1 phase to 3 phase

N

NB jr

New User
Location
Kansas City MO
Occupation
Electrician
Hello I’m looking for some sort of guidance here. I mainly do residential so never really work with 3 phase. I have a customer with a 3 phase oven (Model: E101-E Duke) 208/3phase 10kw. She has it in her garage and that’s where she wants to run it. I have the availability to get power there but there is a 8/2 there already.

Is it possible to convert this?
 
Duke Ovens are easy to convert to single phase 240 but you may want order a '240V' element kit.
You change the taps on the elements, there is a diagram in the oven by the control panel.
Your AHJ may require a new nameplate
You'll also probably need a larger cord NEMA 6-50.
 
1) You don't want to convert single phase to 3 phase to run an oven. Do as posts #2 and #3 describe, and convert the oven to run on single phase.

2) What sort of 8/2 is already there? 8/2 NM or 8/2 SE or something else? Does the 8/2 have an EGC? It is a stretch to push 10kW through an 8/2 NM, but demand factors apply to residential ovens.
 
This is all correct. Convert the heating element to single phase. This might change the dynamics of heating, but it will work.
 
NB jr said:
Hello I’m looking for some sort of guidance here. I mainly do residential so never really work with 3 phase. I have a customer with a 3 phase oven (Model: E101-E Duke) 208/3phase 10kw. She has it in her garage and that’s where she wants to run it. I have the availability to get power there but there is a 8/2 there already.

Is it possible to convert this?
Click to expand...
Converting the oven from three phase to single phase: Yes, probably; see other posts in this thread.

Converting the feeder or branch from single phase to three phase: No.
 
I just took a peek at the parts list and schematic.

This oven is available with 208, 240, or 480V heating elements.

The schematic shows how to wire it 1 phase or 3 phase. That looks pretty simple.

I would advise against running the 208V elements at 240V.

-Jonathan
 
I think we are really discussing two things changing the phase and voltage.
Presumably the oven is just a fixed resistor, possibly also a small blower fan
If the OP has a 208 single phase service and was converting the oven to 'single phase' via changing internal taps
but voltage stays 208 single phase:
10000W/208V = ~48 Amp load
and it still be a 10 kw oven.
Since its basically a resistor the ohms would be E2 / P
= 208^2/10000W
= 4.33 ohm load
So at 240V single phase it would draw
I= E/R
240/4.33
= 55.43 amps.
= 13.3kW oven
 
winnie said:
Yes, with the 240V heating elements. If you use a 208V unit at 240V the current will be higher.
Click to expand...
Well sure, but I don't think anyone suggested that he do that. The 240V elements are a separate part which he'll have to order.

46 amps on 8/2 NM-B (if that's correct) would be another problem.
 
Reconfigure element connections for single phase and connect via proper buck/boost transformer to get rated input volts.

Per note 5 in T220.55 single oven like this has branch circuit load the same as appliance rating so you can't apply demand factor to the branch circuit so if the 8 AWG supply is NM cable it is a little short on ampacity.
 
PolkaV said:
Well sure, but I don't think anyone suggested that he do that. The 240V elements are a separate part which he'll have to order.

46 amps on 8/2 NM-B (if that's correct) would be another problem.
Click to expand...
Can choose to order correct elements or get a buck boost transformer.

You would assume elements would cost less, but maybe not.

either way too much for 8 AWG @ 60C ampacity. If it would happen to be a 75C ampacity then it is fine on 50 amp breaker.

If they intend to use this only occasionally likely can get away with 60C conductor, but still make sure is on 40 amp breaker. I'd bet it seldom if ever trips unless you are using it in more of a commercial manner, like running a small bakery out of your home.
 
kwired said:
unless you are using it in more of a commercial manner, like running a small bakery out of your home.
Click to expand...
Good point, OP mentioned its in the garage so that might not be considered part of the dwelling unit for 220.55, OP will need to make judgement call as to if its 'commercial' use.
 
kwired said:
Per note 5 in T220.55 single oven like this has branch circuit load the same as appliance rating so you can't apply demand factor to the branch circuit so if the 8 AWG supply is NM cable it is a little short on ampacity.
Click to expand...
Assuming the 46A figure is correct for the oven, the above problem is easily solved by installing a 4800W counter-mounted cooking unit in the same room on the same branch circuit. Then the note says you may treat the combination as one equivalent range with nameplate the sum of the nameplate ratings. 46A * 240V + 4800W = 15.8 kW, and a 16 kW range is 1.2*8 = 9.6 kW per Note 1. Which is 40A at 240V.

: - )

Cheers, Wayne
 
If its got a upper and lower element, you might be able to sub divide the oven into more than one circuit, like a electric on-demand water heater.
But if the panel is in the garage and the oven in the garage might be just as easy to run a 50A circuit.
 
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