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    jomaycan's Avatar
    jomaycan Posts: 2, Reputation: 1
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    #1

    Jan 19, 2009, 06:35 AM
    Overload sub panel
    We are renovating an old house and have converted it to 3 apartments. We had a 200 amp panel in the basement and a sub panel on the first floor. WE have been upgrading the wiring (most of which was knob and tube) and we have added new wiring to the sub panel box. The problem is that half of the fuse (that is feeding the sub panel) in the main panel is blowing every so often. I assume that we have too much load on the sub panel.

    I am not sure if transferring some of the load to the main panel box will do any good because they may then overload the main panel.

    I thought I would try this route before I call in an electrician.

    I am not sure just how much a 200 amp can handle. Obviously , not all amps are being used at all times.
    donf's Avatar
    donf Posts: 5,679, Reputation: 582
    Printers & Electronics Expert
     
    #2

    Jan 19, 2009, 07:12 AM
    You can probably get 205 +/- amps on the breaker before she opens.

    These are Over Current Protection Devices.

    None of that matters because you really need to get an electrician in to design and install adequate wiring for your needs.

    You are more than likely violating a whole raft of codes because you are not supplying enough power to the building not to mention that each apartment should have its own meter and panel and common areas should be on their meter and panel.

    One thing you might find to your advantage is to correctly size your load requirements and then plan your circuits.

    You do have a permit, don't you? Does your LAHJ allow unlicensed electricians to pull permits and wire an "Apartment Building"?
    Did your power company approve upgrading to 200 Amps for the entire building knowing that your plan design was to power three separate apartments from the one meter?

    Please consult an electrician an at least get the benefit of his/her knowledge of building and electrical codes to calculate necessary load and plan required circuits!
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #3

    Jan 19, 2009, 09:38 AM

    Donf makes LOTS of good points.

    Breakers have a time-trip curve. They should be able to withstand the rating forever. The higher the overload the faster it trips. For instance, a refrigerator, which comes on randomly may be enough to push it over the edge.

    200/3 is a bit too small per unit. I don't know if the units are mostly electric or gas. That's a little over 65A per unit.
    A toaster, hair drier, a fridge and about 20 A left over. Not a whole lot.

    The AHJ may have minimum requirements for apartments.
    21boat's Avatar
    21boat Posts: 2,441, Reputation: 212
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    #4

    Jan 20, 2009, 02:07 AM
    Quote Originally Posted by ;
    I assume that we have too much load on the sub panel.
    Well for what its worth as an apartment building owner of units I don't quite understand why you didn't want to zone out the units to begin with so they can pay there own electric. Just to give you and Idea on basic loads. A microwave needs to be on its on dedicated circuit for the magnetron to be supplied and no drops in power. The fridge should be on a 20 amp. The kitchen should be on a 20 amp. The bathroom also 20 amp. Think about it, This is an old building and I doubt it has central AC. So when a tenant wants to put in a window AC and keeps tripping breakers then what. What I did in my old units is make sure one window had a dedicated 20 amp there for the AC. I as a landlord did not want to go through the calls that the breaker tripped and can I reset it. Sorry it just seems you are trying to get by here and cut to hard of a corner. Old houses had 60 amps and the 100 amps and 200 amps. The new appliance's are a lot and heavy. The didn't just build more power plants because of population growth. It's the Electric accessories that built many plants. So the apartment building the same thing. Knob and tube to 20th century. Sorry I wrote a lot here but think of what I said and what you are trying to do bare bones. In answer to your question you already answered it look at the quote above. Basic amps per unit is 100amps bare min for this era and by code where I come from. I'm not trying to give you a hard time it just seems like you are creating a big problem not zoning out the power supply properly
    jomaycan's Avatar
    jomaycan Posts: 2, Reputation: 1
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    #5

    Jan 20, 2009, 08:26 AM
    Overload sub panel
    Further to my first question I should clarify some things.

    First of all, the sub panel was all ready installed , we just moved it and added to it.

    Secondly, this building was commercial and once housed a hardware store so I assumed that 2 panel boxes would suffice.

    Our 3 apartments were not for gain, we have our 2 mothers with us and we wanted separate living quarters for each of us.

    I do not want to put in 3 services because it costs 3 separate base charges which we don't need and we all ready have a 2nd service in the garage ( which was also here when we bought the place).

    The garage is not attached so it would be a bit difficult to reroute some of the load to the garage service which is hardly used at all.

    I just wondered if there was any other alternatives to this.
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #6

    Jan 20, 2009, 08:44 AM

    <Threads merged>

    Don't start a new thread on the same topic. Continue with this one.
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #7

    Jan 20, 2009, 09:20 AM
    Some commercial properties, such as yours don't need much. A hardware store has lighting and HVAC.

    Doing an actual load calculation, by figuring out just what appliances are used etc. would help you size the service.

    To avoid another "base charge" have the service upgraded to 400 Amp.

    Midwest Electric Products, Inc. has some interesting SE meter panels. For instance 400 A service, with two 200 A mains and 8 additional circuits.

    Usually the max breaker size is limited to 100A for a standard panel.

    So, you could do a 100, 100, 200 and you might make everyone happy. You could take the 200 and create a common zone sub-panel.

    Sometimes load-sheading can work, or it can mean training, Like: you can't have microwave, toaster and curling iron on at the same time.

    You can sub-meter and have instant power consumption displayed, so you know what the loads are.

    It would be wise to tabulate the loads in any event. Any load that's may be on for three hours or more is classified as continuous and it's load multiplied by 1.25. Space heating is considered continuous.
    donf's Avatar
    donf Posts: 5,679, Reputation: 582
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    #8

    Jan 20, 2009, 10:30 AM
    Please understand, we are not trying to pound you into the ground.

    You must take some time and go over the building codes and electrical codes.

    What you are defining as simple consideration in your mind, may in fact be defined by code as something else.

    For example, what are you going to do when one or both of your mothers either pass away or need to be placed in a home for their own safety.

    My logic says you would consider renting the apartment to a tenant. Because of that option, you have to do the planning correctly.

    I cannot speak for all electrical contractors, in fact I can't speak for any contractors, but I have been able to get a reduction in labor costs if I agreed to do most of the Scud work myself. Two benefits, 1) I got to learn how to do things correctly and 2) I saved a little money, but the work was done to code and passed inspection.
    21boat's Avatar
    21boat Posts: 2,441, Reputation: 212
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    #9

    Jan 20, 2009, 11:39 AM

    Not be off the subject and not trying to start another thread but this information could completely change the original thread as to having a whole another approach.
    jomaycan
    If you are moving into the building and are trying to save money and I don't know if anybody here realizes this but that meter could still be on commercial electric which is double the cost for kilowatts for usage which gets very expansive real quick in running cost and would completely offset the meter base cost. I personally went through this already in reverse on a salon attached to a city home. So check that out and see if the commercial base was down graded to res. That's how Pa Power and Light company works.

    Signed 21 Boat

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