rating of the main panel is only part of the equation to determine service size. I have seen 200A panels fed by a 100A service and a 100A panel fed by a 200A service. Never know what you are going to find.

Thanks for the quick response guys. Report had not gone out and nothing was said to the client. But your all of course right, I'm obviously the new kid. I'll be diving back into my Russell Burgess before I go out again.
Sorry for the lame thread.

Wayne,

Every inspector here at InspectionNews largely "learned on the job".

And at least in my case I sometimes find I am still asking myself the occasional very basic question (for example I found myself uncertain this morning, "is "trap height" defined as "trap weir height"? - I've always assumed so, but don't know so , so I asked).

However ... yours is a VERY basic question - about as fundamental as can be asked at a home inspection - and if you have to ask it, you are likely missing very significant defects at your inspections, at your present state of knowledge you are likely putting both yourself and your clients at significant financial risk, and perhaps putting yourself at increased risk of physical injury (and even death) as well.

FWIW, my suggestions are:

1) Best choice would be to suspend doing inspections until you have more knowledge.

2) If you decide to continue inspecting, carry E&O and GL insurance from a reputable carrier. Your liability exposure is highest in the first 250 inspections and IMO if a beginning inspector cannot afford to do so, they cannot afford to be in the business.

3) Pursue every route to obtaining more knowledge.

- Before I started inspecting I had read my way systematically this and two other boards, taking notes as I read, and this was a huge help.

- Continue to expand you notes as you learn, mine are in a large MS word document - include code references (for your own knowledge, if not for reports), links to the place where you found the material, diagrams and tables, etc. . (I you would like, I will send you you a copy of mine).

- As quickly as possible take continuing education - a least one class in each major area such as plumbing, electrical, etc - at this stage in the business these will help reinforce what you learned in your licensing classes and will probably also present some basic material not covered there.

- Keep asking questions, here and elsewhere, even if some comments are less than polite.

4) Whatever else happens, when you "don't know" at an inspection, just say "I will have to research that" and then do so - fortunately (from the novice the inspector's standpoint) most clients don't know what you can be expected to know, or not.

Wayne,

In addition to the information above, and especially Jeff's post regarding the other parts of the "electrical service" after the meter, which includes the "service equipment" where the main disconnect is (in your photo, that panel is not just a "panel", it is actually the "service equipment" and that top right breaker is the "main disconnect".

Being as the "service equipment" also includes the panel, one could call it the 'service panel', however, a more accurate description would be 'service equipment panel'.

Back to what Jeff was saying: The "service size" is always the smallest of the following:
- the rating of the service entrance conductors
- the rating of the main disconnect
- the rating of the service equipment (in this case the rating of that service equipment panel)

The smallest of those will be the rating of the service, HOWEVER, the smallest of those *also must be the main disconnect*, which must be the same size as, or smaller than, the other items. The reason for this is that the main disconnect is what protects the other items from burning up in the case of an overload.

Also ... that main disconnect (the top right breaker) has the service entrance conductors (which are 'hot' *all the time*) feeding the main breaker (main disconnect), and as such, if that main breaker were removed from the panel, and accidentally left 'on' or bumped 'on', the contact on the breaker would also be 'hot' - which could surely cause a serious electrical shock, if not electrocution, should anyone touch those contacts with the breaker removed. When the main breaker is fed by the service entrance conductors, it is referred to as "back fed" (because the normal connection of a breaker is 'hot' at the panel contacts and 'switched' at the breaker terminals, meaning that the main breaker in your photo is fed backward, or "back fed").

That leads to this: When a main breaker is "back fed", the breaker is required to have an additional clamping means (usually either a clamp or an additional screw) that the panel connection ends to prevent the breaker from being removed without specifically intending to remove it.

I do not see any screw or clamp holding that back fed main breaker in place.

