Sell him a 2 ser on a 90amp breaker. It'll cost less than what you're trying to sell him so he might go for it. Honestly when someone wants you to do the job their way and not necessarily the correct or your way it'll end up being a not great job.
It's common to do this too because of needing a true 60 amp circuit but 6 romex is only good for 55 amps and the next size up rule doesn't fly then. 6 SEU is way cheaper than 4-3 Romex and I've never seen 4-2 Romex.
Yeah I caught the 55A continuous load limitation at 60* for #6 CU; this #4AL SE cablr is rated at 65A@75* but I'm not going to tell the customer that or he'll want to try it. If it was a 4-wire feeder I might, but it's not.
Where is the subpanel in relation to the house?
It's on an interior wall in the laundry room of the house near the back door. The main panel is in the garage. The feeder runs through a breezeway attic connecting the garage to the house at the back door. I guesstimate the feeder is 65-70 feet long. I think the attic is accessible and I can pull the new feeder through the breezeway. The garage interior is unfinished.
Why I was asking is, 3-wire feeders used to be allowed to subpanels in a remote building (with stipulations) and are grandfathered. They were never allowed in the same building as the main. So in your case, a 4-wire is needed to be compliant.
.Have you done an actual load calc yet for the panel. I doubt it's that high of a load. Cost for 2 ser with 80 or 90 amp breaker will be 30% less than going to 1. It's a sweet spot for costs. It's only good for an 85 amp load at the lugs so even if you're down to 82 for the derate you're ahead of the game still.#2 aluminum SER? Might be a bit small. We've been in a heat wave, hitting 100* plus here for 2 weeks, and the attic has to be a lot hotter.
Normally it is low-to mid 90's this time of year, not hitting 100* until late July or August. Last summer was brutal as well. The wire will be through the unfinished garage rafters then in the attic so I'm not sure where to draw the line on ambient temp under these circumstances.
#2 aluminum SER derates to 91A at 40*C/104*F ambient, dropping to 82A at 50*C/122*F ambient.
#1 aluminum SER derates to 100A at 45*C/113*F ambient or 94.3A at 50*C/122*F ambient.
1awg AL may be reasonably priced due to popularity/availability. I'll have to price it out when the supply houses open Monday.
I know what you mean about a "not great job", but in this case he isn't trying to tell me what's right... he's just dealing with accepting the cost. Wife Acceptance Factor comes into play here too
A 90A would be a big improvement and could very well be the ticket. 80A might even do him justice, but at this point I'd rather see him spend the money on bigger wire than to wade through all the load calculation and guessing what he might add on to his house next. One and done is my M.O.
You might he on to something here. The garage was originally considered to be "detached", about 10' behind the house offset to the side with only the breezeway connecting it to the house. This MAY be considered a separate building...? I grew up in this neighborhood in the 70's, and that's how all the houses were built around here.
No, I haven't, and I don't look forward to trying to, what with all the additions he has made that I would have to wade through to discover. See my preceding posts, noting that the pool, ACCU's, cooktop, wall-mounted oven, the electric clothes dryer are fed from the main panel but the rest of the house and the original garage lighting and power circuits are fed from the original panel, along with all the additions to the house.
Are you sure they didn't have a dead short in a cord melting from a curler I've seen that trip feeder and main breakers before a branch breaker especially an old branch breaker with a new main.
I don't know yet. I asked him tonight if any other problems since the trip night before last and he said "no".
I understand your concern about the conductor sizing and type but from the description of the symptoms and the lack of certain calculations being done before doing a service change concerns me that there might be something else that's the cause of their electrical issues than just old equipment.
I haven't been to the house yet, but I'll certainly look closely when I do. I would think they would've said something if the curling iron or hair dryer smoked, and would've tripped the main (or at least a branch breaker) if they used it again. It is possible that they were just skating by with the 60a breaker before I came along and rebuilt the service and installed the house panel feeder on a 50A C.B. But this house has a LOT MORE running on the house panel NOW than it ever did when it was built in 1974.
Ah, Zinsco panels LOL. Replaced a few of them in my day. They like to burn up the bus bars and the breakers. I thought they were aluminum. Maybe it was zinc galvanizing on steel lugs and neutral bars?
Old Zinsco panels were plated copper, but they also made breakers with "push & pray" terminals. Zinsco plug in 3Ø was a strange beast, 100A plated copper zigzag bus bars covered w/ color coded shrink wrap, the bus stabs were staked into those bars.
