Does the sub-panel seem over loaded? If so, I could keep the water-heater in the main panel and free up space in the panel another way.
Seems reasonable to me. Most of the equipment won't draw anywhere near the overcurrent rating, at least not during normal operation. Motor loads will draw a higher current on start, but you shouldn't have a problem.
I know I need four-strand wire to run to the sub-panel (2 hot, neutral, ground) but copper or aluminum and what gauge?
You can use either copper or aluminum, though I recommend copper for DIYers. Copper is quite a bit more expensive, but it's easier to work with (in my opinion). If you feel confident working with aluminum conductors, you can save some money using it.
I've covered the topic of feeder sizing here, so I won't go into detail. If you're using copper, you'll want to use 3 AWG conductors. If you choose to use aluminum, you'll need 1 AWG conductors.
If you want to run a single cable, instead of individual conductors in conduit. You can buy what's called 3-3-3-5 SER cable (1-1-1-3 for aluminum), which will contain three 3 AWG conductors (hot,hot,neutral) and a 5 AWG grounding conductor.
When I run the wire along the floor joist, does it need to be secured to the joist or can it just hang there and rest on the drop ceiling? Seems like it should be secured to the joist with wire hanger or something.
You'll have to attach the cable to the joists, using 1 - 1 1/4" staples or other approved means. Check the packaging, to make sure they are rated for the size cable you're using.
What are the things about this project that I don't know that I don't know. :) These are the scary things IMO...i.e. the questions I don't know enough to ask.
The cable you'll be working with is thick and heavy, and it's not going to be fun pulling it. You'll probably want a couple helpers, to help you wrangle it.
Make sure all your connections are tightened to the manufacturer's specified torque.
If you choose aluminum conductors, make doubly sure you tighten the connections. And don't forget the anti-oxidant.
Come back a day or two after the panel has been put into service, and tighten any connections that need it.
Don't forget to remove the bonding jumper between the grounded and grounding bus bars.
You'll need clamps big enough for the cable, to secure it to the panels.
should I put a 100 amp breaker in the sub-panel to act as the "main" for the sub-panel? Or is the 100 amp breaker in the main panel sufficient?
You can usually pick up a main breaker panel, for about the same price as a main lug only (MLO) panel. In my opinion, unless the secondary panel is next to; or within sight of, the main panel. You're better served to install a main breaker panel. It simply offers better protection during maintenance, or other work within the panel.
For example. If you turn off the feeder breaker in the main panel, and start working in the secondary panel. Somebody could easily come along, and flip on the feeder breaker. Since you can't keep an eye on the breaker, you can never be sure the panel will be dead. (unless of course you're using a lockout like you should).
If the secondary panel is in a separate building or structure, then you either need a main breaker, a main disconnect, or the ability to disconnect all ungrounded conductors within 6 or less hand moves.
Quote: "The bedroom outlets that I tested were pulling 36-49 amps."
Sounds fishy. Outlets do not pull any amps by themselves. Did this electrician plug in to the outlet with some kind of test load to draw this power? If not, the electrician is probably not honest or does not know their job. I was an electrician for about 10 years, granted that was 30 years ago but I have never heard of testing the "amps pulled by an outlet" since outlets do not "pull power" at all, only the load (your lamp, tv, or whatever) plugged into the outlet "pulls power."
Finding the breaker at the panel is easy:
This paragraph assumes you have only one breaker panel and is a good place to start if you don't happen to know.
Plug a radio into one of the outlets in question and turn the volume up so you can hear it from the breaker panel. A lamp works also but you have to run back and forth to check if the lamp is on.
Turn off all 15 and 20 amp breakers one at a time. You should hear the radio go silent when the proper breaker is turned off. If there is still power to the outlet(s) in question after all 15 and 20 amp breakers are off, then it would be logical that they are not wired properly and may well be wired to a higher amp breaker. Skip the next paragraph in that case.
If you found the breaker that controls the outlet(s) in question you can replace the breaker if you want to be sure there is no problem with the breaker.
