Rewiring Knob and Tube in Attic

Discussion in 'Electrical Forum discussion & Blog' started by arfeller, Aug 25, 2007.

  1. arfeller

    arfeller New Member

    Messages:
    77
    Location:
    Port Angeles, WA
    Greetings,

    I am purchasing a home that was built in 1922 which has Knob and tube wiring in the attic.

    1. The House has updated 200 amp service with breaker box (a little small, 20 1" slots)
    2. Has open unfinished basement and nice 2' crawlspace. All other knob and tube has been replaced.
    3. When the other knob and tube was replaced, they did not redo the circuits. I will be rewiring the rest of the house after the knob and tube is replaced.

    So... my question is. All the knob and tube in the attic goes to ceiling lights and the switches. My intention is to rewire all the knob and tube for these ceiling lights and put that on 1-2 circuits

    Is it reasonable to take this approach rather then try to incorporate the ceiling lights into the circuits of each room and outlets?

    3 Bedroom, 1 Bath, 1300 ft2 home.
    If all the ceiling lights were on at the same time ~1500 watts ->12.5 amps
    Also there is bathroom fan, stovetop fan, and ceiling fan. I would put on seperate circuit.

    So two 15 amp circuits to replace the knob and tube.

    Comments?
    Last edited: Aug 25, 2007
  2. Furd

    Furd Engineer

    Messages:
    446
    Location:
    Wet side of Washington State
    I prefer that receptacles and lighting in a room are on separate circuits. This way if you need to work on the receptacle circuit you still have lights and if you need to work on the lighting circuit you may connect a portable lamp to the receptacle circuit.

    I would use at least two independent circuits, more is always better.

    You may be able to use "two-circuit" breakers in your panel which would allow for two circuits in a one-inch space. This is the easiest and least expensive fix.
  3. Chris75

    Chris75 Electrician

    Messages:
    608
    Location:
    Litchfield, CT
    Do a load calculation for the required # of circuits, 3 watts per sq/ft.,
  4. arfeller

    arfeller New Member

    Messages:
    77
    Location:
    Port Angeles, WA
    Thank you all for the responses and Help! :)

    Ok, so here is the calculation

    1300 ft2 * (3 watt/ft2) /120 volts = 32.5 amps

    This is just for ceiling lighting calculation? Or for whole house including outlets?
  5. Chris75

    Chris75 Electrician

    Messages:
    608
    Location:
    Litchfield, CT

    The 3 watts per sq.ft includes receptacles and lighting, (except recess lights and the required bath room receptacle circuit... ) so if you divide 32.5 by 15 you get 2.16, so you would need three 15amp circuits... or two 20 amp circuits...


    You can do what you want with these circuits, but I tend to try and spread them out equally...
  6. xd2005

    xd2005 New Member

    Messages:
    27
    Are you including the basement in 1300 SF calculation? Will that be included as well?
  7. arfeller

    arfeller New Member

    Messages:
    77
    Location:
    Port Angeles, WA

    Good question, it is not included in the 1300 ft2. The unfinished (pretty rough at the moment) basement is ~600 ft2 and would have dedicated 20 amp circuit.
  8. Chris75

    Chris75 Electrician

    Messages:
    608
    Location:
    Litchfield, CT

    The 3 watts per sq.ft. is for livable sq. footage only... the nec only requires 1 gfi protected receptacle in the basement, unless of course you finish it...
  9. frenchie

    frenchie Jack of all trades

    Who upgraded to 200 amp and left you with such a small panel? That must be frustrating... if you start using the double-pole single-slot breakers, careful you don't overfill the panel. They're only rated for a certain number of poles. If you need more spaces than the panel is rated for, consider a sub-panel.
  10. arfeller

    arfeller New Member

    Messages:
    77
    Location:
    Port Angeles, WA
    I'm not sure who, but i would like to have a discussion with them :eek:

    I am currently looking at a siemens 30 1" slot, 40 circuit panel. Seriously debating whether or not to make the change.
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