It's alwas better to install the 200 amp then the 100.You may not need the 200 right now , but down the line should you deceid to change it would cost you more.
NEC 310.16 #3 Thhn Copper
No, amperage is not additive, but a constant. Think of power as water, its always the same temperature, hot (amps). The pressure is variable (volts). The true answer is undoubtedly more complex, but you get the point. If you need to draw 200 amps you would actually need a 400 amp service because code states you cannot have more than an 80% load on a breaker That's an interesting question and I had to run the theory through my brain a few times to confirm my answer. The answer is if you have a 100A 240V service, you could draw what appears to be 200A from that panel at 120V. If you install 100A 120V single pole breakers on each side of the panel (in reality this would be many breakers but let's keep it simple) then both breakers will operate just fine, giving the appearance of 200A. In reality, however, one breaker actually feeds through to the other breaker. The neutral only carries the unbalanced load so in this hypothetical situation the neutral at the panel carries 0A. So the answer to the question is...if you install ONLY 120v single pole breakers, you can run up to 200A on those circuits (or 80% of that as we have discussed.) But you are only running 100A on each leg of the service conductors and breaker.
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In copper 2/0 (2 Ought)
250 mcm
If it was preinstalled, it may have been adequate at the time of installation. It depends on the power requirements of the home. If this is a new install, the NEC has a minimum of 100A for service equipment. To be honest, I would install 200A minimum to allow for future expansion.
In my experience it is best to upgrade to an 200 amp service. The cost difference is minimal and is a selling point for the future. This includes replacing the service cable and Meter Box.
4 gauge AWG copper minimum. Use this:http://www.electrician.com/vd_calculator.htmlI found this invaluable when wiring our outbuildings. This one puts out the wire size:http://www.alternate-energy.net/voltlosscalc03.html
A #3 copper wire insulation rating of 90 degree is rated at 105 amps.
A #1 aluminum wire with a insulation factor of 90 degrees C is rated at 105 amps. Three #1 wires can be installed into an 1 1/2" conduit.
The meter is typically installed in the main circuit panel of the house. If you want to move it, you can do it as part of a service / panel upgrade. We did this when we moved into our new house - we replaced the 1950s vintage main circuit panel and 100A service with a newer 200A panel and service. It was about a grand, but we didn't actually move the panel from where it was, so it may cost more for what you want.
A 15000 KW transformer will power a small city! One KW is one thousand watts, so 15000 KW is 15,000,000 watts. The average 2500 ft2 house in the US uses somewhere between 24000 and 48000 watts maximum (thats a 100A or 200A service). Did you perhaps mean 15000 watts? That would correspond to a 60A service, which is pretty small. If you have gas appliances (stove, furnace, water heater, clothes dryer) and no big electrical appliances, such as an air conditioner, then maybe a 60A service would do. Most jurisdictions require a minimum 100A service these days except in unusual situations, such as mobile homes and such. A house that size should have a 200A 42 circuit panel. This relates to a 50Kva transformer