If the outlets are not powered off after all the 15 and 20 amp breakers are off, then try the higher amp breakers one at a time until you find the guilty breaker. THEN, be sure you do not have a sub panel somewhere that is fed by that high amp breaker. If you do, then you need to start over with that breaker panel.
BTW, even if there is no "amps problem" you may still want to open all the outlets and check them if one had melted insulation. That is almost always caused by a poor connection or nicked wire. The outlet was likely not installed properly to start with.
Another reason the outlet may have failed, since the electrician claimed that it melted from the inside, is that a heater or other high draw appliance was plugged in loosely. That would cause the same problem as a bad connection to the outlet. In fact it would be a bad connection, just that it happens to be the plug, not in the wall wiring. If your outlets are worn out, that is, you feel little or no resistance when you plug something in, they are a fire waiting to happen when someone plugs a space heater in.
Best Answer
He condemned a QO panel... Without even opening it??
QO is Square D's top line industrial grade panel, and it's current stuff. The way panel pricing works, you can get the industrial grade for just a few dollars more. (Square D also sells a residential grade line called literally Homeline, it is acceptable also, but QO is excellent).
So he's just wrong. And chasing dollars obviously. More disturbing... he didn't open with obvious defects in the location of the panel - or to be more precise, remodeling done around the panel. The original electrical work was well-done, but then somebody decided to "finish" the space, and disregarded the electrical codes, probably because they were a carpenter.
One wonders if the work was permitted, since what AHJ would permit a clothes closet being placed in front of an electrical panel?
The closet needs to be demolished (or at least truncated) so there is a work zone in front of the panel. It must be 30" wide (the panel can be to the left or right side of that 30") and 36" deep so the electrician can stand at arm's length. It must have at least a 6' ceiling so a fella can stand. And you must keep it clear of stored junk.
This is a $500 carpenter job, not a $4500 electrician job. Unless the closet is sacred for some reason; did George Washington hang his coat there? Maybe he hung his coat in the left side of the closet.
Aluminum
I'm sure the electrician told you a lot more than that... But the aluminum thing is what stuck. There was a problem in the 1970s with shoddy use of aluminum wire with receptacles (wire terminations/clamps) that had not been properly approved for aluminum, and this resulted in a lot of arc problems which led to house fires. Easily fixed with arc-fault breakers, but there is still an ooga-booga fear, moral panic style, where any aluminum wire of any kind is consided "cootie". Certainly a shoddy electrician could scare you into doing unnecessary work by mentioning the A-word.
The aluminum excuse is balderdash. Actually service and feeders are aluminum for good reason, and aluminum performs just fine in these large wire sizes. So you want lugs to be aluminum, since aluminum lugs are the universal donor - they work with Aluminum and Copper both. Copper lugs don't play nice with aluminum wire (and actually, that was the problem all along).
Even today, aluminum is not used for small branch circuits (lights, sockets, dryer etc.) because of the cootie. The alloy has been improved, the now-noncopper terminations have been vastly improved, and it's legal... Just nobody does it.
Now on panels, here are brands I would consider solid and not even think about replacing:
Zinsco, Stab-Lok and Federal Pacific (in US) are dangerous and must be ripped out. Pushmatic is a fine panel, just obsolete.
If it were me...
The undiscussed problem here is that your panel is full/overfull. It looks like you have plenty of service, but are using "double stuff" breakers to get enough circuits.
Here on SE, we love large panels. Because many circuits today need AFCI or GFCI protection, and those breakers are not available in double-stuff. What's more, it's very frustrating to not be able to install something new, like an EV charger or hot tub, because of a full panel.
So. That's a 30-space panel, looks like the standard size that fits between 16" joists. I would get another one as a subpanel - also 30 space, also QO, but main-lug (no main breaker). Fit it in the next joist bay over so it fits in the same 30" wide electrician's work space. Move 2-4 circuits over to the new subpanel to make space, then fit a 100A breaker in the main to feed the subpanel.
You'll have 58 total spaces, which is a very happy number for a medium/large well-equipped house.
Now you can add anything you please without concern. And if a couple bus bars actually are arced up, just stop using them - leave the arced breakers in place connected to nothing and move the wires to new breakers.