Electrical Service Rating - HELP!

[Tom Cissell]

After my first few inspections I am struggling with trying to determine the rating of the electrical system. The panel I get as well as the disconnect which so far have all been in the panel.

1. I had an AEP guy tell me that the shape of the meter box (round = 60 amps, square = 100, and rectangular = 150 or 200) isn't an indicator of the rating of the meter. Yet I have not seen any other visible indications on the meters to tell me what the rating is.

2. So far, all the electrical services have been lateral and the cables do not have any labeling on them as to size or rating. I doubt that anyone would recommend that I take a caliper to them inside the box.

How do experienced inspectors deal with this?

[Nick Ostrowski]

I typically identify the size of the service cable (60, 100, 150 or 200 amps) by the visual width of it. After seeing many cables, you get a feel for what the size of the cable is by just looking at it. Many cables have no legible labeling on them either. I also have a service cable guide for 60, 100, 150, and 200 amp cables printed on the backside of my business cards so if I have doubts, I can hold a card up to the width of the cable for comparison. I have seen copper service cables which run thinner than aluminum service cables so they can throw off visual estimations.

This can throw a wrench in the works but sometimes a house can have a 200 amp service cable entering the meter box and service panel but only a 100 amp main disconnect inside the service panel. In this case, the house really only has 100 amp service.

[Tom Cissell]

That's a good tip. If I can find a store that carries these cables I can take my calipers and develop a figure of merit.

[Nick Ostrowski]

If you'd like, I can mail you one of my business cards. It has the lines already measured out and pretty accurate on the back side. Shoot me a PM with your address if you're interested.

[Steven Turetsky]

Tom,

It's always the weakest (lowest rated) point that determines the size of the service rating.

Look at the panel rating first, then compare the main breaker to the panel. If the main breaker is more than the panel is rated for it is bad (less is ok). If the breaker is "more" than the SECs it is also bad. Don't forget to check if the distribution wires are compatible to the breakers protecting them.

[Speedy Petey]

Too many people, DIY and H-I alike, concentrate on the meter itself. The glass meter itself is of absolutely NO consequence. It means nothing and has NO bearing on your inspection, even if you or anyone else consider it to be completely "wrong" or otherwise. They are owned, maintained and replaced by the POCO and only at their discretion.

About the only thing that would be cause for alarm is if it is physically broken or smashed.

[Speedy Petey]

That's a good tip. If I can find a store that carries these cables I can take my calipers and develop a figure of merit.Not at all accurate. Different cables and insulations types will wreak havoc on this philosophy.

[Tom Cissell]

Speedy Petey,

I understand your point but how do you determine the rating of the cables?

[Speedy Petey]

Speedy Petey,

I understand your point but how do you determine the rating of the cables?By finding out the size of the conductor itself.

[Tom Cissell]

OK. How do you do that? Do you observe it where it terminates in a lug on the panel and just know from sight? Do you take a caliper to it? OR?

[Steven Turetsky]

OK. How do you do that? Do you observe it where it terminates in a lug on the panel and just know from sight? Do you take a caliper to it? OR?

I don't know who sells them these days, but I used to have a set of plastic tabs (gauges) with cut outs to fit (and measure) the cables.

I don't
recommend sticking a METAL calliper in there... it may be an electrifying and memorable experience.

The tabs are slimmer than a caliper too, so it may fit better.

If you can't get the tabs, get some short samples of cable and compare the conductor(s). as Pete stated, it's the conductors that matter and not the thickness of the insulation.

Be careful.

[Speedy Petey]

Those plastic gauges would be nice. Barring that, either read the lettering on the cable or familiarize yourself with typical service cables and go by eye. Barring that, simply state you cannot determine the size of the service cable so you cannot determine the service size, this might not look so good though.

It's funny, I don't think I can ever recall a complete service done with undersized wire. I personally don't think this is that much of an issue.
Things to look out for are panel changes/upgrades without replacing the entire service. That is where things can get dicey.

