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Just bought a new house, first time homeowner. Familiar with electric (studied electrical/computer engineering) which helps but doesn't directly translate to AC stuff. Currently making plans for redoing things and wanted to get another set of eyes on it. I want to be clear that I am not an electrician, but I DO want to do the work myself (learning is half the fun) and I want to go above and beyond code to make inspection and future work easy.

The home was built in '51, and the electric that was in place when we were negotiating the purchase was fused. Part of the purchase agreement had the sellers getting electric re-done with breakers. The breaker box itself looks fine - 100A service, and 14 circuits. That said, the work that was done seems lazy to me: a lot of the original wiring was left in place - and it was only 2-prong stuff, no ground, so I'm not sure if that's even kosher/grandfathered given the panel upgrade - and the labeling is really vauge: 3 separate 15A breakers in a row labeled "lights" while outlets, water heater, and furnace aren't listed anywhere.

Fortunately the basement and attic are open, which should make running new lines pretty straightforward. My tentative plan is something like this:

  1. Flip the main 100A service breaker off to cut power to the house.
  2. Pull all 2-prong-only wires
  3. Reposition good lines (line out to A/C seems good, but I'll try to group it in the MSP in a more logical place next to utilities - line to the range seems good but we're remodeling the kitchen and moving the range to the other side, so I need to relocate the outlet)
  4. Rip out all non-3-prong outlets, including one placed confusingly between the shower and toilet near the ground
  5. Install old work boxes for new switches
  6. Place 3-prong outlets into original work boxes if they're in good shape, otherwise place old work boxes
  7. Add ceiling light fixtures/fans to each room (there are 2 total ceiling light fixtures anywhere in the building)
  8. Add dedicated circuits for each garbage disposal, refrigerator, and to-be-installed dishwasher
  9. Run all necessary new wiring (mostly outlets and lights)
  10. Flip off all breakers
  11. Flip on main 100A breaker
  12. Flip on breakers 1 at a time checking for problems

I've also been planning out what circuits will go to what regions of the house, and derated rather generously, but I'm not sure what qualifies as a "circuit" - for example, I currently have 2 breaker slots occupied for a 30A breaker going to the range: is this 1 circuit or 2? In the text below, I'm calling it 2 - but for permitting if that's only 1 that's great. Unless specifically noted, these are 15A 120V breakers.

  • Living Room: 1 circuit: 5 ceiling light fixtures, half a dozen outlets, entry way and porch lights.

  • Garage: 3 circuits: (2) for 240V socket for future EV charger, (1) 20A for lights, garage door opener, and outlets (particularly for
    tools which might need higher current)

  • Dining Room/Kitchen: 6 circuits: (1) for lights + outlets (GFCI in kitchen), (1) for Fridge, (2) at 240V for range, (1) for dishwasher,
    (1) for garbage disposal.

  • Bathroom/Hall: 1 circuit: GFCI outlets in bathroom, lights in bathroom/hall, hall outlets, bathroom fan

  • Primary Bedroom: 1 circuit, 20A as a future-proof because I have a lot of electronics: lights/ceiling fan, closet lights, outlets

  • Secondary Bedroom: 1 circuit: lights, ceiling fan, outlets

  • Downstairs landing area: 5 circuits: (1) for washer, lights, outlets, and downstairs backdoor light - think I might need to do a dedicated circuit for washer, unsure (2) at 240V for dryer, (2) at 240V for A/C which is physically close to this area in the basement

  • Utility Room: 1 circuit: light, outlets, furnace (natural gas), water heater (natural gas), possibly future on-demand water heater (also natural gas).

  • Guest Room/Bathroom: 1 circuit: lights/outlets/ceiling fan/closet lights, GFCI outlets in bathroom, bathroom lights, bathroom fan

  • Theatre Room: 1 circuit: lights, outlets (TV/sound system will be on outlets here)

  • Primary Downstairs Bedroom: 1 circuit, 20A for future-proofing: lights/ceiling fan, outlets, closet lights, bathroom outlets (GFCI),
    bathroom lights, bathroom fan

I count a total of 22 - or 23 if the washer needs a dedicated circuit - circuits, assuming that the double-wide breakers count as 2 circuits.

