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I hired an electrician to do some work on my house and he said that they did a check with the city and there was no permit for 100amp service issued so I must be on 60amp. I think this may be a load of hooey as I have a main breaker box that is relatively new which has the old 60amp box on a sub.

Is there a way I can tell visually if I have 100amp service or if I am on 60 amp? Will my power provider know this?

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If you have a 100 amp breaker, but only 60 amp feeder wires from the transformer, there is a possibility that you could short out and blow the whole transformer -- leading to civil penalties. (Usually you will just give yourself "glow-fault" induced brownouts that damage equipment on your property.) ... If it was the movies, then you would melt the feeder wires and drop energized 220V onto a sidewalk full of preschool kids. :) –  Brock Adams Apr 21 '12 at 2:32

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Having a certain level of "service" entails that the required level is supported all the way from transformer to panel. Just because you have a new panel does not necessarily mean anything about the type or size of service you have.

For example, someone could install a panel with a 100amp breaker even though the service was only designed for 60amp.

The only way to know for sure is to verify with the electrical company what your location is permitted to run based on the last permit and inspection. If the gear in your house has changed illegally, after the electrical company reports back you should have an electrician ensure everything else is up to code and able to support that load.

The maximum service you can have is dependent on:

  1. The capacity of the transformer feeding your house
  2. The wire gauge used between the transformer and your house
  3. The size of the electrical meter box (it has to safely support the conductor size)
  4. The maximum load supported by the meter
  5. The wire gauge used between the meter and your main circuit breaker
  6. The maximum load supported by your main circuit breaker and load center.
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I would suggest checking with the power company. I don't know how old your house is but unless it is really old, I can't see them using wire sizes other than what would fit 100 - 125 amp and 200 - 225 amp on normal housing. If your house was made in the 50's or earlier might be a different story.

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Wires good for only 60 amps were commonly used for houses right up until the 60's (at least out west). If your house has (or once had) a fuse box at the main, then chances are the feed from the pole is only good for 60 amps (#6 or even #8 wire). –  Brock Adams Apr 21 '12 at 2:38

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