power for an oven

mx842 · Mar 3, 2017

CobyRupert said:
Now I'm even more confused on what you have.

(1)- 10,000 Watt burner (3 tube) or (3) - 10,000 Watt burners? That is, 10,000 or 30,000 Watts of load?
By burners, I think you mean elements?
If 3 elements, do all 3 come after the re-wire? Sounds like only 1 does, so your load is 10,000 watts?

Even then, it really wouldn't be 10,000W, I mean:
Are you running these (208V) elements on 240V single phase? (i.e. people rarely have 208V single phase and not 208V 3 phase). That is a 10,000 watt/208V element will output a lot more wattage if run at 240V, and a lot less if wired line-to neutral (120V). Current draw is also dramatically effected.

Are the element(s) wired line-to-line, or line to neutral?

Yeah I can do that sometimes.:laughing: 1 burner = 3) 3500 watt tubes rated at 10000 watts total. Each burner has 6 stud connectors for one in and one out. Basically each burner has 3 separate tubes with wire connectors on each end that are connected together with a bracket.

I'll see if I can find some pics if not I'll take some and post them.

The way I wired it is each tube, (9 in all, 3 each burner) has 1, 10 ga wire coming into the tube and 1, 10 ga wire going back to the control box. Each 3 tube burner has it's own terminal board in the control box and each burner has it's own contactor relay. I had a 125 Amp service panel over top of the control box that fed the control. I had it set up where every relay was on it own 40 amp breaker in the service box.

When I did the test run I fed the service panel with a 10' long, 4 conductor 8 ga cord, that had a 50a 4 pin plug. The plug was plugged into the existing 50 amp pug that fed the old paint booth.

I don't know if this helps you understand this mess I have any better but if not I'll try again.

CobyRupert · Mar 3, 2017

Lots of variables/ And we know none.

What feeds the 4 wire plug? 240V, a neutral, and a ground?
You have 3500 watt tubes, I assume that is their 208V rating?
How are the 4 wires from the receptacle distributed among the tubes? If it was previously 3 phase, 1/3 of the tubes may be running at 240V, and the other 2/3 may be running at 120V.

(A 3500 Watt tube rated for 208V is a 4660 Watt tube when run at 240V, and it's a 1165Watt tube when running at 120V.

Bottom line: Given that nobody knows much; for safety's sake, I'd suggest that the ampacity of any wire that you use is greater than the ampacity of any breaker you use. That way you hopefully won't melt the wire.

mx842 · Mar 5, 2017

CobyRupert said:
Lots of variables/ And we know none.

What feeds the 4 wire plug? 240V, a neutral, and a ground?
You have 3500 watt tubes, I assume that is their 208V rating?
How are the 4 wires from the receptacle distributed among the tubes? If it was previously 3 phase, 1/3 of the tubes may be running at 240V, and the other 2/3 may be running at 120V.

(A 3500 Watt tube rated for 208V is a 4660 Watt tube when run at 240V, and it's a 1165Watt tube when running at 120V.

Bottom line: Given that nobody knows much; for safety's sake, I'd suggest that the ampacity of any wire that you use is greater than the ampacity of any breaker you use. That way you hopefully won't melt the wire.

Four 6 ga wires, 240 with ground and neutral.

The tubes I bought had a 208v/240v rating.

Each contactor is fed by a terminal strip, with it's own thermostat. Thermostat calls for heat and sets off the contactor which sends current out of the bottom terminals on the contactor to, two other terminal strips one for the red wire one for the black. Well it's one strip that has two sections, one for the red wire one for the black. Each burner has 6 wires going to it from these strips, current goes in one end of the tube and out the other end back to the terminal strip. same for the other two tubes in this one, three tube heater kit.

There are three, 3 tube burners in all, each has it's own contactor, thermostat, terminal boards in the oven. Basically three different circuits that work together. I set it up so that once the oven got up to temp one of the burners would drop off and not come back on unless needed.

I don't want to melt any wires but when I tested this thing I ran it off one single 50a plug in circuit and it worked just fine. Not saying that this is the right way to do it I'm just saying that's how it went. I knew when I tried it that it seemed to me to be too much to ask of this one 50 amp plug. I fired off one burner at a time until they were all working then kicked on the lights and fan unit until it got up to temp. What's strange is that nothing seemed to get hot or warm even the whole time I was running it for the test.