Electrical panel upgrade

[foo1bar]

However, in that case, I would object to the suggestion that 140 A of supply on a neighbor's 125 A panel should not be surprising.

Not quite what I said.
I said that he shouldn't be too surprised if what he has is 140A for the main breakers, yet HIS panel only has 125A busbar.
ie. it's quite possible that someone overloaded that main panel sometime in the past. So don't rely on the existing 140A to come to the conclusion that the bus bar is at least that.
(at last I'm assuming those are the main breakers - that there isn't a main breaker of 100A or whatever feeding to those two since he said there's only 2.)

Since a permit and inspection are required in most locations to benefit from net metering or to add new service, and attempting to DIY a second service breaker is stupid, I would doubt many people would get away with overloading the bus. That is just too easy for the AHJ to catch.

Adding a 2nd breaker (the 40A for the AC) would be something I can easily see an A/C installer doing. Adding it would be no different skills than adding a breaker to any panel without shutting off power to the panel.
Fairly easy for the AHJ to see and catch? yes - they would need to know it's a 100A or 125A service and 125A busbar.
Would they see it and catch it? Maybe. I wouldn't bet on it though - it depends on how thorough the inspector is, how many other inspections he has to do, and whether he thinks to look at that particular item and not just look at where the AC unit is and the fuse box or disconnect that's next to the unit.

Since the OP is looking at adding solar, he needs to be sure what he has - and I'm sure that breaker box will be looked at when inspecting for solar / net-metering. But that just means it has to be fixed right before the solar install is finished - not that it was done right N years ago.

[foo1bar]

Unfortunately, you cannot use load breakers (which these are)

awhite's description makes me believe these are the main breakers for the property - ie. those two breakers do not have another breaker between them and the meter.
And therefore I don't think the right term for them is "load breakers", as they are providing the main shutoff functionality as well.

as any indication on what the panel's buswork is rated for.

I agree that you can't use them. IMO you can't really use anything except documentation for the panel.
There are many 125A busbar panels with 100A main breakers. And having recently replaced a panel with a 100A and 30A breaker but had a 125A busbar, I can easily see someone doing 140A on the same kind of panel.

[awhite]

Here's a photo of the panel

I took the cover off the panel and took a pic. it's a Siemens meter box combo, still don't know the rating...does this look familiar to anyone ? the breaker layout, etc? Thanks in advance..WP_20150218_15_19_24_Pro.jpg

[foo1bar]

I took the cover off the panel and took a pic. it's a Siemens meter box combo, still don't know the rating...does this look familiar to anyone ? the breaker layout, etc? Thanks in advance..[ATTACH=CONFIG]5857[/ATTACH]

Similar layout to the one I replaced with a Homeline SC20140M200F from HD.
(My old one was Federal Pacific not Siemens)

How has it gone with checking with the neighbor's houses?

[SunEagle]

I took the cover off the panel and took a pic. it's a Siemens meter box combo, still don't know the rating...does this look familiar to anyone ? the breaker layout, etc? Thanks in advance..[ATTACH=CONFIG]5857[/ATTACH]

First off where are the rest of the load breakers that feed you appliances and outlets?

That looks like just the main input power from the Utility transformer. That 100 amp breaker could be the Main and the 40amp is a line side tap for a sub panel.

[foo1bar]

First off where are the rest of the load breakers that feed you appliances and outlets?

That looks like just the main input power from the Utility transformer. That 100 amp breaker could be the Main and the 40amp is a line side tap for a sub panel.

What I see in the picture the 40A and 100A are connected to the same busbar. Therefore it is not a line-side tap.

The 100A and the 40A are together the shutoff for the property.
Code allows you to have up to 6 breakers.

And he's stated that the 100A feeds a subpanel.

BTW - I don't see any room for additional breakers (can't have down==on)
So I think a new panel is in awhite's future. (maybe he can do a line-side-tap and not upgrade the panel - I don't know much about those)

[sensij]

I took the cover off the panel and took a pic. it's a Siemens meter box combo, still don't know the rating...does this look familiar to anyone ? the breaker layout, etc? Thanks in advance..[ATTACH=CONFIG]5857[/ATTACH]

To answer your question... if this is the panel you intend to supply from the inverter, then yes, an upgrade is required. There is no space for the new supply line, so busbar rating doesn't matter.

