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3 phase panel board

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  • 3 phase panel board

    Looking for a 3 phase panel board (breaker box) for some new wiring I'm putting up. I dont need one of the huge ones just a smaller unit if possible. If you have one laying around send me a PM...gear
    Senior Member
    Last edited by gearhead; 05-27-2009, 03:50 PM.

  • #2
    Go to They have 3 phase Square D 12 circuit panels including covers for $89 plus shipping. The panels has enough slots for four 240 volt 3 phase breakers and come with 125 amp main lugs.

    Three phase breakers, 240 volt, are $55 each. This is new equipment and comes in factory sealed boxes.

    To get info on their load centers call their 800 number. Very fast and reasonable shipping.


    • #3
      You might want to check flea markets and swap meets. Used three phase panels can be found cheap and usually with some breakers. Commercial Electricans often have used ones from panel changeouts.


      • #4
        Thanks for the information. May have found one on Craigs list for $50.00. No breakers though. Looks like three phase breakers are very expensive. I'm running just a couple of smaller three phase machines. Just need some 10 or 20 amp breakers to get by. gear


        • #5
          That's the beauty behind finding a used one pulled out as scrap, or from an industrial or light commercial building about to torn down. The breakers are worth more than the enclosure. The building demo. guys only want the saleable copper, brass, etc. Try to stick with a known brand like Square D, most 3 pole breakers are bolt in, snap in 3ph. panels are less common.


          • #6
            Just by chance the breaker box is a Square D, 24 or 26 breaker box. Very good condition. But your right, I expect to pay $75.00 per breaker. Luckly I only need two or three to start off with...


            • #7
              Is everyone putting somekind of fuse box or the like to protect the equipment motors from a current spike. I believe it is call overload protection or thermal protection. I have been told it is not necessary for the hobby guy and then I have also been told you have to have it in place to save the motor. ???? In my case I operate one machine at a time and if something happened it could be quickly turned off. Is this protection for the production type of operation.
              Senior Member
              Last edited by gearhead; 06-01-2009, 08:40 PM.


              • #8
                Breakers protect only the wiring in the wall.

                The overload protector keeps the motor from being fried (when properly set).

                For motors over 1 HP or so, they are really required by the NEC, and are a good idea anyway. No fuse has the characteristics of the overload protector, which will trip on a long duration small overload, OR on a higher and shorter duration, both. Always according to settings, of course.

                Keep eye on ball.
                Hashim Khan

                Everything not impossible is compulsory

                Birds are NOT real, they are spying on you


                • #9
                  I have been looking around for the motor starters (overload protection) prices aren't to bad. Looks easy enough to install too.


                  • #10
                    As mentioned above, breakers are to protect the building from fire caused by short circuits and other heavy currents in the wiring and devices/loads connected to the wiring. Thus, breakers are at the entrance to the building and in larger installations in sub panels located around the building. There is seldom any reason for locating a breaker at a machine or other electrical load. I have seen large, complicated machines that effectively had their own sub panel built in, but we are not talking about that situation.

                    At each device/load there should be a positive means of disconnecting it from the electrical supply to allow work to be performed on it in safety. Most small devices with cords and plugs can simply be unpluged to satisfy this requirement. Larger machines, like central air conditioning equipment, large blowers, and three phase machine tools must have some kind of disconnect. Again, a plug is acceptable, but often a "disconnect" box is less expensive and easier to install. A two or three pole switch is sometimes seen on such equipment. Sometimes breakers are used as this switch and this may be what gives the impression that breakers should be installed at the epuipment. I believe this is also acceptable under the code but I personally prefer an external device so that the power never enters the machine for complete safety.

                    Additional protection devices to protect a motor can be installed, but are not required by the NEC (National Electric Code). Such devices may or may not include the required disconnect device. If the particular machine does require such a device it will probably be designed into it.

                    Short term spikes in the electric lines are not a threat to most motors. They are just too short to contain enough energy to damage these relatively large lumps of metal. However, they can easily damage electronic devices (the active part of transistors, ICs, etc. are only a small fraction of a gram in mass and can heat up to vaporizing temperatures with very small amounts of energy) so if the machine has any electronic controls they may really need spike protection.

                    Longer term surges, minutes or hours, may damage a motor but are relatively rare. Unless you are located in an area that is prone to such surges, I wouldn't worry about them. Most problems with the electric distribution network are either short term spikes or decreases in the Voltage due to heavy loads or accidents.

                    Decreases in the Voltage or "brownouts" can also be damaging to motors as they may stall and overheat. However, this is a long term condition and you can simply shut the machine down if you see the lights dim. You should also shut down any air conditioning units and any other things with motors if you experience a brownout.
                    Paul A.
                    SE Texas

                    And if you look REAL close at an analog signal,
                    You will find that it has discrete steps.