[Garry Blankenship]

Assuming you have only one main panel, the best determination of service capacity is the supply conductor size. Being lucky enough to visually see a label is maybe a 50/50 proposition; even when you know what to look for. Insulation type and thickness can make it even more difficult. Find a real wire size chart at a Lowes, Home Depot or electrical distributor and take time to really look and compare the wire sizes & insulations. Guessing wire size/ampacity even after that remains imperfect, but it helps. If there is a ledgible permit, it should state service size. The amp rating of the equipment can also help, but it too is not a sure thing. If you have a single main breaker / service disconnect, that could be your service size - - - assuming the supply conductors were correctly sized. There really is no bullit proof way around being able to visually size the supply wires and know their ampacity.

[Tom Cissell]

Thanks for all the tips and suggestions guys.

[Steven Turetsky]

Assuming you have only one main panel, the best determination of service capacity is the supply conductor size. Being lucky enough to visually see a label is maybe a 50/50 proposition; even when you know what to look for. Insulation type and thickness can make it even more difficult. Find a real wire size chart at a Lowes, Home Depot or electrical distributor and take time to really look and compare the wire sizes & insulations. Guessing wire size/ampacity even after that remains imperfect, but it helps. If there is a ledgible permit, it should state service size. The amp rating of the equipment can also help, but it too is not a sure thing. If you have a single main breaker / service disconnect, that could be your service size - - - assuming the supply conductors were correctly sized. There really is no bullit proof way around being able to visually size the supply wires and know their ampacity.

The only way I know to rate a service is by looking at all of the variables (sec, panel, main breaker); whatever component has the lesser rating is what the service is rated for.

If you had 2/0 cu sec but a main breaker rated at 150 amps, would the service be rated at 200 amps? No. The service would be rated at 150 amps.

There would be a problem if it were the other way around. Lets say the sec is 1-cu, which is rated at 150 amps and the main breaker is rated at 200 amps. The service would still be rated at 150 amps, but there would be a safety issue because the main would allow more amperage to be drawn through the sec than it is rated for.

[John Kogel]

Forget the round meter base myth. A round meter base is simply old. The service could be 100 amps, 60 or something else.

Be sure your report says "estimated" service size.

At some point you will find a service with no main breaker, just 3 conductors screwed into a panel. :D

[Lon Henderson]

Wow! Once again, I am amazed to learn that something that doesn't seem to be that big an issue garners so much commentary. I don't mention service wire gauge size unless I see an obvious problem.

On the extremely rare occasions that I have, I simple state something like, "service conductor size appears inadequate for service requirements, have a licensed electrician evaluate"......

Maybe you guys have more problems with this in other parts of the country than we do around here, but this seems to be another one of those items where you can make it tougher than it really has to be.

[Steven Turetsky]

Wow! Once again, I am amazed to learn that something that doesn't seem to be that big an issue garners so much commentary. I don't mention service wire gauge size unless I see an obvious problem.

On the extremely rare occasions that I have, I simple state something like, "service conductor size appears inadequate for service requirements, have a licensed electrician evaluate"......

Maybe you guys have more problems with this in other parts of the country than we do around here, but this seems to be another one of those items where you can make it tougher than it really has to be.

I'm surprised to hear that you think the electrical system is no big issue, and that you only mention something that is a problem. What does it say in your electrical section if you find nothing wrong?

Amongst other things, I always mention wire size including the size of the breaker that is protecting it.

"service conductor size appears inadequate for service requirements" can you explain this?

[Nick Ostrowski]

Proper identification of the service rating is definitely a significant issue. If your report states the house has 200 amp service but it turns out the house only has 100 amps, that could have a significant economic impact on the buyers if they want to make some electrical upgrades only to find out they need a bump up in service.

[Speedy Petey]

I'm surprised to hear that you think the electrical system is no big issue,I HARDLY think that is what he is saying.



..... and that you only mention something that is a problem. What does it say in your electrical section if you find nothing wrong?WHY should it say anything???
"Electrical system: No defects found."

Or are you one of those that HAS to find something wrong in every area of an inspection? :rolleyes:

[Steven Turetsky]

I HARDLY think that is what he is saying.


Wow! Once again, I am amazed to learn that something that doesn't seem to be that big an issue garners so much commentary. I don't mention service wire gauge size unless I see an obvious problem.

