Electric oven connection

[thunder15j]

We are in the process of running a new circuit to an electric oven at a lab testing facility. The oven is nameplated at 5800 watts @208 volts (27.9 amps). My first thought is to add 25% for constant duty and make it a 40 amp circuit with a 40/2 circuit breake along with a 50 amp receptacle and plug.

On second thoughts is this overkill? Should one consider running a 30 amp circuit because of the fact that the oven will probably cycle on and off? The run is a short distance so running the 40 amp circuit is not the much more in cost.

[edward]

My first thought is just do 40Amps.

What does the instruction say? Does it say a maximum OCPD?

[thunder15j]

No listed minimum circuit amp. nor OCD. I am running 40 amp circuit.

[Dennis Alwon]

Ovens should not be considered continuous load. Is the oven rated only 208V and what is the voltage to the unit.

[Dennis Alwon]

Remember that oven will draw more amps if the source voltage is 240v

[thunder15j]

The nameplate on the oven is for 208 volts only. Usually I see a nameplate that is for 208/240 volts. My customer asked if we would connect it for a 240 volt supply but we refused, fearing the we would probably damage the unit by causing it to draw too many amps with the higher voltage push.

[thunder15j]

We will be supplying the unit with 208 volts. (single phase)

[broadgage]

Ovens should not be considered continuous load. Is the oven rated only 208V and what is the voltage to the unit.

Normally I would agree, no normal housewife would run a kitchen oven at maximum temperature for 3 hours, what food stuff requires cooking in a very hot oven for 3 hours ?

However in this case it is stated that the oven is to be installed in a lab.
This to me suggests 2 possibilities.
Firstly the lab MIGHT be engaged in approval or durability testing of kitchen ovens, and perhaps run them for days as a test.
Secondly, it MIGHT not be a domestic cooking oven at all, but some variety of lab equipment for heat treatmnent, endurance testing of heat resistant equipment or the like.

In either of these special cases it could well run for much more than 3 hours.

Or of course it might be a standard domestic oven used for food development, recipie testing or the like, in which case a non continous load is a reasonable assumption.

[thunder15j]

Normally I would agree, no normal housewife would run a kitchen oven at maximum temperature for 3 hours, what food stuff requires cooking in a very hot oven for 3 hours ?

However in this case it is stated that the oven is to be installed in a lab.
This to me suggests 2 possibilities.
Firstly the lab MIGHT be engaged in approval or durability testing of kitchen ovens, and perhaps run them for days as a test.
Secondly, it MIGHT not be a domestic cooking oven at all, but some variety of lab equipment for heat treatmnent, endurance testing of heat resistant equipment or the like.

In either of these special cases it could well run for much more than 3 hours.

Or of course it might be a standard domestic oven used for food development, recipie testing or the like, in which case a non continous load is a reasonable assumption.

You bring up a great point about this application. This is a commercial oven and since I do not know the on/off cycles ( which might change even if they were known) , I am considereing it as constant duty. All the more reason for the heavier circuit.

[infinity]

In order for an appliance to be a continuous load it must run continuously at it's maximum current for 3 hours or more. My guess is that this will never happen with an oven. What does T220.55 say about the demand factor?