wire color code isolation transformer single secondary color code

Is the transformer outside? Choose Scenario 2. To pick the right one, answer three easy questions: Scenario 5: Secondary conductors 10 to 25 feet long, industrial installation. Scenario 4: Secondary conductors 10 to 25 feet long. Scenario 3: Secondary conductors not over 10 feet long. Scenario 2: Outside secondary conductors. Scenario 1: Secondary conductors from a feeder-tapped transformer. That same tip applies to transformer secondary conductors, which also have five scenarios. We also described an easy way to pick the correct scenario from the five possible. When we demystified feeder taps in the previous issue, we presented the information in an arrangement that differs from what you see in the NEC. As with feeder taps, the sizing of that transformer secondary conductor depends on its length and application. The rule is the same because the physics are the same. Normally, you can use the next highest overcurrent protective device (OCPD) above the ampacity of the conductors being protected, but not with transformer secondary conductors. Basic rulesĪs with feeder taps, you can't use the “next-size-up-OCPD” rule provided in 240.4(B) for any transformer secondary conductor. Let's take a closer look at 240.21(C) to help clear up any misconceptions. Hopefully one of the experienced builders here with proof what I've written and correct me if I am wrong.īest Wishes and Good Luck with the build.Similar to feeder taps, covered in the last issue, transformer secondary conductors can be every bit as confusing. Getting the wiring correct, with respect to the layout and schematic is essential. Probably both of the 120v primary wires on the PT are black. NO other ground wires of any type should be connected there! That connection should be a short stout wire gauge securely fastened (bolt, very tight) to the chassis near the power socket.

On the power socket, the 'E' (green wire on the layout) is Earth Ground. Notice where the other side of the MOV (mentioned above) connects to the front panel power switch? That's where the other 120v primary wire of the PT goes. That gets connected from the power socket to the power switch at the point labeled C2 on the layout (again, use color coded wire to keep things organized).

that's the switch lug (left side of switch) the hot side of the PT 120v primary goes to.īack to the layout, the 'N' on the power socket is the neutral line (0 volts). See the MOV (metal oxide varistor) on the layout. From the power socket, the live wire goes to the fuse (I suggest using color coded wire here to help keep things properly identified), and then to the front panel power switch (labeled C1 on layout).įrom the power switch the live connection goes to the power transformer primary (120 volt side of HTS-5199 diagram). On your layout, the hot wire from the wall power is labeled L (in red on the layout).

Wire color code isolation transformer single secondary color code