Discussion in 'Electrical Forum discussion & Blog' started by pensfan84, Nov 2, 2009.

  1. pensfan84

    pensfan84 New Member

    Pittsburgh, PA
    I recently purchased my home that was built in 1930 and found that 80% of the house is on one single 20A knob and tub circuit.


    So while I'm working on my bathroom and have a portion of the first floor tore out, I'm going to rewire the house.

    I have 8 spaces open in my circuit breaker box currently to put in new circuit breakers. 3 of those will be taken by the new bathroom, (15A for the lights, 20A for the outlets, 20A for the whirlpool tub).

    Now, when I say nearly the rest of the house is on a single 20A circuit, I'm not joking.

    I have access to all ceiling lights and outlets through the basement and the attic.

    Included on this rewire will be the first floor - on the first floor there is a living room, dining room, hallway, and office.

    I have a lot of power draw in my office so I will be installing a 20A circuit in there. Due to my home theater equipment, I assume it would suffice to say that it would behoove me to install a 20A circuit for the living room, correct? Would a 15A circuit suffice the dining room light and outlets?

    With all of my thoughts above - here is my question:

    How should I rewire the spaces of the house I have listed? What type of breaker should I install (15A/20A) and what areas should it service? I know electrical code as per wire gauges for each circuit type, but I am not sure of what areas each circuit should service.

  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    New England
    While you have things open, you may want to put in a new panel. The kitchen by code needs at least 2-20A circuits for just the counter outlets, not counting lights/frig/DW or any other things. Plus, current code requires AFCI breakers for bedrooms. You may want to install wired (battery backup is good, too) smoke detectors. These need a 3-wire setup with the third wire as the remote trigger so if one goes off, they all do. Laser printers have gotten more efficient, but the heaters on one of them can draw some heafty current, and you may want more than one circuit to feed your computer stuff. Depends on how extensive your home theater stuff gets, one 20A circuit may or may not be enough. Got a few thousand W audio system, and a big screen, and it can get messy when the bombs start going off and the bass rocks the house! You may never get an easier opportunity to do it now. You may also want to consider running some RG6 and maybe some CAT5/6 around, too.
  3. Billy_Bob

    Billy_Bob In the Trades

    Don't forget about things like vacuum cleaners, rug cleaning machines, space heaters, and window air conditioners!

    And if remodeling your house... air compressors and power tools which can draw quite a bit of power.

    For things like this and problems I've had in the past with 15 amp breakers tripping, all of my 120v outlet circuits are 20 amp. End of problems!

    Also it makes it easier if all the wiring you are running is all the same 12 gauge.
  4. Ford2001

    Ford2001 New Member

    Manchester, Vermont
    re-wire my house?

    pensfan84, I can't speak for the rest of the guys who will come on line
    and reply to your thread.

    First I would, get rid of all knob and tub wiring. Insurance company do not
    like to insurance homes when they find out it in your home.

    Since you have an existing electrical panel, I would install a min. of
    150 amp. to 200 amp. service. And run sub-panel if necessary.

    You can bring all your new circuit to your new electrical panel, and
    run power from the existing panel to temporay power the new panel.

    When all is done, take the service cable out of the existing panel,
    and install it in your new electrial panel. Don't forget to ground the
    service neutral at your new electrical panel.

    If the existing service is old, and the existing service cable will not
    reach your new panel. You will may need a service meter socket, with
    with new service cable.

    I just finish one, I use two Home Depot panels, and wire then side by
    side. The customer love it. Plus he had lots of room for addition
  5. pensfan84

    pensfan84 New Member

    Pittsburgh, PA
    I'm having my service updated to 150A with a new box to support on Tuesday.

    I will be rewiring as much of the house as possible. In this process I will pull out whatever knob and tube I have access to, and the rest I will just disconnect from the panel.

    I know the code I need to follow for kitchen and bathroom wiring, as well as any device with a motor in it; however, I am unsure of the code for light fixtures and how many of them should be on a given 15A circuit. I have less than 6 fixtures per floor - am I able to install a single circuit per floor that will cover the light fixtures?
  6. hj

    hj Moderator & Master Plumber Staff Member

    Cave Creek, Arizona

    You DO NOT need ANY 15 amp circuits if you want to run them all as 20 amp that is perfectly acceptable as long as you size the wire properly.
  7. pensfan84

    pensfan84 New Member

    Pittsburgh, PA
    I know that I don't need any 15A circuits, my question was more along the lines of which rooms need to be on their own circuits for outlets, and should the light fixtures be on their own circuit separate from the outlets? Or is it easier just to wire each room's outlets and light fixtures on the same circuit?
  8. Billy_Bob

    Billy_Bob In the Trades

    With rooms other than those with required outlets per code, you can pretty much do what you want.

    Check with your local inspector as to what is required. Also ask about child protective outlets, AFCI, GFCI, garage/outside/basement, interconnected smoke detectors [when rewiring whole house], and required lighting/outlets for dining area if any.

    Many states modify the electrical code. Ask where you can get a copy of the amendments (if any).

    It is handy to have all the lights on a separate circuit. Then if a breaker trips, you still have lighting.

    Or be logical about it. Each room on its own breaker including the lighting for that room.

    The BIG question is YOU and what all you might possibly use electrically in each room. And what the wattage of everything is. Then convert that to amps. A good rule of thumb is to not exceed 80% amperage load of a circuits capacity "at the same time".

