Up grade/ retrofit lager combination service panel, delete flanges?

[Homeownerinburb]

Hey guys,

I'll be doing a fair bit of work on a home that is changing hands in a few weeks.

Among the items to do, the main service panel will be getting replaced. Currently there is a separate meter a foot or so above a very dated and scary 100 amp (in fact, there is not even a main breaker) Zinsco nightmare. Both are flush fit in a stucco wall, and this wall is adjacent to the driveway, so the new needs to be flush fit as well.

We are going to put in a 200 amp panel (although really 100 amps is enough) and for these purposes I like a Murray JA2040B1200F. This is a nice combination flush fit that has the meter in a section above space for 20 breakers, I like this as opposed to those split vertically as it really is snug working the wires in those combination panels.

The power company has speced out a 2" mast rising 54" above the roof line, as the whip passes over the driveway, and the power company wants as much of 16' as they can get without forcing me to use a guy wire to support the mast.

The Zinsco nightmare is less than 14" wide, but happily the stud pocket is full width, there is a hinged cover that is not part of the actual panel but is just a weather cover.

Now, here's the question: when I pull out the weather cover, hopefully not destroying any more of the stucco than is essential, I would just as soon take off the flanges that Murray gives me to mount the panel to the stud faces, as if this was new work. This is retrofit, and I'd rather just run for 1 1/2" lag screws sideways thru the side of the panel into the studs, in order to do the least damage to the stucco as practical.

Anybody know if that is incorrect? "The equipment shall be used the way the manufacturer intended" or something like that?

Lord knows I'll be making enough of a mess as it is. I need to cut all the stucco above the new panel away, to the top plate. I need to install two 2" x 1/4" straps with beefy U bolts to restrain the riser, and I need to cut a BIG hole in the top plate for the riser. I prefer to place the riser all the way forward such that I just cut a deep slot in the top plate, then I can scab over it with a nice thick steel mending plate, to help reinforce the top plate. This is earthquake country and one should not just go cutting up structure willy nilly.

For the benefit of the stucco meister, I'll break out all the stucco on the wire that needs to go, and cut away the wire up the center, and cut the tar paper neatly about 2" from the studs. The stucco meister should be able to pull that back together and make a successful patch, I would think.

Any thoughts short of actual derision much appreciated.

[Glennsparky]

Your inspector has the final say. I've always found inspectors to be helpful and patient. Ask before you do the work. I like the idea of screws, but one inch is plenty long enough, or predrill. I'm worried you'll split the wood.

Fun facts: conduit riser. Intermediate (IMC) is stronger than rigid (RMC). Either can be upgraded to stainless steel.

The top plate has me really worried. But structural is out of my league. I go by these rules, but it's rote knowledge.


"Drilling and notching of standard wood members is subject to the following:
Notches in joists, rafters, and beams may not exceed one-sixth of the depth of the member, may not be longer than one-third of the depth of the member and may not be located in the middle third of the span.
Notches at the ends of a*joist, rafter, or beam may not exceed one-fourth the depth of the member.
The diameter of holes bored or cut into joists, rafters, and beams may not exceed one-third the actual depth of the member. Holes may not be closer than 2 inches to the top or bottom of the member or any other*hole*located in the member. Where the member is also notched, the*hole*may be no closer than 2 inches to the notch."

Sometimes we get things signed off by an architect or engineer.

[Homeownerinburb]

"Notches in joists, rafters, and beams"

What is interesting is that the top plate is neither a joist, rafter or beam. It really carries very little weight beyond the end of one joist and rafter.

It is a done thing to pass a riser thru the top plate. A 2" rigid conduit is what? 2 1/2" in outer diameter? Assuming the wall is made of 2x4s, I cut such a notch in the top plate and have nothing more than 1" of wood left behind. I generally want to reinforce such a notch with a nice thick plate lag bolted to the top plate, spanning a good ten inches. Or twelve.

If this was an installation on open framing, I'd have a 2x8 notched around the riser fitting over the top of the top plate spanning between the joists, where blocking would normally be, extending over the ceiling. Some 16 penny nails should tie it together well.

[Glennsparky]

thank you to stickboy1375 for this link to "Notching and Boring - IBC Section 2308 & IRC R502.8 - R802.7.2." (it was news to me.)

http://www22.pair.com/routt/building...s/notching.pdf

this is the top plate section.

R602.6.1 Drilling and notching of top plate. When piping or ductwork is placed in or partly in an exterior wall or interi-
or load-bearingwall, necessitating cutting, drilling or notching of the top plate by more than 50 percent of its width, a galvanized metal tie of not less than 0.054 inches thick (1.37mm) (16ga) and 11/2 inches (38mm) wide shall be fastened to each plate across and to each side of the opening with not less than eight 16d nails at each side or equivalent. See Figure R602.6.1. Exception: When the entire side of the wall with the notch or cut is covered by wood structural panel sheathing.

to me, it sounds almost like your original plan. kudos to you.

[Homeownerinburb]

[QUOTE=Glennsparky;373495

to me, it sounds almost like your original plan. kudos to you.[/QUOTE]

Thank you! I do feel I have a pretty good seat of the pants engineering instinct. I drive a car that I pretty much built. I got lots of advice, but in the end, one needs to take responsibility for one's own work.

I will certainly be adjusting my approach to reflect what you showed me about the 16ga mending plates and the 16pd nails. I'm only going to do it from the outside unless the inspector insists otherwise......