This thread was started by an inspector asking how to rate an electrical service. That is a very good question by an inspector trying to do a thorough job. When you do a home inspection (or an electrical service/system inspection) don't you tell your clients the size of the service in the home?

I do.

I provide a complete description of the entire service/distribution (within accessibility). I also include how/extent that the system (outlets) was (were) tested. If appropriate, I will state that no defects were noted. But I still include a description.




Service:

The electrical service to this home is rated at 100 amps 120/240 volts and is protected by circuit breakers. The system is equipped with a cold water ground. The General Electric breaker panel (rated at 125 amps) is located in the front of the basement and consists of a 100 amp main breaker. The service feeds are 2 awg aluminum cables. The electric meter is located on the outside of the home adjacent to the circuit breaker panel. The service feeds, weather head, service drop, and drip loop appear adequate/serviceable.

Distribution:

The distribution wiring in the home is copper. Approx 70% of the wiring is original cloth insulated wire. This inspection did not notice any brittle or burned wires. The remainder of the distribution wire has been upgraded to newer/modern type pvc insulated. There is 12 gauge wire protected by 20 amp circuit breakers. There are 14 gauge wire protected by 15 amp breakers.

Outlets:

During this inspection where accessible, a representative number of outlets were tested and it was noted:

Some of the outlets are equipped with two prong outlets. These outlets are not grounded and could be a hazard.
Various outlets are wired wrong (reversed polarity)
This inspection was unable to locate any outlets in the dining room.
The outlet in the 2nd floor bathroom is not GFI protected, and should be upgraded.
The outlet provided at the washing machine/dryer is not GFI protected, and should be upgraded.
There are various missing outlet covers.
This inspection did not note any exterior outlets.
Kitchen countertop should have additional outlets.

I recommend that a qualified/licensed electrician evaluate the entire system and make necessary upgrades.

I don't believe this thread has run on too long either (although that may now change).


WHY should it say anything???
"Electrical system: No defects found."

You gotta be kidding! You don't even tell a client what size service they have? You don't tell them if there is Cu or Al? You don't tell them if the GFIs/AFCIs functioned? etc, etc, etc.

Please tell me you're kidding. You're kidding, right?


Or are you one of those that HAS to find something wrong in every area of an inspection? :rolleyes:

No I am not. Are you one of those guys that only reports defects?

Not only do I report defects, I also report [certain] good/correct things too.


Speedy, there are two things I don't rush; sex and home inspections.

By the way, how did you get the name SPEEDY?

[Lon Henderson]

I'm surprised to hear that you think the electrical system is no big issue, and that you only mention something that is a problem.
Ok, confession time.........I confess that I have been involved on this website and in enough threads to know that I would stir somebody's pot with my comments. Nevertheless, I am dismayed at your observation abilities, if you somehow thought that I was saying that the electrical system is no big issue. If your state's SoP requires you to note service conductor gauge, well, that settles it for you.

I don't comment on service conductor size unless there is a problem with it. And I wonder why you would if not required in your SoP. I don't comment that Breaker #4 is a 20 amp breaker with 12 gauge wire connected to it either. But if it has a 14 gauge wire to it.....it gets written up. I make any notations about the panel and service that may be of interest to a client in their normal use of the home, i.e., "you need to prune that dead limb above the service conductors, or this is the main breaker, or this breaker controls all the 120v breakers, or this is a GFCI breaker and this is how it looks when it trips and this is how to reset it.....".

But it is the rare client who gives two cents about the service conductor size, unless I tell him/her that it is wrong.

[Speedy Petey]

You gotta be kidding! You don't even tell a client what size service they have? You don't tell them if there is Cu or Al? You don't tell them if the GFIs/AFCIs functioned? etc, etc, etc.

Please tell me you're kidding. You're kidding, right?I NEVER said you shouldn't give a description. I was ONLY talking about defects.




No I am not. Are you one of those guys that only reports defects?I don't report anything, unless of course someone calls me to do an electrical evaluation.




Speedy, there are two things I don't rush; sex and home inspections. TMI!!




By the way, how did you get the name SPEEDY?It all began with racing cars and motorcycles.

