Panel Question

[Casey Patten]

Yesterday I saw a double tapped 15A breaker, with the double running out of the box to the door bell transformer.  I'm calling it out on the basis of the double tap.  Thoughts?
Also, main panel is rated 125A, main disconnect is a double handled 100A, but the SE wiring is 2 AWG aluminum, rated at 100A.  I'm calling that as 100A service, but with the problem of a 200A main disconnect (too large a breaker, won't trip).  Just looking for a little feedback.
Off the the Twins game this afternoon; kids should have fun! 

[Dominic Maricic]

Have fun at the game

[John Adrian Sopher]

Do you have pics of the main disconnect?  I could be misunderstanding you, but it sounds like your describing a 100A main disconnect and calling it incorrectly as a 200 A disconnect.

[Casey Patten]

Here's a pic of the panel.  You can see the main disconnect at the upper left of the breakers.  Did I goof and call it out incorrectly?  I haven't sent the report yet (client requested that I not cash his check till Tues.  Uh huh...    )

[Michael Merino]

If the SE cables are 2 AWG aluminum then that is what you use to determine the Amps. The AWG, panel and breaker should all match, but if they don't then SE cable is the default. The breakers in this panel are 100 amp the SE cable is 100 amp. The breakers are 100 amp per leg, you do not add them together. The panel is rated higher than 100 Amp, so I think it is OK.

The double tap is a good call unless the breaker is made to accept a double tap.

[Michael Merino]

I wouldn't' release the report until the check clears.

[John Adrian Sopher]

Yes Mike has it right.  I had a feeling you were adding both sides of the breaker together.  This is a 100A main disconnect.  And you are right to call out the double tap.

Here is some helpful info from Nachi electrical course.

Determining Available Home Service

The correct way to determine the available amperage is to determine the ampacity of the lowest rated of the following components

Service supply
Electric meter & socket
Service entrance conductors
Service disconnect
Distribution panel

Here are a couple of examples:
A 200 amp service lateral, a 200 amp meter and base, a 175 amp rated SEC, a 150 amp rated panel, and a 125 amp service disconnect. = A 125 amp reportable service supply.
A 150 amp service drop, a 60 amp meter and base, a 150 amp SEC, a 100 amp rated panel, and a 100 amp service disconnect. = A 60 amp reportable service supply.

[Michael Merino]

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.

[Jeffrey Wicklander]

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.

If you are talking about 2/0 coming into a panel with a 100 amp disconnect, there is no way that this is considered unsafe.

Jeff

[Michael Merino]

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.

If you are talking about 2/0 coming into a panel with a 100 amp disconnect, there is no way that this is considered unsafe.

Jeff

Yeah, I had that backwards, If the breaker amp is larger than the SEC amp then it is unsafe. Thanks for the correction.

[Casey Patten]

Ok; confession time, I assumed (and made an a** of myself in the process) that a properly connected double 100A breaker was equivalent to a 200A breaker.  My big time error, thanks for the correction. 
I had to strain and darn near stick my nose into the box to see that the SE wires were 2AWG Aluminum...but it is there, so I was going to call it out as 100A regardless because of the "weakest link" in the panel, breaker, SE wire chain. 
The breaker I was also calling out, since it's just a 15A breaker.  Yes they did put the transformer outside the box, but the fact that it was double tapped just wasn't right. 
And finally...I still have the check and report in hand...if he doesn't want it cashed till Tuesday, fine.  I actually called his bank to confirm the account was legit.
Michael:  As much as I hate the Dirty, Hated South Siders...I have to say "THANK YOU" from the Twins! 

[Michael Merino]

No problem Casey, even us dirty hated southsiders can figure out an electric panel!! LOL 

[Casey Patten]

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

[Bill Warner]

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.

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

[Bill Warner]

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.

[John Adrian Sopher]

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.

[Bill Warner]

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.

[John Adrian Sopher]

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

[Casey Patten]

Agreed; I use the lowest rated of the service entrance, panel, main disconnect...and the meter as an indication.  BUT in this case, the meter looked to be a 200A rated box, but on the side was stamped "100A".  Interesting things...learning every day!

[Bill Warner]

Around here they have been updating the meters to much higher rated ones even though the meter can indicates the original rating.

Used to be a round can indicated 60 amp service, square was 100 amp, small rectangular was ~150 and large rectangular was 200.  I find the small circular cans all the time with updated 200amp meters installed.