GFCIs in the service panel? How many circuits?

Discussion in 'Electrical Forum discussion & Blog' started by bobwilli, Nov 23, 2009.

  1. bobwilli

    bobwilli New Member

    Messages:
    10
    Location:
    Salem, Oregon
    I am planning to upgrade my collection of old electrical panels in my 1948 home to a single 200A panel. I have screw-in fuses and some breakers. I have been told I can convert my 2-wire outlets to 3-wire if I install GFCI breakers on the dircuits in the new service panel. Is this true? Is it wise?

    Are there circuits I should not put GFCIs on?

    Another question, to know how much this will cost I need to know how many circuits I have. How do I tell from the panels I have now?

    Thanks!
  2. Jeff1

    Jeff1 New Member

    Messages:
    102
    Location:
    So Cal
    Cost is based on what you will have done and if you will do it yourself (not recommended) or have a pro do it. Many years ago I paid $1500 to have a new 200A panel installed and feed my original panel as a sub-panel. Its worth every penny to know its done correctly and up to code since a mistake there could cost your home or a life. Let a pro see your current setup and give you a quote. I strongly recommend a licensed pro and a permit for the work.

    As far as GFI in the panel, its up to you how you want things to work. Circuits for appliances like refrigerators should not have GFIs on them. Any circuit that will be in the bathroom or kitchen and will be for outlets should be GFI.

    There is more to upgrading your outlets to grounded than simply adding the GFI. How is the wire being run now? Is it in conduit? Grounded outlets are great to have especially for computers and other equipment that requires a ground. I'll let the pro's take it from here.
  3. Thatguy

    Thatguy Homeowner

    Messages:
    1,459
    Location:
    MD
    900' of Romex or 20 ea. 45' lengths, will trip a 5 mA GFCI due to interconductor capacitance in the cable.
    Last edited: Nov 23, 2009
  4. bobwilli

    bobwilli New Member

    Messages:
    10
    Location:
    Salem, Oregon
    How do I tell how many circuts there are?

    I will have the panel work done by a pro, but I was planning to change out the outlets myself. Is that advised?

    One contractor gave me a price per GFCI, so I need to know about how many circuits will be protected to estimate what the bid will turn out to be. How do I tell from my panels how many circuits there are to protect?

    Thanks!
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,274
    Location:
    New England
    Each fuse or circuit breaker is a circuit, with one possible exception on 220vac circuits. A 220vac circuit needs two fuses, but they should be tied together in some manner. You may not have any. An electric dryer, stove, WH, and possibly other things are likely 220vac. Those are probably now on circuit breakers, but could be on a double fuse assembly. In the USA, in a residential setting, your power coming in is actually 220vac, but the neutral is half-way across the transformer that feeds the house. So, from neutral to one hot is 1/2 the voltage or 110. If you need the full voltage, you use the hots from each side of the transformer, which gives you the full 220vac. If you mess up and get two hots from the same side of the transformer, you'll have zero volts, but it's still 110vac if you measure it to ground. Ground normally should not have any current on it.

    Yes, you can install a grounded recepticle IF you mark it as GFCI protected, no ground. Note, some things really want a ground. They usually include the stickers in the box. If you use a standard circuit breaker and install a gfci outlet in the first box of the string, feed the downstream outlets from the load side of the GFCI, then it will do the same thing, and may be easier to reset if you trip one - you'd do it in the house rather than having to go back to the panel. But, knowing WHERE the GFCI tripped could be a pain. It's easier if they're all in one place. A GFCI recepticle is less expensive than a breaker.
  6. Alectrician

    Alectrician DIY Senior Member

    Messages:
    689
    Yes and yes



    Maybe the refer/freezer. The kitchen is one area you may want to use GFCI receptacles. This creates it's own challanges because the old boxes are often to small to house a GFCI recep and must be changed.

    The problem is they made a habit out of running circuits thru the ceiling jboxes in this era and you can't get to the first stop.


    GFCI breakers are usually the way to go and they only add abour $30 a piece to the cost.

    Count your existing fuses and you will know appx how many you need.

    Depends on what shape the wiring is in. Disturbing old wiring can cause issues. It would be best to have the electrician look at it. If it's in good shape, it aint rocket science. Wrap your wires clockwise with white on the left, black on the right (ground down)

    Note: If you have any 3 wire homeruns, GFCI breakers will not work unless you can put both circuits on one breaker. A red wire leading to a breaker is an indicator of a 3 wire home run.
    Last edited by a moderator: Nov 23, 2009
  7. bobwilli

    bobwilli New Member

    Messages:
    10
    Location:
    Salem, Oregon
    What's a "3-wire homerun"?
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,274
    Location:
    New England
    A 120vac circuit needs hot, neutral (and ground). Since neutral is tapped off of the middle of the transformer, if you use a 3-wire cable, and run one end of the transformer (say the black) lead to one set of circuits, and red to the other, since they are on the opposite sides of the transformer, the current that comes back through the common neutral essentially cancels, and instead of running two 2-wire circuits, you can provide two of them with one 3-wire circuit.

    A GFCI works by measuring the difference between the hot and neutral. If it differs by a small amount, it will trip. On a 3-wire circuit, you are unlikely to have totally balanced loads on each leg, so the current between each hot and the common neutral is almost certainly not going to be equal. So, the GFCI would trip. To run those, you need dedicated hot and neutral on any GFCI circuit, you can't share it like you can on a 3-wire circuit.
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