[Jerry Peck]

For any inspector who feels that electrical is not as important as some other systems - think of this:
- when a roof leaks ... what happens? Things get wet.
- when plumbing leaks ... what happens? Thing get wet.
- windows, doors, and exterior walls leak ... what happens? Things get wet.
- when electrical systems leak ... what happens? PEOPLE DIE.

[Garry Blankenship]

The only way I know to rate a service is by looking at all of the variables (sec, panel, main breaker); whatever component has the lesser rating is what the service is rated for.

If you had 2/0 cu sec but a main breaker rated at 150 amps, would the service be rated at 200 amps? No. The service would be rated at 150 amps.

There would be a problem if it were the other way around. Lets say the sec is 1-cu, which is rated at 150 amps and the main breaker is rated at 200 amps. The service would still be rated at 150 amps, but there would be a safety issue because the main would allow more amperage to be drawn through the sec than it is rated for.

I'm with you in spirit, I believe, but do not fully agree w/ your deduction. 2/0 cu is allowable as a 200 amp residential service rating. Just because there is only one disconnect, ( you used 150 amps, but it could as easily be 100 amps or less ), I would not necessarily call it a 150 amp service, ( though I might ). In jurisdictions that allow more than one main disconnect it is legally possible to have two 150 amp MCB panels on that 2/0 cu wire. It is the calculated load and the service entrance conductors correctly sized to that calculated load that determine service size; not necessarily the size of the MCB / s. Just like the branch breakers in a panel often total more than the panel MCB rating, the main disconnect amperage ratings added together can exceed the SEC size.

[Garry Sorrells]

Tom,
Go to an electrical supply house and get 6"or 8" pieces of all of their service cables. Then throw them into your gadget bag to use as a comparison in the field. Soon you will not need to use them for most jobs and you have a comparison reference library when you are stumped. You also could make your own plastic gauge set from the cable you have. The big box stores carry service cable but not a verity in both AL and CU.

[Tom Cissell]

Thanks Garry S. I will do.

[Garry Blankenship]

Are you referring to something like you would see in a two family dwelling?

No. It is reaching a bit to make a point, but possible. Similar to a 320 amp meter feeding two 200 amp MCB panels in a single residence. Since I said two 150 amp MCB panels could legally supplied by one set of 2/0 cu, there would have to be a bussed gutter, gutter w/ split bolts or a landing pad between the meter and the two panels. The point was that the SEC capacity is the best determinate in indenifying service size. Two 150/2 MCB panels would imply a 300 amp service when the 2/0 SECs would be more accurate, ( 200 amp service )

[Kristi Silber]

After my first few inspections I am struggling with trying to determine the rating of the electrical system. The panel I get as well as the disconnect which so far have all been in the panel.

1. I had an AEP guy tell me that the shape of the meter box (round = 60 amps, square = 100, and rectangular = 150 or 200) isn't an indicator of the rating of the meter. Yet I have not seen any other visible indications on the meters to tell me what the rating is.



Often modern meter bases will have CL200 stamped or written on them, indicating potential 200 A service. I've seen this on a round meter base. I've also seen a few obviously older round meter bases I suspect are 60 A, coupled with 100 A panels. Although it's sometimes hard to make any solid conclusions about meter amperage, I still think it's worth looking at.



Too many people, DIY and H-I alike, concentrate on the meter itself. The glass meter itself is of absolutely NO consequence. It means nothing and has NO bearing on your inspection, even if you or anyone else consider it to be completely "wrong" or otherwise. They are owned, maintained and replaced by the POCO and only at their discretion.

About the only thing that would be cause for alarm is if it is physically broken or smashed.
(Speedy Petey)

No consequence? Means nothing? The HO still should be alerted to an undersized meter, even if it doesn't mean shelling out thousands to have it updated. The POCO may own the meter, but the HO pays for the equipment (and its installation) used to mount the meter if it has to be changed. At least that's Centerpoint Energy's policy. Besides, the POCO owns the service drop, too, but that's still an issue.

Apart from amperage, how about water infiltration or evidence of tampering? Those would alarm me.