Is anything obviously amiss with my plans? Any tips that will help make this a smoother process - particularly inspection? Any problem with nearly filling the 24 breaker slots on my MSP? Will I need to upgrade service to >100A?

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    #4: a receptacle down near a toilet was probably there for a bidet seat. Not my cup of tea, but some people like them. Apr 18, 2023 at 3:16
  • @AloysiusDefenestrate That makes a lot of sense! Still a bit odd to me that it's the only outlet in the entire bathroom, but at least it has a purpose.
    – user112697
    Apr 18, 2023 at 4:07
  • Only receptacle? Should be one to serve counter and there are specific dimensions. Depending on wiring, can add one usually at switch or near lights. Apr 18, 2023 at 13:12
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    As a DIYer, I wouldn't recommend you pull out too much at one time. Just having live circuits to charge tools or run lights so you can keep working/living can take your job from very painful to workable. I would only pull out what I could confidently replace in a short period of time (1-2 days). You can always pull more out if you get through it faster than you thought. I know it can be easier to do all the demo first, but with electrical or plumbing it can also make things more difficult. Apr 18, 2023 at 19:30
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    As a fellow DIYer with a similar background -- ran some lines myself and paid electrician to replace panel -- I would really recommend you experience firsthand what it's like to run just one circuit before committing to a ton work you've never done before. And secondly, give a long hard thought on whether you really need a ground (e.g. in the bedroom -- of course it's required for appliances) or whether a GFCI receptacle will suffice. My living room tv and related devices ended up on a GFCI circuit ...
    – BurnsBA
    Apr 19, 2023 at 13:41

2 Answers 2

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I DO want to do the work myself (learning is half the fun) and I want to go above and beyond code to make inspection and future work easy.

Please - get a book, better several books on home electrical and read them through and through. Do not attempt to plink the knowledge with Google... Google only answers questions, it does not tell you which questions to ask.

Past electronics skills do not prepare you for mains electrical, which is all about mechanical execution of work and has no EE at all. It is also wired as an isolated system with each circuit having a neutral that serves only it. Very important, that.

Part of the purchase agreement had the sellers getting electric re-done with breakers. The breaker box itself looks fine - 100A service, and 14 circuits. That said, the work that was done seems lazy to me

Asking the seller to do it means you got the cheapest possible execution. One generally prefers a 40-space panel for a whole house - spaces are cheap (up to 40, at least).

a lot of the original wiring was left in place - and it was only 2-prong stuff, no ground, so I'm not sure if that's even kosher/grandfathered given the panel upgrade

Doing a panel upgrade does not break the grandfathering on the other old work. (old Zinsco and Federal Pacific panels are actively dangerous, as are classic Rule of Six panels, and both should be replaced with all due haste, so they make panel replacements as low-friction as possible).

I'm not sure what qualifies as a "circuit" - for example, I currently have 2 breaker slots occupied for a 30A breaker going to the range: is this 1 circuit or 2?

Here is a great video talking about America's split-phase power system. Note the weird breakers and the way the panel is interleaved. The important thing is your 240V loads take 2 breaker spaces.

Garage: 3 circuits: (2) for 240V socket for future EV charger

Do not install two 240V circuits for EV charging. Multiple-EV charging should be done using Power Sharing, where the two EVSEs (wall charge units) automatically coordinate to use a single current allocation best. This is live, in-production tech right now, sold on a variety of units e.g. Clipper Creek... and Tesla gen 2 and gen 3 units, including the one with a J1772 port, so it's available in mixed homes.

EVs only need 2 wire + ground, no need for neutral. However, the free EV "travel unit" has a NEMA 14-50 RV socket specifically so you can charge at RV parks while traveling, as a last ditch option... misunderstanding this, many lemmings will tell you that you need a 14-50 socket to charge at home. This advice is several kinds of wrong. But if you do fit a 14-30 or 14-50, it needs a neutral because it's a socket.

Garages also require one 20A dedicated receptacle circuit, for ironically EV charging. I will argue this is dumb if installing a dedicated 240V EV circuit.

