Amperage available

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Michaelmechanic said:
How do you know how much amperage is available on the utility's wires to a house? For an upgrade of service
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It is really nothing to worry about assuming you are notifying the power company about the up grade which I bet is required by the power company's terms of service that the customer has to agree to.

In my area a utility is supposed to be involved with a service upgrade so it is up to them to upgrade the conductors if they think it is needed. They are unlikely to upgrade.

I once rewired a 30 unit, 5 story apartment building. When we started every unit had one 14 AWG circuit running to it with 30 amp fuses supplied by a 100 or 200 amp 3 phase service. When we were done it had an 800 amp 3 phase service and 60 amp feeders to each unit.

The power company did not change the underground wire. When I asked them about it they said something that made a ton of sense. What load did I add to the service? In truth the connected load would be the same. The power company knew what this building should take to run and the NECs load calculations have nothing to do with it.
 
iwire said:
It is really nothing to worry about assuming you are notifying the power company about the up grade which I bet is required by the power company's terms of service that the customer has to agree to.

In my area a utility is supposed to be involved with a service upgrade so it is up to them to upgrade the conductors if they think it is needed. They are unlikely to upgrade.

I once rewired a 30 unit, 5 story apartment building. When we started every unit had one 14 AWG circuit running to it with 30 amp fuses supplied by a 100 or 200 amp 3 phase service. When we were done it had an 800 amp 3 phase service and 60 amp feeders to each unit.

The power company did not change the underground wire. When I asked them about it they said something that made a ton of sense. What load did I add to the service? In truth the connected load would be the same. The power company knew what this building should take to run and the NECs load calculations have nothing to do with it.
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That is hard for most people to put their heads around. Read the green.
 
Doing an addition on the house and my main being a 100a . I want to go to 150a or 200a. Why would the utility need to be notified if their wire was already sufficient. And all I wanted to know was how do u know how to tell how much is available
 
Out in my neck of the woods it is a requirement to contact the utility.
How else is the lock ring to be removed?
 
Michaelmechanic said:
Doing an addition on the house and my main being a 100a . I want to go to 150a or 200a. Why would the utility need to be notified if their wire was already sufficient.
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:huh::huh:

How would the power company know if their wire was already sufficient if they are not notified?

What I am getting at is it is not up to you to decide or figure out if it is sufficient, it is up to them.
 
Michaelmechanic said:
I was just curious if there was a way to figure out how many amps was available
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Power company folks can often tell you at a glance but keep in mind they live in a different world from folks dealing with the NEC.
How much water can you get from a water line ? Depends on the size of the pipe, the pressure supplying the pipe and how many other spigots are open. Same general idea.. how big is their wire, how big is the transformer and how much load is on it other than yours.
POCO folks play that game all day. Best to let them do the dealing.
 
Michaelmechanic said:
I was just curious if there was a way to figure out how many amps was available
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Available? Depending on conditions, there might be 1000 amps available, but not for very long :lol:. You could trace the service conductors back to the transformer and see how big that is.

As others have said, electric service is usually a "tell us what you think you need and we'll put in what we think you need".

(z remembers the back and forth with PEPCo about refurb-ing a 1923 theater... going from maybe a 400a 3phase service to IIRC a 2000a one. Fortunately, I was not the one doing the load letters on this.)
 
zbang said:
Available? Depending on conditions, there might be 1000 amps available, but not for very long :lol:. You could trace the service conductors back to the transformer and see how big that is.

As others have said, electric service is usually a "tell us what you think you need and we'll put in what we think you need".

(z remembers the back and forth with PEPCo about refurb-ing a 1923 theater... going from maybe a 400a 3phase service to IIRC a 2000a one. Fortunately, I was not the one doing the load letters on this.)
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Theater - the world I work in - has very high power requirements compared to the square footage of the building. Tungsten-halogen stage lighting can draw hundreds of thousands of watts in a typical venue. Couple that with phase-angle controlled lighting dimmers that do funky things to the harmonics and neutral currents, and services can get outright huge for even a modestly sized venue. Add the need to power PA speakers, foggers and other atmospheric effects, stage automation, etc... and the load just goes up. Not often continuous loads, but very high peak loads are possible. LED lighting is helping take the edge off, as they're more efficient and produce WAY less waste heat, but still... it all adds up.

I've had a discussion with the POCO in Chicago regarding their service size a few years ago. POCO was grumpy about upgrading the transformer and service drop. The theater was grumpy about all their stage lighting dimming when the next door Polish restaurant's freezer compressor kicked in. POCO ended upgrading the transformer and drop after I explained that the warehouse had been converted into a theater space and needed the extra capacity. Good times.