Wayne,

Contrary to what some of the posts above are implying, there are no 'dumb questions', no matter how basic the question may be. The only 'dumb question' is 'the question not asked' - if the question is not asked, there will not be an answer given for it ... and 'that' is dumb.

We all started out with limited knowledge, we each likely had either a specialty in construction we came from, or a general knowledge of construction we had acquired, regardless, none of us *knew much then* and those of us who know, know that we know *even less now*. That is because the more we know, the more we know we don't know.

Now, based on the above ... think how much Einstein did not know! He spent his life trying to figure things out, only to know less and less and less ...

I do not see any screw or clamp holding that back fed main breaker in place.

I believe there is one. If you look to the left of the main breaker you can just see a red "dot". ITE/Siemens uses a tricky little retaining device (ECMBR1). It's red plastic and is mostly hidden from view once installed, at least from the angle of that photo.

See.. http://www.mclendons.com/img/products/10/10455240.jpg

http://www.murrayconnect.com/NR/rdon...9/0/ECMBR1.pdf.

I don't know what else that red "dot" would be.

Richard,

It could be that, I zoomed in as much as I could and that red looked like a reflection off the bus bar, but ... it could be that.

Hey Wayne,
As everyone said, being new is nothing to be ashamed of. We all started there and we all asked questions.
Good luck and keep up with educating yourself. You worked hard to get through the Illinois requirements in order to get your home inspector license.

Michael -
Excellent advice all around, especially the bit about taking notes. That has been the key in my own training to make the information stick a little better. I also strongly recommend performing practice inspections for friends, coworkers, etc. This has been extremely helpful in exposing gaps in my education that I otherwise wouldn't have known about. Hopefully I'll be in business myself soon. Just need a catchy name...

John L. Duncan
<insert cool name here> Home Inspection Services

Originally Posted by John Duncan

... Hopefully I'll be in business myself soon. Just need a catchy name...

John L. Duncan
<insert cool name here> Home Inspection Services

Slam Duncan Home Inspections

Pretty bad, huh?

The meter is a 200 amp meter. The service panel appears to be a 100 amp box where 100 amps is your incoming service. I see smaller breakers for lighting circuits, 1 GFCI for bathrooms and a 30 amp breaker that may be for an electric water heater. If this is the only panel in the house, my guess is that all the rest of the major appliances and furnace are gas.
From this picture I can't see if there is the 4th incoming ground wire and a ground buss bar.
Because the meter is rated for 200 amps, another panel could be added if you wanted an electric stove, electric furnace, electric welder or what ever.
This looks fairly common for an older style panel but the picture doesn't show enough to see if everything is wired correctly.

Isn't there a way to total the amperage of the breakers and come to a conclusion?

Originally Posted by Ben Gardner

Isn't there a way to total the amperage of the breakers and come to a conclusion?

Adding up the breaker handles is not an accurate way to determine the service size. This would not account for any diversity factors like for heating and air conditioning that are not used at the same time. It would be common to find 7-800 amps of breaker handle rating in a 200 amp panel.

The correct method is called a demand load calculation.

Originally Posted by Ben Gardner

Isn't there a way to total the amperage of the breakers and come to a conclusion?

No. For the simple reason that you could put every single receptacle in the house on a dedicated circuit, or divide them out in any number of different ways (40 circuit panel, each with a 20 AMP breaker for a receptacle). There are code required circuits for the kitchen/dining room, bath, furnace and such that prevent putting the entire house on a single circuit but you could have a small home with a 200 AMP panel and a half dozen breakers totaling around 100 AMPs easily. Same house and circuit setup can easily be set up on a 100 AMP panel.

Another combination of stuff would be where someone had a large number of electric heater circuits and several A/C circuits. Only the largest of these two loads would be considered when sizing the service because they wouldn't both be on at the same time. With a couple or three A/C units you'd have maybe 90 AMPs of "breakers" that wouldn't even count against a 100 AMPs of breakers for heating loads.