3-Phase Sub Panel

Check out the Institution of Electrical Engineers' "Wiring Regulations", latest edition. The algorithms needed to calculate cable sizing are within.

What is the sub-panel rated for? 100 amps? 200 amps? Size wire accordingly.

what is the current?or load connected to the sub panel?

Like the commercial says, " Do not attempt this at home." If you've got to ask that question, call an electrician.

Absolutely!!!!!

The fact that you are asking means you have no business messing with this. Is the cost of a qualified electrician worth the life of your family?

what is this my friend!!! this is not an electrical engineer question

we need more information ( load which will be fed by this panel , the distance between the power supply (which feeds the panel) and the panel itself.

regards

Bill is right for the most part. Size the wire based on the individual breaker feeding the sub-panel. Then select the insulation you need based on the environment.

Good luck, James

I must agree that due to the lack of information you should seek professional assistance. Now, this professional should the regs set forth in NFPA 70, otherwise known as the National Electrical Code -NEC-

There are many articles that need to be considered for you job including:

Art 250 grounding, Art 300 Wiring Methods, table 310-16 Conductor size, Art 230 services, Art 240 Overcurrent Protection, Conductor Fill etc.

Happy wiring!

The King

If I may make an observation, as a friend. I detect, the quality of your English may vary from comment to comment. You are not playing a joke on us are you?

James

Balance the loads on the phases so as to not make the neutral hot. Some call the neutral backfeed. Add up Watts for each line so they will balance out to same Amp feed capacity at maximum draws. Bigger is better. Typically service bus bar power boxes come in 100, 200, 300 Amp service panels for homes. Most home plugs are rated by themselves on the circuit for 15 amps. Kitchens may have 20 amp circuits, and then a 220 feed on 30 to 50 amps to something like a stove.

Nomenclature for residential wire is not my forte, since I used 80 amp #2, and then 2 ought through 4 ought on film set lighting.

If you are inexperienced, and doing it all yourself for the first time, I suggest as well getting some help.

Always either dead or alive get into the habit of attaching ground first, neutral second, and then hots, and detaching in reverse order, hots first, then neutral and last ground, and you will live with AC.

Square D boxes and Cutler Hammer Boxes are better than the Seimens Boxes I've tied into since they allow room to work, and the Seimens Bus Bars are fragile and close to hots.

It is said that a pic is worth a thousand words...

What exactly caused the explosion? Thanks for photo. Hope no one was standing infront of flash.

My 350hp ammonia compressor motor went phase to phase internal and tripped off it's feeder a couple of days before this mccb failed. I'm sure the fault current degraded the contacts or weakened the springs in the older 1200 amp molded case main. Contact resistance went way up resulting in thermal runaway. Came in for plant start on a Monday morning to find this mess.

I did a bunch of years doing emergency power gen controls and switching and have seen more than my share of these kinds of messes. I've seen many messes occur where the person installing system additions did not truely understand the dynamics and force of electrics and ended up undersizing cables.

As said above ... if one is unsure about cable sizing, xfmr kva rating, etc etc, get a professional involved. It is usually a lot less messy in the long run.

Wires considerations depend upon current carrying capacity with voltage and load , you have to be specific about fuses and mcb`s that should match load conditions accuratly for safety and protection for your accessories and you

Just use a couple of #12 AWG or #14 AWG Wire and that should do it

Actually you should size the conductor based on the load. Then size the breaker per the NEC which I can assure will ensure that the breaker trips before the wire burns into and starts a fire. The main purpose of the NEC is safety. Safety for the workman as well as for the operator of the system. I respect everyone's willingness to jump into the frey and provide answers; however, it is obvious that the person asking the question is not qualified to do the work. A 120/208 y system is a fairly easy three phase system to work with. No "wild" leg, etc. to contend with. Quite a few of the answers, probably the majority of the answers, given here addresses the theoretical and not the fact that this guy needs to call a professional before he kills himself or the first poor sap that has to work on his mess. I've seen similiar situations like Switchman's picture and I've also seen the freshly burned imprint of a human hand on the cabinet door. There is a time and a place for everything and this is not the time nor the place to advise this person to do this project on his own.