240v - adding new breaker, 4 wire problems

[mashweasel]

Boys,

Im needing to swap out an old 15A dual pole 250v breaker. I want to put in a 20a breaker. The likes are all 10g so they should hold the amps fine.

What Im having a problem with is the lines change from 3 to 4 wires and back again. There will only be one receptacle on the whole line. Here goes my explaination:

1. Only 3 wires coming in from the conduit to the electric panel. 2 purple (hot) and 1 orange (neutral). There is no ground for this circuit. I havent seen this before. Is it a problem.

2. Im closing an old receptacle in a junction box that contained a locking type 15a receptacle. This had 4 wires, 2 hots, neutral and a bare ground tied to the box. Ive ran all my new wire after connecting the junction box ones with wire nuts. The new 20a 250v receptacle (NEMA 6-20A) and matching plug, only have three screws. Two hots and green green. Whats up with the neutral? Where does that go?

3. The coffee machine that Im putting in requires 250v, 4 wires. So if I get 12-4 shielded cable Ill still have the one neutral to put into the plug that doesnt have a spot for it (see above).

I can provide pictures of anything you guys need.

Thanks a ton!

[suemarkp]

You have some major problems. First, if the coffee machine requires 250V, 4 wires, then it better not have a 6-20P (they don't have provisions for neutrals as many 240V appliances odn't need neutrals). You'll need the correct 4-wire 125/250V plug and receptacle. This will have 4 screws for the 4 wires you need. Or is this a 3-phase coffee machine that wants 3 hots and 1 ground???

Next, neutral wires sized at #10 must be white. Neither purple nor orange can be used for a neutral nor are you allowed to recolor pulled wires.

Are you sure there is even a neutral in this circuit? Orange is normally a high leg on a 3-phase delta system. It is possible you have 3 hots, no neutral, and a conduit for the ground. You need to measure the voltages here to see what you've got.

It may just be better to start over. Pull a white neutral, and I prefer a separate ground unless you sure the conduit is well made up.

What kind of cable are you calling "shielded cable". Do you need an appliance cord? If so, use cord (SJ, SEO, ...). If this is hard wired (no plug), then you can use AC (armored cable) or MC (metal clad) cable.

[mashweasel]

4-wire 125/250V plug and receptacle purchased and took care of all the down stream problems.

100% for sure the conduit running into the electric panel are 2 purple and 1 orange. They seemed to have been using the conduit as the ground but did not run it into the box. So it seems it might just be easier just to re-run the 50 or so feet of 12-3 romex in conduit than to eff about with the purple crap. Yes?

If I do run the conduit, can I use the grey pvc? Ive used it for 120V a lot but dont know if I can for 250V.

[joed]

If you do run conduit, do not run 12/3 NM cable. Buy the proper #12 thhn wires and pull them into the conduit.

[suemarkp]

There is no limitation on PVC conduit at 250V. You just have to treat it like it is romex unless you run schedule 80 (sch 80 can be exposed to physical damage whereas romex and sch40 PVC can not).

Whether you can use PVC depends on your building code. For a residence it is fine. Some commercial occupancies have bans on PVC wiring methods.

[mashweasel]

Is there any reason not to run the 12-3 romex other than price?

[Mr T]

Code not allowing it would be a very good reason. Commercial settings are much more strict then residential.

If you are planning on pulling it through a conduit it could take a few years off your life, raise your blood pressure, and cost you alot of your hair. It is VERY hightly recomend you dont pull a cable through conduit.

[mashweasel]

Very good then!

Ill get the #12 thhn wires as suggested.

For future reference, why would code not allow romex through conduit? It seems to me that romex just puts everything together so its easier, no?

FWIW, the new romex with the 'special' coating seems pretty easy to pull.

[suemarkp]

Romex is allowed in conduit, but romex may not be allowed at all in your building (if wood stud construction is allowed for this building, romex should be allowed as would PVC conduit). To pull romex through a complete conduit system, you have to treat the cable as an individual wire when it comes to conduit fill. A 12-2 romex cable is about the same size as a #2 or 1/0 wire when it comes to fill, so don't be trying to pull this through a half inch conduit.

[mashweasel]

Got it. So Ive only got about 50' to pull. If Im pulling 4 wires shall I get the 3/4 conduit or can I stay with the 1/2?

[suemarkp]

For four #12's, half inch is plenty (can have 8 #12 THHN in sch 40 PVC, and 6 in sch 80 PVC).

[mashweasel]

Thanks guys. Everything worked our great. 240V working like a dream.