    The "at the same time" question is the trick. For example you might have a space heater and a window air conditioner at the same location. You would not have both on at the same time! (Or at least I wouldn't...) So one 20 amp outlet will work for both. [Both on at the same time would trip the breaker.]

    Or in your living room you might have a "neighborhood blasting" stereo/TV*, a window air conditioner, and the outlets for the room. In that case might want to put each on their own circuit and breaker.

    Or you might want to install a window air conditioner somewhere in the future. What is the wattage?

    Basically add up the wattage of EVERYTHING you might possibly have on at the same time, then convert to amps.

    Watts to amps calculator, use the single phase...

    *As to the neighborhood blasting stereo, I seem to recall someone on the internet a while back wanting to install a breaker subpanel JUST for his stereo! I think he needed 6 circuits or something like that for the stereo???
  9. drick

    drick In the Trades

    Code requires a 20A circuit for dining room outlets. (Dining room lighting - actually all lighting - can be 15A)

    Generally I try to wire two rooms per circuit unless they are large rooms. Seriously, what are you going to really plug in - a TV, a stereo, and maybe a few table lamps. If you have a large family room or master bedroom, put it on its own circuit. If your planning on going crazy with kitchen lighting (some people really do go crazy with the recessed lights, under cabinet lights, pendant light, etc) put that on its own circuit.

    If you want to have all 20A outlets in the house thats fine, there are advantages to it. When the day comes when you want to plug in that space heater or window air conditioner you won't have to give it a second thought. However if you do that I would keep my lighting completely separate and wire it in 14 gauge because your 2, 3 and 4 gang switch boxes get really crowded really fast, especially with some 3 or 4 way circuits thrown in and its not going to be fun to wire that in 12 gauge, plus there is no need for it. Otherwise wiring the lights and outlets in a room on separate circuits is considered good practice but can add to the cost of wire and your time. Its up to you in that case.

    Also as suggested this is the time to pull RG6 and CAT6. Try and keep them a foot away from your other wiring, at least mostly anyway.

  10. Scuba_Dave

    Scuba_Dave Extreme DIY Homeowner

    South of Boston, MA
    One reason I like 20a circuit for outlets
    The vacuum the wife bought is rated at 12a, haven't tested it to see how much it uses
    Her hair dryer uses 1500 watts
    A Plasma TV can use over 500w of power

    When we bought this house I added up all the new circuits I would be running
    One of the 1st thing I did was add a 100a panel 3' to the left of the 200a
    2 years later I had the SF buried & the 200a panel replaced (a little corrosion)
    The electrician wanted to move everything to the 200a panel...plenty of room
    I said no - but he really wanted to do it
    I made a list of all the circuits I was going to add - 8 outside circuits alone
    I finally convinced him that the 100a was staying :rolleyes:
  11. Ian Gills

    Ian Gills Senior Robin Hood Guy

    And there was me thinking lighting had to be on a 15 amp circuit.
  12. frenchie

    frenchie Jack of all trades

    Code reference? I've never heard of that requirement. Can't find it in the NEC (either in the index or in a text search), or find any mention of it on google. And I can't think of a logical reason for it... is it new? (my copy is the 2005, not the 2008)?
  13. Scuba_Dave

    Scuba_Dave Extreme DIY Homeowner

    South of Boston, MA
    The thing I remember if it is considered part of the kitchen
    210.52 does seem to indicate a 20a is required now in Dining rooms ?

    NEC 2008 online for Free:
  14. frenchie

    frenchie Jack of all trades

    Man, it's gonna take forever to get to 210.52 on that thing. No way to skip pages? Times like this, I really wish Mike was around, it's handy having someone who knows the code by heart.

    Anyways... unless they changed it (and as far as I know they didn't) from the 2005... The diningroom is part of the kitchen - so diningroom receptacle can feed off the kitchen's code-required "two-or-more" 20-amp small appliance circuits.

    I read Rick's post, to mean the diningroom needed its own 20-amp circuit.
  15. iminaquagmire

    iminaquagmire DIY Senior Member

    I take it to read that you need (2) 20A receptacles, with both according to 210.12 (B) being AFCI. This is if you are actually on the 2008 NEC. Lots of places have not adopted the AFCI portion of the code either. Check with your local building dept.
  16. drick

    drick In the Trades

    No not its own 20A circuit per se, you can pull it off one of the the kitchen counter circuits if you want. It still needs to be 20A however and I would recommend pulling a new circuit for it. Maybe put the fridge or other non counter top kitchen outlets on it as well.

    Code reference 210.52 B (1)

    Explanation from the handbook:
    Section 210.52(B) requires a minimum of two 20A circuits for all receptacle outlets for the small appliance loads, including refrigeration equipment, in the kitchen, dining room, pantry, and breakfast room of a dwelling unit.

  17. Scuba_Dave

    Scuba_Dave Extreme DIY Homeowner

    South of Boston, MA
    When NEC 2008 opens up look at the bottom right there will be a small icon with:

    That icon opens up an Index where you can go to specific sections

    From what I can read it does not specify a dedicated 20a circuit
    But I would never wire a Dining room off the Kitchen SABC
    I'd add a 3rd circuit instead
  18. frenchie

    frenchie Jack of all trades

    Okay. No disagreement, then. Wasn't sure if it'd changed... seems like a lot of stuff, has. We're updating next year, I think, trying to get a grip on what's coming.
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