[Speedy Petey]

Often modern meter bases will have CL200 stamped or written on themThe meter itself will, not the meter pan.




No consequence? Means nothing? The HO still should be alerted to an undersized meter, even if it doesn't mean shelling out thousands to have it updated.An undersized meter? The glass meter itself???
When have you EVER seen that??



The POCO may own the meter, but the HO pays for the equipment (and its installation) used to mount the meter if it has to be changed. At least that's Centerpoint Energy's policy. Besides, the POCO owns the service drop, too, but that's still an issue. THAT is my point. The POCO owns and maintains the meter itself. ALL the other equipment is the homeowner's.



Apart from amperage, how about water infiltration or evidence of tampering? Those would alarm me.Maybe that, but that is also extremely rare. Like my last sentence implies, physical damage is a different case.

[Bill Kriegh]

I realize that folks have a job to do. And, if that job involves taking the cover off a panel to look at the goodies that's OK. But, when we start talking about gauges, presumably to be used for measuring service conductors, I get a bit concerned.

If there is any question about the size of a wire in a panel and it involves "touching" it with something, you need to be wearing insulating gloves and a face shield at minimum. Many wires have been damaged at installation or by other factors and may be just a hair's width from being in a fault situation - that you bumping it could put it in.

If the need to know what the stuff in a service will handle and is listed for goes beyond visible labels, maybe you aren't the one that needs to make the determinations. I know from personal experience just how far a faulted service entrance cable can shoot molten metal, and a lot of stuff is about eye level...............

[John Kogel]

I realize that folks have a job to do. And, if that job involves taking the cover off a panel to look at the goodies that's OK. But, when we start talking about gauges, presumably to be used for measuring service conductors, I get a bit concerned.

If there is any question about the size of a wire in a panel and it involves "touching" it with something, you need to be wearing insulating gloves and a face shield at minimum. Many wires have been damaged at installation or by other factors and may be just a hair's width from being in a fault situation - that you bumping it could put it in.

If the need to know what the stuff in a service will handle and is listed for goes beyond visible labels, maybe you aren't the one that needs to make the determinations. I know from personal experience just how far a faulted service entrance cable can shoot molten metal, and a lot of stuff is about eye level...............Thanks, Bill, good comment.

In my area, I am just barely permitted, by the provincial Safety Authority, to remove the cover. I am not permitted to "perform work" inside the panel. To me, that bars us from poking around in there. There would be no compensation for a lost eye, in other words.

Take pictures, learn to visually judge the sizes and types common to your area. Another place to see the service conductors is at the weatherhead.

[John C Hansen, LEED AP]

I scanned this very long thread, so forgive me if I have overlooked the answer, but in "Home Inspector School" we were taught to identify the size of the meter. I also saw a lot of information to enlighten me about the common (older) socket sizes. If a meter is a CL200 in an old round socket that may once have had a 60 amp meter in it, or maybe an old 100 amp box/socket, why is the box and meter so important to our training as inspectors if the wire size and main breaker are the real determinant for the Amperage capacity supplied to the house? What if the service from the electric company is smaller than the rest of the wiring from the meter socket to the main breaker? Why was there so much apparent emphasis placed on the meter and socket?

[Jerry Peck]

I scanned this very long thread, so forgive me if I have overlooked the answer, but in "Home Inspector School" we were taught to identify the size of the meter. I also saw a lot of information to enlighten me about the common (older) socket sizes. If a meter is a CL200 in an old round socket that may once have had a 60 amp meter in it, or maybe an old 100 amp box/socket, why is the box and meter so important to our training as inspectors if the wire size and main breaker are the real determinant for the Amperage capacity supplied to the house?




Because meter sockets burn up when used over their rating - I have personally inspected several dozen burned up meter sockets 9which were used over their rating) while working as AHJ electrical inspector.

The meter sockets also loose their pressure connection to the meter, complicating any condition which is even at or near maxi,um rating.

As a home inspector, seeing an old possibly 60 amp or 100 amp with a 200 amp service panel should trigger some thoughts of unpermitted work and work which is likely to have other issues.

[quote]What if the service from the electric company is smaller than the rest of the wiring from the meter socket to the main breaker?