SceneryDriver
 
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From a POCO perspective you can change from a 100 amp to a 200 amp main in your service equipment, but if you haven't actually added any significant amount of load, they are still supplying the same thing they did before.

The service drop or lateral that belongs to POCO is their baby. It will attempt to deliver whatever you try to load it with, if it is undersized or excessive in length you will suffer from voltage drop if you have high enough load. Hopefully the POCO will work with you to resolve that issue, but sometimes they can be reluctant to do so.
 
jxofaltrds said:
That is hard for most people to put their heads around. Read the green.
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In Florida, they size the secondaries to the NEC and the POCO has nothing to do with them. I have a job right now where the Transformer puts out a maximum of 2776 amps. The calculated load is 4250 amps. The Engineer is requiring 8 sets of 750 MCM copper to feed the customer tap box, which I pointed out to the EE was rated at only 3800 amps. They of course, said it was OK, but didn't reduce the individual secondaries in size. What a waste of money and metal.
 
Strathead said:
In Florida, they size the secondaries to the NEC and the POCO has nothing to do with them. I have a job right now where the Transformer puts out a maximum of 2776 amps. The calculated load is 4250 amps. The Engineer is requiring 8 sets of 750 MCM copper to feed the customer tap box, which I pointed out to the EE was rated at only 3800 amps. They of course, said it was OK, but didn't reduce the individual secondaries in size. What a waste of money and metal.
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I can't make a bit of sense of that. :D
 
Another POCO standpoint...usually a newer service to a house is 200A and the fees are the same for "200A or less". Older services were 100A and may well be only rated as 125A. I'd bet no utilities offer 100A anymore. But...if you have a 100A and you upsize the meter panel to 200A, or worse yet, just put a 200A breaker in a 100A panel (if it would even fit), and don't tell the POCO, then you have set yourself up for liability if something happens such as a FIRE! The only way to know the meter, service drop, transformer, etc. are rated is to let them know. Even if your load didn't increase, you will be liable for any problems and may be legally responsible as well. Why risk it?
 
Around here we do the service upgrade with a permit from the town and don't tell the POCO unless we're moving the service, the drop, need a lock removed, etc. After the local inspection the EI sends a cut-in card to the POCO and then they come out to inspect, possibly change the meter and install permanent connections. If the drop requires changing they will do that too.
 
infinity said:
Around here we do the service upgrade with a permit from the town and don't tell the POCO unless we're moving the service, the drop, need a lock removed, etc. After the local inspection the EI sends a cut-in card to the POCO and then they come out to inspect, possibly change the meter and install permanent connections. If the drop requires changing they will do that too.
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That is pretty much the deal here as well.

That said I am willing to bet that the POCOs terms of service require notification of changes. But people are less likely to read those terms of service than Apple Software terms. :p
 
Strathead said:
In Florida, they size the secondaries to the NEC and the POCO has nothing to do with them. I have a job right now where the Transformer puts out a maximum of 2776 amps. The calculated load is 4250 amps. The Engineer is requiring 8 sets of 750 MCM copper to feed the customer tap box, which I pointed out to the EE was rated at only 3800 amps. They of course, said it was OK, but didn't reduce the individual secondaries in size. What a waste of money and metal.
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I'm having some trouble making sense of it as well, but I'm guessing you are saying the owner side of things needs sized per NEC and the POCO side of things is often (maybe always) smaller. The calculated load you mention of 4250 is probably NEC calculated load, and anything on owner side of service point is probably sized according to that value. POCO's will run equipment at higher limits then NEC, but one must also remember their equipment is outdoors and is not going to burn down a building if overloaded for too long. They also take other factors into consideration sometimes, like how long the maximum load will be present, how long will equipment be at a minimal load where it can cool, time of day and/or average temperature during peak demand periods as well. Overhead conductors will be smaller then underground conductors supplying an identical load, but they are in free air to dissipate some heat.

On the other hand there are POCO's around here that run 4/0 aluminum for underground conductors to all 200 amp and less services. They specify the owner/contractor bury a conduit from their pole or pedestal to meter base on the structure and they pull in conductors. If you only are going to have a 100 amp service, doesn't matter they still want 2 inch conduit because they are pulling 4/0 (for single phase service anyway), and you better have a 200 amp meter base because 4/0 doesn't work so well in a 125 amp meter base.
 
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