service upgrade required?

[niel]

ok so add about 12.5amps to the 100amps and i still see no need to go to a 200amp panel let alone a 150amp panel. a 100amp panel can easilly go 125amps and 112.5amps is still below that. let's put the speculation aside and wait to hear what the explanation is.

[crewzer]

a 100amp panel can easilly go 125amps

Not according to NEC 690.64(B)(2). Here is what the section says for commercial applications:

The sum of the ampere ratings of overcurrent devices in circuits supplying power to a busbar or conductor shall not exceed the rating of the busbar or conductor.

If a commercial installation panel / busbar rated at 100 A, and it’s supplied from the grid via a 100 A breaker, then no other power sources (i.e., PV and inverter) can be connected to the panel as a power source.

The reference NEC article includes a 120% exception for residential applications. For example, if a 100 A panel / busbar is supplied from the grid via a 100 A breaker, then another power source can be connected via a 20 A breaker.

So, the NEC limit would be 120 A on a 100 A panel / busbar for residential applications.

HTH,
Jim / crewzer

[xiphias]

This is a residential application. There is plenty of room on a new (2005) subpanel. Or some of the existing load can be moved from the main panel to the subpanel if that matters.

Will inquire tomorrow.

[xiphias]

After further review, it seems the upgrade is neither necessary nor required by code. Thanks for the insights.

[niel]

could you elaborate on who said what?

[xiphias]

The installer who said that an upgrade would be required misspoke. An upgrade is not necessary. (Technically, I think he was looking at the job site pics and/or notes of someone else's house, but was writing my proposal. He went back to the pics/notes of my job and saw that all was indeed well.)

[niel]

or, in speculation, maybe he was trying to get away with something. good news for you and i thought as much.

[xiphias]

This guy is totally above board. Excellent reputation, earned the old-fashioned way, and assiduously maintained. I'm a skeptic in general, and can say this was an honest mistake. Ever have two or three Word documents open at once? Save one file over another? Paste a bit of semi-custom boilerplate into a cover letter and forget to modify? That's what this was.

(He would also not have profited from this, as he doesn't do underground service work, nor does his regular electric sub, so he would have to have found a suitable sub.)

Some people are actually still honest.

[niel]

honesty in this day and age now that's a rarity. you going to have him do the work?

[xiphias]

still looking at the household economics. might start with SDHW and add PV later as resources permit.

This has been a useful and informative thread, and site. Thanks.