I feel like this is a stupid question, but how do I tell what my electrical service is? My main panel has a label that says it’s 150 Amps, and the main shut off breaker is 150 amps. But is it possible that the utility is sending more amps to the meter? I went out and looked at the meter, but can’t find any listing of the amps of service. There was a little label that said “200 CL” whatever that is, and also “240V”. But no amperage listing. I went to my utility bill, thinking that it might tell me what I am paying for, but it didn’t say.
The reason I ask is that I’m having problems with my panel (corroded bus bar), and need to replace it. It’s also full. All the breakers are in use, with no empty slots. In fact, a handfull of the breakers are the kind that are split in half to fit two circuits in one slot. So I would like to upgrade to a bigger box while I’m at it. I don’t know if I can do that on the existing service, or if I need to get the utility involved. We don’t actually use that much power, because most stuff runs on natural gas, so I think the panel is full because this old house isn’t wired efficiently.
My electrician can answer these questions, I’m sure, but he can’t fit me in for a couple weeks. I’d like to know what I may be getting myself into if I want to have a bigger panel with more slots.
Thanks!
Replies
What you are paying for is the amount that you actually use as indicated by the meter. (Note this is for residential. Some commercial will include peak usage and possibily mimuns or installation cost if you have seravice that is not common in that area).
And who pays for what varies around the country with different utilities.
But commonly you own the panel, meter can, mast (for overhead drops) and the wire in the mask and between the meter and panel. The electric company owns the meter and the drop cable.
The electric company does not "force" it on you. The service is rated by the weakest link (the lowest rated equipment).
The 200 CL is a 200 amp meter, AFAIK, all of them that I have seen so marked or 200 amp service.
So you should be able to replace the panel with a 200 amp and if needed replace the wire in mast and from the meter if needed. The only minor complication is the mast and conduit is too small to take the larger wire.
The power co might or might not have to up the size of their drop cable.
Even if you need to stay with 150 amps because it is impractical to upgrade you can still get a 200 amp/40 slot panel and keep the 150 disconnect. But you might also replace the 200 amp main with 150 amp to reduce any future confusion about what the service is.
Thanks!
Did I miss a discussion of what size drop? Power co's seem to be able to get by with smaller cable for the ampacity than after the meter. Our isspection dept defers to POCO up to the meter. Here Duke Power is pretty great at telling you very quickly what the max for the service is. When we added on their engineer wanted to rate me at 400 so they buried new cable and I had to buy a 400amp meter base. Probably gross overkill but I have some serious room for growth.
Edited to acknowledge the sentence on drop size, how could I miss it right there in plain site by itself? :-)
Bob
Edited 11/12/2004 1:24 pm ET by RASCONC
Capacity of overhead service lines which can redily dissipate heat is entirely different that that for lines inside walls, conduit, etc.
The key to forgiving others is to quit focusing on what they did to you, and start focusing on what God did for you. Max Lucado
Sojourners: Christians for Justice and Peace
Same same for direct burial I believe. I was pointing out just looking at wire size does not tell you if you are using the standard tables. Probably not as limited as one would guess.
As usual, all good points sir!
There is a whole separate table for Service Entrance and is not limited to underground and arial applications. It allows slightly higher currents, but I would have to compare line by line to see just how much.
That said there are a couple of other things to look at. First the Power Co is not covered by NEC. They can use most anythings.
Also the tables that are most used in home wiring are for NM-B and THHN. But there are many other types of wire (insulation) and applications.
There are some high temp wire that is rated many time what the common wires are.
You are mixing up a few different things. You are paying for energy used, not for current. Energy is measured in kWH (kilowatt-hours), current is measured in amps.
Current is the total instantaneous flow of electricity, in this case, into your house. A flow of 1 amp is actually a certain number of electrons per second. Your breaker panel is sized for 150 amp service, because the main breaker is 150 amps. If the total amount of current drawn by everything in your house exceeds 150 amps for just a fraction of a second, the main breaker will trip, protecting the panel from overheating.
The wiring provided by the power company might be sized for a larger service. If it is, you can wire your house for a larger service by simply replacing your main panel with one of larger amperage capacity. If the power company wiring is sized for just 150 amps, then you'll need that replaced too if you want to install a larger capacity service.
The meter totals up all the electricity used over a period of time and the total amount of energy is measured in kWH. That's what you are billed for. The power company cannot "jam" more power to you. What goes into your house is what all the appliances together draw as they need.
For a home on natural gas, a service sized for 150 amps is plenty large enough. I see no reason to enlarge it. The best course for you (your electrician will know for sure when he examines the system) is to install a new 150 amp panel with more breaker slots, or to reduce the number of circuits by combining some.
Between 20 and 40 circuits is all you should ever need, and a single panel will have enough slot for that many.
"If the total amount of current drawn by everything in your house exceeds 150 amps for just a fraction of a second, the main breaker will trip, protecting the panel from overheating."
Not true.
The will allow some some time for small overload. Can be several minute for a 20% overload.
For example if you have a load of 140 amps (assuming everything is balanced between both legs) say a well that draws a nominal 8 amps kicks on. But it might draw 50 amps for a couple of seconds when it starts up.
The breaker will not trip.
"The wiring provided by the power company might be sized for a larger service. If it is, you can wire your house for a larger service by simply replacing your main panel with one of larger amperage capacity. "
No, because there is service entrance wiring and the meter base that also need to be rated for the larger capacity. In some cases the power co supplies those, but in most cases the HO supplies those.
"The best course for you (your electrician will know for sure when he examines the system) is to install a new 150 amp panel with more breaker slots, or to reduce the number of circuits by combining some."
The way that the code is going more and more dedicated circuits are being used and can't be combined.
Edited 11/12/2004 4:55 pm ET by Bill Hartmann
I did not want the explanation to get too long by going into more rigorous detail, so my explanation was not comprehensive.
You are right. The time it takes for a breaker to trip depends on the amount of overcurrent. If it's many times the breaker rating the breaker will trip instantly. If the overload is small it may take a number of seconds to trip the breaker, by design. It's just for the kind of circumstances you mentioned.
I thought making the distinction you mentioned about the conductors between the meter and the panel would lengthen and confuse the explanation, thus I didn't state it. The few feet between the meter and the main panel would need to be sized for the new current. As far as a non-technical homeowner is concerned, that's part of replacing the main panel and does not involve the power company like replacing the conductors from the pole to the house would.
Circuits can be combined as long as the dedicated circuits required by code are maintained. 20 to 40 circuits are all any normal house needs.
Thanks. I wasn't sure what words to use to ask my question, and I know that the correct terms really matter.
I currently have 20 slots in my corroded main panel, and with the split breakers I think I have about 26 or so circuits. If I can get a new 40 slot panel with my existing 150 amp service, that should be enough. If I already have wiring sized for a 200 amp service then I'd love to get a 200 amp box. I guess my electrician will have to tell me. Dryer, hot water, furnace, and stove are all gas powered. Central air is the only really big power drain. So 150 Amps should be enough.
Thanks to everyone who responded!