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Today, at my friends place of work I noticed they had a newly installed electrical panel with a set of cam-locks installed: Black, Red, Blue, White & Green, thus three phase power. (It had 3 and the phase symbol on the panel).<p>Inside the panel, they had a 220V line ran in, and jumped the black leg too the third leg of the "three phase" setup.<p>Is this right, the way its connected? There is no phase converter involved.<p>Thx

No, and very probably the phase common to two poles will eventually be overloaded.<p>At the end of the day, the National Electric Code requires apparatus to be installed as intended, either by the manufacturer's instructions or the UL listing. This panel, as installed, does neither.<p>[ June 26, 2005: Message edited by: rstofer ]</p>

In the heavier wire (cables), roughly #8 size and larger, colored wire is not usually available, just black. Convention is to use colored vinyl tape (just like the usual black electrical tape but colored) to mark the cables inlieu of colored wire full length. For 220 (actually probably closer to 240) volt you should have a ground wire, either bare or green, a neutral marked white, and 2 black unmarked wires. Votage should be 240 between the 2 blacks, and 120 between the white and either of the blacks.<p>I'm not 100% sure, but 3 phase should have (in addition to the ground wire) 3 wires, a black, red, and blue. There are several methods of generating (either generator or transformer) that can create different readings, and wire markings, but not unusual to be able to get 120 or 220 volts single phase from the part of the wires available.

The colors (red, black, blue, white, green)are on the cam hoods and inside the panel is red, black and white (with grnd) which is 220.<p>This panel is used to connect into a distro unit that supplies 110 Uground and 220 T-Loc.<p>The system is installed in the warehouse and only for testing, not running at full capacity for long periods of time.

Sounds like 'they' had a 3 phase panel they wanted to pawn off on somebody. By putting that jumper in ,all breaker slots will work, just not 3 phase..

3phase is 208 line to line 120 line to neutral or 480 line to line 277 line to neutral 3 phase is 120 degrees apart phase to phase 240 single phase line to line 120 line to neutral the 2 lines are 180 degrees apart...so the panel maybe for 3 phase service but is wired for single phase 240
joe

It sounds like they are trying to utilize an improper panel to save a buck. In effect, 2/3 of the breakers will be feeding off of one of the 110v lines and only 1/3 of the breakers off the other 110v line. This is rather inefficient, as they can safely only use this panel to 66% of it’s capacity no matter how they distribute the loads. For safety, they might as well not jumper that “black” feed to the “blue” buss-bar and leave those breaker slots unpopulated as well. <p>Clearly, this method is just a bad way of distributing single phase 220/110. If they need 3 phase at a location where only single phase is available, it can be generated locally via a Scott-transformer(large scale) or electronically via a programmable motor controller(small scale), albeit with an ugly sine wave.

The power is used to power a lighting system that contains three dimmers.<p>Is it possible the three phase supply is used at 3 seperate circuits? ie black/white, blue/white, red/white....?