Dining Room/Kitchen: 6 circuits: (1) for lights + outlets (GFCI in kitchen), (1) for Fridge, (2) at 240V for range, (1) for dishwasher, (1) for garbage disposal.

When you do this kind of rewire, you must bring it up to current codes. Kitchens require at least two 20A circuits dedicated to general-purpose (e.g. countertop) receptacles. As a practical thing, most kitchen plug-in heat appliances are 1500W (12.5A) so only 1 per circuit at a time. The dedicated fridge circuit is not required (it's a small load) but it is wise, so a trip from other appliances doesn't knock out the fridge.

Primary Bedroom: 1 circuit, 20A as a future-proof because I have a lot of electronics: lights/ceiling fan, closet lights, outlets

Don't get tidally locked to the concept of "1 circuit per room". This is somewhat dumb, and wastes wire. Outside of kitchen and bathroom, you are welcome to mix-and-match other rooms as you see fit. One way I think is economical is "1 circuit per wall" (within reason). That keeps run lengths short (no circumnavigating rooms, lines passing each other in shared walls). It also gives each room access to 2-4 circuits, so that when you have a home office or craft room that needs a lot of power, you can find it.

Laundry and garage each require 1 dedicated 20A circuit. However (unlike kitchen and bathroom) they are welcome to have any other circuits also serve receptacles there.

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  • This is fantastic advice all around and I'm in the process of reading it repeatedly. Also currently reading about GFCI requirements in bathrooms/kitchens, so there's definitely some info I'm missing - one of many reasons I posted here. Per your first recommendation: any suggestions on books I should be reading now? As far as the garage: Planning on 2 breaker slots feeding a single 240V outlet in the garage, not 2 separate outlets.
    – user112697
    Apr 18, 2023 at 1:15
  • @user112697 Learn about what version (likely locally modified) of the National Electrical Code applies to your house. This will especially impact what type of panel/service/shutoff is allowed, and what types of GFCI and AFCI are required for the circuits in different types of rooms.
    – Armand
    Apr 18, 2023 at 4:25
  • @user112697 Re: books for basics: I would get at least 2 specific books - one just on wiring (types, conduits/raceways, rules, installation), and one a room-by-room summary of code requirements for each room (mostly type, count and spacing of outlets). Finally, learn about how to properly make connections - screw terminals, wire nuts and required torque values.
    – Armand
    Apr 18, 2023 at 5:31
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In addition to all of Harper's wonderful (and correct) advice, a few more things based on my own 1950s house:

  • Panel and Service Size

As Harper noted, the panel should have been a larger (e.g., 40 or 42 space, depending on brand) and 200A (not 100A) panel. In most areas, 200A has been the standard for a while. When I replaced (all real work done my a licensed electrician with permits, but I had fun helping) my 2 old fuse panels + 1 small breaker panel with a 42 space breaker panel, it was a given that this would officially be a "heavy up" to 200A service. I didn't add any new loads (did add a generator inlet and split some previously combined circuits) so I didn't actually need more power, but that was the way to get things done properly. I wouldn't be surprised if the 100A 24 space panel was just the absolute cheapest way to do your panel replacement, including saving a few $ by not having to replace the feed wires from the meter to the panel. As long as you stick with gas water heating, you are probably fine for now. But do consider that if you add EV charging then you may run into total load issues with 100A service.

  • AFCI and GFCI

In most places, AFCI and GFCI are not required except on new circuits. In my case that meant the only circuit that needed GFCI added was a receptacle right next to the panel which had to be replaced for practical reasons, so the electrician told me it had to be tamper resistant (because everything is supposed to be TR) and GFCI (because basement). But while my electrician made my kitchen all GFCI 22 years ago and took care of the bathrooms a few years later and other circuits as he added them, I have plenty of other receptacles (basement, laundry room, outside) that are properly grandfathered. Replacing the panel doesn't change that, but replacing the wires and receptacles would.

