I've had a real eye-opening discovery. While the installs I see that have this detail are nearly as old as I am, the local town tells me that, in their opinion, the NEC still allows the practice, so they have a local ammendment.
The 'discovery' is that it's quite possible to hane NO main disconnect on a home ... not outside at the service drop, and not at the panel inside ... so long as you have six MWBC's or less. Hey, I can do a house with twelve circuits ... especially if all the appliances are gas!
Imagine that ... all the way from the PoCo transformer to the panel set well inside the house, with no means of disconnection. Let a rocker run a wire into that Romex feed to the panel, and the sparks won't stop until the PoCo comes out. Or the screw is vaporized. Or both. Add a 'tamper resistant' meter ring and you've just added to the danger.
I have issues with that. Current NEC says the 'disconnect' has to have a minimum 100 amp rating - but that's only IF you have a disconnect. Nor does the NEC require it outside, at the service.
I've had a bit of a chance to 'ponder,' and it's not only the 'six throws' that made the installation I described give me the willies.
Rather, it's the running of the service feed, without disconnecting means, to the interior panel ... where there also is no main. What really buggs me is that unprotected wire from the meter to the panel.
IMO, you need at least a disconnecting means AT the service. "Six throws" is acceptble THERE. I'd prefer breakers, but switches will do.
IMO, that mega-amp feed to the pane within needs better protection than the jacket of Romex can provide. In the house I am working on, someone pounded many 16d nails into the wall to hange things; only by chance did they not put such a nail into the stud bays with the service cable in it.
Indeed, a check of the records shows two fire department calls over the years, both for 'electrical shorts.' One resulted in a pretty substantial attic fire.
If you drive a nail into the SE cable, what difference does it make how it is protected on the load side of the fault?
There has always been discussion about the nebulous language of 230.70. You still have a few months to write a proposal and see how CMP 4 feels about it.
I still do not see it likely that anyone would try to wire a house without a main breaker. There is certainly no saving to be had if you did. The idea of having several MWBCs to save money falls apart when you go to buy the 2 pole AFCIs.
I could see some small commercial service in a warehouse doing something like this but they might only have a couple general lighting circuits and an HVAC fan.
We recently investigated a full blown hospital with a 4000 amp 480 service with six 800 amp disconnects and no main. The plan was to put in a 1200 amp PV disconnect on the common 4000 amp bus, the local AHJ approved this per 230.2 and 230.71.
The project was scrapped for financial reasons, but may be restarted if they can incorporate the work into a future expansion project.
I have never seen the six handle rule applied to such a large service.
Well duh, but a hospital is no place to be cutting corners.
I did nothing but hospitals from the mid 80's to mid 90's and that place is a nightmare compared to what I was doing before. All sorts of violations would have needed to be addressed before we could even put the new disconnect in the main electric room, doors opening in, lack of support, etc.
The as-builts were even signed off by OSHPD and this place was built in the mid 80's no less.
Greg, perhaps I was not clear on this installation ...
I was not referring to the SE on the outside of the house, before the meter. It's what came after the meter that concerns me.
From the meter enclosure, direct into the wall, up the inside of the wall, through the attic, and down a stud bay was a completely unprotected Romex feeder / service to the panel. The panel had no main breaker. So, you had a run from the meter to the bussbars without overcurrent protection. That's about 25 ft. of cable either inside the walls or over the ceiling without and cover but fiberglass insulation and cotton jacket.
In Chicago I saw a few places where you had an unprotected run - BUT the panel was directly behind the meter head, and the walls were solid brick.
In Reno I saw such a feed to a panel, BUT there was a main breaker at the meter - and the feed to the panel was in EMT.
With this arrangement, I have a panel where I have no choice but to work 'hot.' But, hey, there are the required 'disconects' to the branch circuits!