On Wed, Mar 16, 2016, at 01:26 PM, Todd Zuercher wrote: > Bringing back an older thread. Went to start ordering the things I need for > the update and noticed that the conduit to the machine isn't big enough for > the new wiring. Right now the 9 single phase circuits are run through two > 3/4" conduits (4 in one 5 in the other). would it be a really bad idea or > against regs, to split the 3ph wiring between the 2 conduits? (2+ground in > one and 1+nutral in the other) >
Don't do it. Whenever you have a wire taking current to a load, the return path(s) for that load need to be in the same conduit. That means all three phases of a three-phase load, or phase and neutral for a single-phase load. The reason for this is that if both (single phase) or all three (three phase) wires are in the same conduit, the net current is zero and thus the magnetic field around the bundle of wires is zero If you don't have all the wires in one conduit, there is a net magnetic field, and it can induce circulating currents in the conduit. Even without conduit (or with plastic conduit), if you have un-matched cables running through holes in a steel enclosure wall you can induce eddy currents in the wall. At modest current levels you can get away with it, but it is bad practice. At high current levels the induced currents generate heat, and you can melt things. Regarding grounds - codes usually require that ground wires run in the same current as the load carrying wires. Putting the ground in another conduit adds inductance (due to the loop area formed, and aggravated if the conduit is steel). That inductance increases voltage drop and makes the ground less effective in the event of a short to ground at the load. -- John Kasunich jmkasun...@fastmail.fm ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785231&iu=/4140 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