In particular this is an issue for 240V circuits in NEC 2020 areas (unless local modifications exempt them). And that in turn applies particularly with EV charging. Hardwired EVSE (a.k.a., "chargers") includes GFCI. But plug-in EVSE requires GFCI (where required for 240V circuits) because you could use the same receptacles for other stuff. Which means GFCI/double-breakers which are not cheap. (My electrician can tell you his horror stories...) That is an additional reason to not wire up receptacles for EV charging. Wait and install proper EVSE. If you want to run cables or conduit in advance, do that. But don't install receptacles.

  • Grounds

My house, like yours and most 1950s homes, has (had) mostly ungrounded receptacles. However, as I have set about replacing them with 3-prong receptacles I have found that all of them (so far, not done...) actually had a good ground wire already in or attached to the box! Which means that I didn't have to (a) run new cables or (b) run a separate ground wire (which is allowed now, it has not always been an option) or (c) install GFCI in lieu of ground (GFCI functions differently from a traditional ground wire, but it effectively compensates for the lack of ground).

So definitely don't rush to replace all the existing wiring, especially not to get grounds (as you may already have them anyway). I would only replace wiring if there is damage due to rodents, water, etc.

  • Circuit Labeling

All circuits should be identified. There is no good excuse for not labeling all 240V appliances (clothes dryer, oven, cooktop, HVAC, etc.) and all hardwired 120V appliances (dishwasher, disposal, etc.). But in reality most older houses (and a lot of new ones too) have a few catch-all circuits for lights and receptacles. They are often referred to as "lighting circuits", and they often snake through several rooms so they can't really be identified as "living room" or "master bedroom", etc.

  • Dedicated Circuits

There are a bunch of specific dedicated circuits. Most (maybe all) of these were not required in 1951. For a bunch of reasons they make sense, not just "to meet code", so adding them as you have time/money/opportunity to do so does make sense. They include:

  • At least 2 kitchen countertop circuits (i.e., to serve small appliances on the kitchen counters). These can each have several receptacles but are basically limited to kitchen receptacles and not other rooms and not other appliances (wall clock, gas cooktop are the main exceptions).
  • Bathroom receptacles. One circuit can serve multiple bathroom receptacles. One circuit can serve receptacles + lights for one bathroom. But one circuit can't serve receptacles in bathroom + other rooms.
  • Laundry - which really means washing machine, as the dryer is a different (240V) circuit anyway.
  • Any hardwired device using at least 50% of the circuit capacity. Typically that is things like a dishwasher. But it can also include a circuit for a bathroom heater - e.g., I have a circuit in each full bathroom for heat/light/fan (in addition to circuits for receptacles and the original lights).

You can have additional dedicated circuits. Refrigerator can make sense, though there the concern is usually not that it needs a dedicated circuit due to power requirements - I have a basement refrigerator/freezer, freezer and several other receptacles in several rooms all on one of those "lighting" circuits and never have an overload. The concern is about putting a refrigerator on GFCI and risking a nuisance trip leading to food spoilage. If your kitchen is arranged such that a refrigerator receptacle will inevitably be near either a sink (need GFCI within 6' of any sink) or a counter (therefore being part of the kitchen countertop circuits which are normally all GFCI protected) then the usual solution is a dedicated circuit with a single receptacle (rather than the usual duplex) for the refrigerator. But if your refrigerator receptacle can be positioned in a way that it is not near a sink and not perceived as a countertop receptacle (out of easy reach) then that should not be an issue and GFCI should, arguably, not be required anyway.

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    Re: bathroom circuits: since the receptacles in the bathroom will all be GFCI, make sure the lighting in the bathroom is not GFCI - it should be either upstream of the GFCI or on a different circuit. You don't want to be trying to reset a GFCI in a dark bathroom.
    – Armand
    Apr 18, 2023 at 4:21
  • @user112697 Re: panel and service size: it will likely be easier and cheaper to upgrade your service to 200A or 400A now and install a much bigger panel (better quality might be an issue too).
    – Armand
    Apr 18, 2023 at 4:28
  • Also with bathroom receptacles, running multiple hair driers or other high draw devices at once can trip a breaker so a dedicated circuit bathroom isn't a bad idea. Apr 18, 2023 at 23:36

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