The overhead service from the utility company will be smaller as it is in 'free air' and has better heat dissipation abilities, which means that a smaller size conductor can service the same ampacity as a larger conductor in a raceway or cable.

[John C Hansen, LEED AP]

Jerry, when you said: "Because meter sockets burn up when used over their rating" I understand and appreciate that. But in a case where I have seen only the meter was upgraded to a CL200 in an original older socket and all the rest of the wiring was left as it had been when the house was built with what we might determine is 60 amp breaker panel and service drop, the new CL200 meter is not a cause of concern, is it?

[Jerry Peck]

But in a case where I have seen only the meter was upgraded to a CL200 in an original older socket
.
.
the new CL200 meter is not a cause of concern, is it?

John,

Excellent question - maybe one of the electricians here will know if the meter prongs on the newer higher rated meters are the same size as the clips are in an old 60 amp or 100 amp meter base.

I would think ... that there would be a difference in the meter prongs from a lower rated meter to a higher rated meter, but ... maybe not.

Using the same clips in a higher rated meter socket would allow a lower rated meter to be installed in the meter socket - such as in a panel where 15 amp breakers can be installed where 100 amp breakers can be (there is a listed limit for the breaker tabs, typically 100 amp ... the same would likely be the case for meter socket clips - but what is the limit of the accepted range?).

Another answer is this:

- Even if higher rated meters "fit" into the "old" and lower rated meter socket, given that we know meter sockets wear out ... is it a good idea to reuse an old meter socket by installing even a lower rated meter in it ... much less reuse an old meter socket with a higher rated meter in it?

- Which brings us to the listing and labeling requirements of the code - are the old lower rated meter sockets listed and labeled for use with higher rated meters? Probably not.

All of the above leads to a 'Have electrical contractor verify, and document, listing and labeling rating of the old meter socket with current use of a higher rated meter.' (The "and document" part is important as it is that documentation which counts ... not 'the electrician says'.)

My guess is that the electrical contractor will say to replace the meter can as the listing and labeling in that old meter can may no longer be legible.

[John C Hansen, LEED AP]

Jerry, I am interested in this thread. When a flipper does nothing new on the electrical system and the house sat vacant for a while without a meter... then the flipper calls for service and the power company comes and pops a meter in, I would think the power company knows what they are doing.... but maybe not.

[Jerry Peck]

John,

If the shoe fits ... er ... I mean "meter" fits ... put it in.

I doubt the power company cares unless/until someone complains about the power flickering and the power company goes out and tells the occupants that they need to have a new meter can installed before power can be reconnected.

Which leaves the occupants without power.

[Jim Port]

What is causing the socket to wear out? It gets installed and typically never changes unless the house is sold and changed out. It is not a consumable.

[Jerry Peck]

What is causing the socket to wear out?

Aging, heat, and time.

The spring tension on the clips weakens, contact with the meter prongs becomes less, which leads to heating, which eventually leads to poor connection between the two, which results in fire (caused by arcing) or just burned up ends/parts which cause fluctuating voltage ... I've seen many while inspecting replacements.

Question for you: Do you know the maximum rating for the old 60 amp and 100 amp meter cans/sockets - is the maximum rating that 60 amp or 100 amp rating?

Which would indicate the acceptability of installing 200 amp meters in 60 amp meter cans/sockets?

[Jim Port]

Not sure I understand the question. Why would there be an issue with a meter that can handle up to 200 amps being installed in a lesser rated socket?

[Jerry Peck]

Not sure I understand the question. Why would there be an issue with a meter that can handle up to 200 amps being installed in a lesser rated socket?

Do the prongs match the meter socket clips?

What is the listing and labeling rating on the meter socket?

The saving grace would be (if it is) that the main service disconnect(s) has not been changed ... but what if it was, or something was re-wired to bypass the main service disconnects?

Glad that you don't seem to have a problem with it, but I have seen too many burned up meter sockets and clips to want to mis-match things and approve it. Even as an AHJ inspector with sovereign immunity (I couldn't be sued as an AHJ inspector), but you as an electrical contractor ... with just your insurance??? Depends on how you play the game, I guess.