I have purchased a commercial grade convection oven for my home because I run a baking business from my kitchen. Here is the plate information:
230 Volts
53 Amps
Single Phase or 3-Phase wiring (planning on single phase of course)
All of my other major appliances are gas, but even still I don't have enough wattage left in my 100AMP panel box so I am upgrading it to a 200AMP service.
My question: I am planning on using a 60AMP breaker to carry this thing, and although I know 6 Gauge wire is used for this amperage, should I be using 6/2? or should I be using 6 Gauge THHN wire? The run is less than 75 feet.
#6 gauge romex is only good for 55-amps so you cannot connect to a 60-amp breaker. Also assuming you did use romex it would have to be a 6-3 with ground (4 wires).
Is the 53A for single phase or when it is wired to 3 phase.
Also you say this is for a bakeing business you have in your house, how long will this stove be running. Does it go all day or a couple hrs a day. The reason I ask if it is used all day you will have to consider it a contoinus load which means you will have to derate it by 80%. I am assumeing the NEC is the same when it comes to continous loads to what the CEC says.
This would take you to 53/.8=66A. So now your looking at #4(based on CEC may be different in the NEC) and a 70A breaker.
4-wire feed is not required on an appliance with a 240 volt only rating. Only if it is rated 120/240 volts would a neutral conductor be needed. It appears this is not the case in this instance.
As for the wire size and circuit breaker, the #6 is rated for 55 Amps. Since the nameplate requires 53 Amps, that is within tolerance. You are allowed to use the next-size standard breaker, which is 60 Amp.
Such an appliance would have to be direct-wired in most cases.
I am pretty sure I don't have the connections for a 4 wire feed. It is indeed a 240 volt rating only. I only have 2 lugs in the oven itself and of course a ground.
I see what you are saying about about the 53A nameplate rating... but this continuous load thing has me thinking of of kicking it up a notch just to be safe. I never bake anything at the full 500 degrees though, so I don't think I would ever touch that 53A. What are your thoughts?
Darren makes a good point! I typically size my wiring to 125% of the load for continuous loads which works out about the same (53 x 1.25 = 66.25-amps) = #4 wire)
It should work out to the exact same, that is the same as dividing by .8. I just rounded down when I put the number in.
Kbsparky- We are always taught to make anything in a commercial setting a continous load. I do agree that oven probably won't be pulling 53A but have always been taught to bump a commercial stove. In the OP case I would not consider it a contoinous load, so wire with whatever the NEC says is good.
This is true, but I don't keep the same bread in the oven for the 3 hours. It is a series of bread pans for about 45 minutes each. So the oven does not get turned off in between.
The Romex 6 Gauge wire is rated at 55amps... would it be foolish to upgrade the the 6 Gauge THHN wire rated at 75amps and still use the 60A breaker? Is the 75feet run a important consideration? The Romex 6 gauge is appealing so I don't have to run conduit, but I want to do it right, not cheap.
If the rating of the stove was 55a you could still use #6 wire rated at 55a
You might hit 53a for a brief time period if you had every burner on high & the oven at the same time
Load would drop off as burners/oven reached temp
Unlikely you would ever run at even close to 53a for any extended time period
That sounds good to me. My crawlspace only has about 18" clear so being under there running wire in conduit is something I would love to get out of. I think I am going to go with using 6/3 romex wire on a 60 amp breaker. I don't need the extra (red) wire, but i would rather have it in case I ever to put another unit that would require it.
Typically a commercial range or oven is not allowed in a residence, because it does not have the same safety features. Is your oven rated for a residence? I know they make a commercial grade that is. Your insurance may not pay if you get one tha is not, and you could be putting your family in unnecessary dangers.
Just a thought to consider.
Another thought: I am definitely going with the 6 gauge THHN wire because if I do have to up the amperage because the 60amp breaker can't handle it I want to have the option.
So 2- 6 Gauge THHN wires and 1-8 Gauge THHN ground wire. Can I run the THHN wire in SCH. 40 conduit with no issues?
I'd think an oven with a 'right-sized' heating element would be on all the time, 100% duty cycle, when the highest temp. is selected. Like a 'right-sized' furnace on the coldest day.
Have you considered clearance to cabinets or other appliances in the kitchen. Commercial appliances are not insulated the same way as residential appliances so the outside gets hot. They are designed to be placed against other commercial appliances that are not combustible. I believe that you will have both warranty and insurance problems with this appliance in you home.
The manufacturer won't honor the warranty in a residential install and you home insurance at least needs to know that you have this thing in your house. If you have a fire and that's when they find out you had a commercial oven...good luck.
Your heat management problems will be serious if you are baking for several hours in a day. Let's say it would take 60 min to preheat to 475 if you want crusty bread and then you're baking for another few hours your kitchen and house will be unbearable.
12 kw = 40,000 BTU/hr, about 1/4th the size of my gas furnace.
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