TOPIC: Panel Question

Yeah, big help they were today!    One more game...163, Part 2...glad Thome is NOWHERE near us this year!  ;D

The safe and proper service amperage available at a property is set by the smallest of: the service conductors, the main disconnect fuse or switch, or the rated capacity of the electric panel itself.

If you're calling a house service size amperage rating based solely on the SEC, you may find yourselves in trouble with an angry client and/or insurance company seeking reimbursement for an upgrade.

Electric is one of the weakest and most misunderstood sections for all home inspectors.

www.inspect-ny.com/electric/ElecAmps3.htm

I have to disagree with this statement "The correct way to determine the available amperage is to determine the ampacity of the lowest rated of the following components". For Example if you have a 2/0 copper SEC, which is for 200 amp service, and a 100 amp panel, it is still a 200 amp service, not 100 amp. It is also unsafe, and should be reported as such. The SEC, breaker, panel, meter panel should all have matching ampacity.

As an HI, you know that a 2/0 can carry 200 amps, but you have no way to tell how much is actually coming in from the electric company, you have to assume the amps is what the SEC can safely carry. So a 200 amp SEC in a 100 amp panel can cause the panel to overheat.

This information is quite incorrect Michael and is no more unsafe than screwing in a 60amp light bulb in a fixture rated for a maximum 100amp bulb.

The method I posted was directly from NACHI electrical course.  Its also the way it was taught to me in my HI school.  I have not found any indication that it is incorrect.

You are correct John. It is based on the lowest denominator of the system, but quite often it is difficult (if not impossible) to find the rating of the meter itself.

I try to go off the meter box shape.  This can give you an idea but not always accurate.