How can I replace breakers in a Murray panel with future upgrade compatability?

Question

I have a Murray LC116DS circuit breaker panel. I want to replace the standard breakers (some alien) with AFCI's and GFCI's. I also want to be able to move these expensive breakers to a new subpanel in time, when I am ready for the generator transfer switch.

Here is my panel:

From the panel paper it can use:

class NI Murray MP & EP, ITE EQ-P, or Westinghouse Quicklag P.

From this topic: Murray Universal breaker it appears that Siemens makes Murray replacement breakers. From Siemens' website I got the Murray-to-Siemens cross-reference spreadsheet (Excel file) and I see that Siemens Q series replaces Murray MP series. So a Siemens Q115DF 1-space 15-Amp Dual Function AFCI/GFCI might replace a Murray MP MP115 1-space 15-Amp regular breaker, etc.

I also eventually want to put in a subpanel next to the Murray, with an appropriate generator transfer switch, and I'd like to move many of these expensive breakers to the new panel at that time. Here is the space I hope to use:

The black pipe may limit my panel height. Perhaps the Siemens SN or PN series, 100-Amp 30-space 30-circuit panel, about 28" tall, might be OK. The panels for sale are all plug-on-neutral now, but Siemens literature says their pigtail breakers will fit in their plug-on-neutral panels.

Does this plan make sense? Or do I have to do or use something different?

I understand that adding the subpanel may require a permit and inspection. But will the first phase, replacing all the breakers, require permit and inspection?

I am in New Jersey USA. The only major electricity user in the house is the central air unit. Stove, water heater, dryer, furnace are all natural gas.

Edit: adding another picture showing the panel wall, pipe and start of stairs, with dimensions. The drain pipe is 36-38" above the floor. The duct is 64 3/4" above the floor and 30 1/2" from the wall. The rafters are 69 1/2" above the floor. The open space from the stairs to the left wall is 64". The panel is 10 1/2" off the left wall. The front edge of the pipe is 4" from the wall the panel is mounted on.

Answer 1

Needing an inspection for a breaker swap is unlikely, but your best source is to call the local inspector and ask.

Your breaker progression seems like an acceptable process, but a bit complicated. I do see a concern about the piping, possible overhead ductwork, and probable wire protection.

Everybody is usually pretty quick to identify that NEC 110.26(A)(2) requires 30" wide working space in front of panelboards, but if you keep reading you get to:

110.26(E) Dedicated Equipment Space. All switchboards, switchgear, panelboards, and motor control centers shall be located in dedicated spaces and protected from damage. Exception: Control equipment that by its very nature or because of other rules of the Code must be adjacent to or within sight of its operating machinery shall be permitted in those locations.

(1) Indoor. Indoor installations shall comply with 110.26(E) (1)(a) through (E)(1)(d).

(a) Dedicated Electrical Space. The space equal to the width and depth of the equipment and extending from the floor to a height of 1.8 m (6 ft) above the equipment or to the structural ceiling, whichever is lower, shall be dedicated to the electrical installation. No piping, ducts, leak protection apparatus, or other equipment foreign to the electrical installation shall be located in this zone.

So in your case it looks like you will need to fur the panel away from the wall to get in front of the plumbing. If that is ductwork overhead you may need to shift to the right, you could possibly interpret the duct as above the ceiling even though there's no ceiling. Then your wiring becomes kind of vulnerable to damage and may require protection up to ceiling height (like a removable panel). That does also appear to cause stairway access issues, I would ask your inspector if he would give exception for the ductwork above the panel at existing location.

So then this brings me back to your progression. If your purpose for mounting a separate panel for generator loads was related to vertical space available limiting the height of panels then that no longer becomes an issue if you fur the panel away from the wall. I would inclined to think it would be less work and lower cost to mount a single larger panel with an interlock for the generator. You would also benefit being able to buy PON breakers and avoid the pigtail entanglements.

Answer 2

QP is indeed the correct breaker type for your panel (although a couple others are acceptable)

The other answer is correct that Murray MP breakers are obsolete, with Siemens QP (Qxxx part numbers) as the authorized replacement; however, there is more direct evidence that your panel is compatible with the Siemens QP line, as type QP breakers are the direct descendants of the ITE EQ-P breakers referred to on your label. Your panel also accepts Eaton HQP (aka "Westinghouse Quicklag P") breakers as part of its original listing, in addition to being able to take UL classified Eaton CL breakers, but I'd avoid the former as you won't be able to get a new panel that accepts Eaton HQPs.

That dedicated electrical space is going to be a pain

Your next problem is getting enough space out from the wall to comply with the NEC 110.26(E)(1)(a) spacing, as you'll likely need to either surface mount the panel over the furring strips (using cross unistruts or a plywood/OSB backerboard) or use deep (as in 2x8) furring to get the job done to Code. You'll also need at least 2 bays of furring in order to keep all the hardware at a reasonable height, especially given how tall modern panels can get.

The lack of the full 78" clearance, though, is not a pain point here. Since we aren't dealing with any equipment rated for upwards of 200A here, and this is an existing house, NEC 110.26(A)(3) Exception 1 applies to you:

Exception No. 1: In existing dwelling units, service equipment or panelboards that do not exceed 200 amperes shall be permitted in spaces where the height of the working space is less than 2.0 m (6½ ft).

As to panel selection...

I'd start the project by switching the breakers out for correct/upgraded (AFCI, as needed) ones; fortunately, not only do you have a slot spare, Siemens now makes a double-stuff AFCI (Q1515AFC). However, since your panel only permits double-stuff breakers in the bottom four slots, you'll have to switch breakers around if you want to use it instead of simply moving the extra circuit to the last remaining breaker slot.

Once you take care of that, we can then move onto the replacement panel. As you indicate, a Siemens PN3030B100C is a reasonable choice for the new panel, although you certainly could get a PN4060L1200C and retrofit it with a 100A backfed main breaker and hold-down kit instead.

Once all the breakers are moved over to the new panel, we can then look at generator transfer. Since your generator has a bonded neutral, just like a main panel, we'll need to use a transfer switch that has a switched neutral to avoid the consternation that dueling neutral-to-ground bonds can cause, which limits our selection quite severely, and prevents us from using interlock kits as well.

In fact, since we're working in Siemens breakers here, we're limited to one option, even, and that's a Reliance Controls Panel/Link X series transfer panel. I'd use a XRK0303D for this application, as it should supply enough slots to run most of the circuits you want to run, but options that provide more space are available.

With that transfer subpanel installed, using a 1.25" and a 1" rigid conduit nipple to connect the two panels together, we can then proceed to install the generator inlet (a NEMA L14-30 type, connected with 10/3 cable) and wire the transfer panel up. Note that the Reliance transfer panels do not support PoN breakers, as far as I know.