If your interior subpanel has space for the additional breaker, and is accessible for a new wiring run, it might accept the inverter input without an upgrade, if its rating supports it.

[awhite]

WP_20150218_15_16_55_Pro.jpg

Here's the panel cover itself, any thoughts on why there's another cutout right above the 40A breaker? The cover was just made that way?

[foo1bar]

[ATTACH=CONFIG]5858[/ATTACH]

Here's the panel cover itself, any thoughts on why there's another cutout right above the 40A breaker? The cover was just made that way?

physically you can see that there is space for 2 more 2-pole breakers above the existing ones. HOWEVER code says that for breakers being used for shutoff of the supply, they need to be down=off/up=on. Therefore those 4 slots aren't usable for your situation.
I would guess someone first put the breakers in one over the other, and then they had to reposition them and put plates over the "oops".

[CraziFuzzy]

Derating to 80A main would be the easiest part, and in that case, wouldn't require an engineer at all. But that may not be a possibility. Technically, you can't derate the service disconnect to less that 100A.

Now, I'm not saying this is often enforced, as there are an awful lot of solar installs in my area without upgraded panels, but by the letter of the code, 100A is the smallest you can go, which means on my center-fed panel, technically I couldn't even add a single amp of power. In fact, line-side would technically be out, as I'm not sure there's a connection point between the meter and the main breaker (direct buss bar from meter socket to main breaker). About the only options, if it IS a 100A buss (still undetermined, as three neighborhood houses I've checked so far, none have a sticker), would be separately metered solar tied in before my main service meter, or panel replacement.

My guess is the local AHJ is assuming 125A busses (replaceable main breaker plus construction in the 90's probably backs that assumption up - I just hate not seeing it in writing), and that is how the other installs have been done in the neighborhood, but I haven't gotten a chance to chat up any of the neighbors with the actual solar.

I finally got around to chatting with the AHJ, and it turns out that all of the homes in my development are center fed panels with no rating stamps/stickers, and 100A feeders - but based on age (early-mid 90's) they are operating on the assumption that they are 125A busses, and allowing solar based on that. He actually alluded to the fact that they are still allowing the 120% overrating (150A supply breaker total) if the feeder is at the long end of the bus (these center feds aren't symmetrical), which I don't believe to be correct, but am not going to argue - I'm only adding 20A anyway. So, with that word, I can go ahead and submit, order, and build - which is good - am quickly running out of tolerable weather...

[inetdog]

What I see in the picture the 40A and 100A are connected to the same busbar. Therefore it is not a line-side tap.

The 100A and the 40A are together the shutoff for the property.
Code allows you to have up to 6 breakers.

And he's stated that the 100A feeds a subpanel.

BTW - I don't see any room for additional breakers (can't have down==on)
So I think a new panel is in awhite's future. (maybe he can do a line-side-tap and not upgrade the panel - I don't know much about those)

You are correct in your analysis, but marginal on your use of the terminology.


A. Both the 40A and the 100A are "line side" connections, they are just not taps, since they are feed from the busbar directly into the breakers (OCPD).
It is true, and more descriptive, that the two breakers are jointly the service disconnecting means.
If it were not for the up/down problem, the two breaker spaces currently empty could be used for PV connection and the would be line side connections also, connecting to the service wiring coming into the panel from the meter section.
If that configuration were allowable (e.g. if the panel had been turned 90 degrees), then the limit on the size of the PV disconnect breaker would be the 100A service rating. The 120% rule does not come into play here because there is no supply breaker feeding the bus! (Although I suppose some would argue that, as far as the bus is concerned, the PV breaker could be 120% of the 100A or 125A bus rating. But the limiting factor is still that the PV disconnect can not be larger than the service size.)

B. Yes, if there were a place to connect the wires without exceeding the number of wires allowed on existing terminals, it would be possible to add wires (not protected by OCPD and therefore tap wires this time) running to a new box next to the existing box, with the PV disconnect breaker located there. But the combo meter/main panels like the one shown often have a solid bus section running from the meter section (accessible only to POCO) to the main section. This bus would be under the shield at the lef tof the breaker bus and would not have anywhere to attach tap wires.

[foo1bar]

You are correct in your analysis, but marginal on your use of the terminology.

Ok - so please educate me (seriously - I'm not being sarcastic.)

Is it that I refer to the two breakers as "shutoff for the property" rather than "service disconnect"

If I'm misusing terminology, I would like to know so that I don't do that in the future.

This bus would be under the shield at the left of the breaker bus and would not have anywhere to attach tap wires.

There are the breaker attachment points though - I don't know if you can have a line-side tap that uses those or not. I've seen pictures of psuedo-breaker things that have no switch/bar on them and no over-current-protection which plug into a breaker busbar. The one I saw was being used to feed the breaker bus in the subpanel.
With no switch, the off=down/on=up rule wouldn't apply. But there's probably some other problem with that idea that I don't know of.

[solarfrank]

If you had the electrical main panel installed 30-40 years ago probably it's time for an upgrade. Many manufacturer from that time are out of business and many breakers are damaged by heat overtime. When you have a short breaker has to trip, but on many cases doesn't and melting the wire and it's a start for fire.
Regarding the price assuming 1500$ will be enough it's wrong, if you need also stucco repair professionally you will need another 700-1,000$. Average price for main panel upgrade in Southern California for 200A it is around 2,000 $. Extra costs can be in case of stucco repair, digging, relocation, distance from cold water pipe, upgrade pvc pipe to vault.

[inetdog]

Ok - so please educate me (seriously - I'm not being sarcastic.)

Is it that I refer to the two breakers as "shutoff for the property" rather than "service disconnect"

If I'm misusing terminology, I would like to know so that I don't do that in the future.


There are the breaker attachment points though - I don't know if you can have a line-side tap that uses those or not. I've seen pictures of psuedo-breaker things that have no switch/bar on them and no over-current-protection which plug into a breaker busbar. The one I saw was being used to feed the breaker bus in the subpanel.
With no switch, the off=down/on=up rule wouldn't apply. But there's probably some other problem with that idea that I don't know of.

OK, glad to.

1. The two breakers are collectively the service disconnect, so anything upstream of them will in fact be line side. That includes anything in the four empty slots at the top.
If, for example, there were another slot in the horizontal row that could accept a PV breaker, that would be a line-side connection. I was mostly concerned about your implication that the 40A breaker (if used as a PV disconnect instead of a subpanel feeder) would not be a line side connection. It might or might not be considered a "tap", but it would surely be line-side.
2. AFAIK there are no available components that would attach to the bus bar in the empty slots and could be used to feed a PV disconnect.
You can get things that look like breakers but have no current rating and are actually switches, but those could not be used either because they would be disconnects and would have to follow "up is on" also. You could drill and tap the copper bus bar in the empty section and attach terminal lugs to it, but that would be an unauthorized modification of the listed equipment. And would only give you access to one of the two ungrounded lines, since all of the opposite bus bar (except for the small stab connections) is under the installed breakers on the bottom side.

I tend to get picky about the terminology (like service disconnect) because when you are referencing the NEC the wording is critical to proper understanding.

[foo1bar]

You can get things that look like breakers but have no current rating and are actually switches, but those could not be used either because they would be disconnects and would have to follow "up is on" also.

There are ones that are same dimensions and connections as breaker - but no switch on them and no OCPD. I found picture of one that's similar to what I saw before - a "sub feed lug kit" - ex. Square D part is "QO60SL" (there's a few ebay auctions for QO60SL with pictures.)

Note for awhite if you're looking at this - I am NOT advocating using this for you. I have no idea if it'd pass an inspection - it seems like it'd theoretically work same as a line-side tap. But that's theory, and meeting code is a separate thing from theory.