Hello folks,
I have a commercial toaster. Name plate rating:
208V Singlephase
27 Amps
Running amps 28.5 Amps

If i put a breaker rated at 30 Amps it will break because the toaster runs 11 hours a day. If I go 125% of the rating then the breaker goes to 35Amps. But the lead wires from the toaster are only 10AWG.

What i have on there now is SO cord with 30Amp twistlock receptacle and 30Amp twistlock plug.

What should i do to be within NEC?

Regards,
Edward

You can not protect a 30 amp outlet with more than 30 amps.

The manufacture has installed a 30 amp cord cap, I would run a 30 amp circuit to this and not even worry about it.

It may not draw 28 amps continuously, it may cycle on and off as the thermostat dictates.

I can only reccomend SO cord and a plug if the toaster is often moved around.
If that is the case, you will want to upgrade to 8/3 SO. You'll also want to use a 40 amp connector into a receptacle that is rated to disconnect under load- most of your NEMA-pattern receptacles are not. Look into such things that are marketed for motors.

It is more likely that the toaster doesn't move around very much. It would be more common that it would be wired to a disconnect switch using a metal-lined liquid-tight flex, containing #8 wires.

One exception: it is permitted to use whatever type of cord & plug that the unit came with when manufactured. I suggest looking at the makers' web site to see if there are any reccomendations.

John I have never hardwired these types of items in commercial kitchens.

Usually (hopefully) they are moved for cleaning not to mention the need for a disconnect.

The commercial toasters I have seen are factory fitted with 10 cord, these units have a moving metal belt that brings the toast under the elements.

This could be different in this case but if it comes with a 30 amp cord and you change it out in order to up the OCP I believe you have a UL violation.

If it was UL listed for 30 amp OCP a 35 or 40 amp OCP would be a problem.

iwire,

the unit does not come with cord.(according to the owner). Here is what happened:

The original cord was burnt due to loose connection. Then i come in and replace it with a 6/3 range cord to match the existing 50Amp wall plug. Then the unit goes out for cleaning and the cleaning/repair shop tells the owner that is the wrong dryer cord.(yes they said it was a dryer cord). So they replaced the cord with a SO 10/3 with a 30amp twistlock plug. So i had to replace the existing 50Amp wall receptacle with a 30Amp receptacle to match the cord end that was put on by the repair shop.

So i do not know who is right and can not find the manufacturer's website so i can download some instructions.

Manufacturer. HOLMAN COOKING EQUIPMENT model# MM14

Edward

The owner has three units for two restaurants the one that went out for cleaning was the one that i had a 6/3 range cord on.

Edward

Well that changes my outlook entirely.

What does UL say about it. Would it void UL listing I wouldn't touch the appliance. If its commercial does it have a max fuse size listed, is the SO factory. I would look at the nameplate and factory cord size. Maybe up the feeder size after calculating the length of run but still keep the 30a brk recept and factory cord. Why use 125% is it there an inductive load to?If it's got a 30a line cord and trips a 30a brk it is a sign that there’s something wrong like low volts or leakage to ground(which can kill) by not tripping a 40a brk near as fast as a 30a if at all which brings me back to the UL question. I always Check for ground potential (chassis to chassis) with all metal objects in reach of my kitchen installations

Edward, here is a link for Holman-
http://www.holmancooking.com/fs_default.asp

steve

I that case they would all get 30a line cords brk recps ect according to the nameplate VALUES if it were me I might even call the manufacurer.

Voltage at the load is 200Volts (with the unit on) with the unit off it is 205 Volts.
At the panel it is 205 Volts.

Steve,
I also found that website but is not an official HOLMAN website. I think i will try to find a phone # Monday.

Existing feeder size is #6 and the existing breaker was 50Amp.

Edward

Edward, Holman Cooking Equipment 800-225-3958

Steve,

Thank you I will try thyem tomorrow.

Edward;

Bob (Iwire) was on to something when He mentioned the duration of time the Toaster will be on / off.

Simply, this equates to the "LCL thingee" we all know and respect
The "# Amps × 1.25" adder for Long, Continuous Loads is of design interest for this situation.

If the Toaster is on - and drawing full load current of 28.5 Amperes @ 208 VAC for 179 minutes, then is turned off for a brief period of time, this is not an LCL - as it falls just one minute shy of the 180 minute mark.

If the Toaster _DOES_ run at full load amperage of 28.5 Amperes @ 208 VAC for 180 minutes _OR MORE_, then it is an LCL - requiring an additional 25% of circuit ampacity rating (even though the appliance does not draw that additional 25% load current).

It's not a bad design idea to use a 35 or 40 Amp 208 VAC 1Ø circuit, since the Toaster is so close to the 30 Amp point - and it's a Resistance load which may tend to draw a higher load current as the system voltage increases (and vise-versa, decreasing load current as the system voltage becomes lower).

The 30 Amp cord might be an issue in more ways than simply insufficent ampacity - duty, enviroment, heat tolerance, etc. should be considered as well.

Here are some simple calcs, compiled from the listed values of the equipment and system:

Mfg. listed FLA: 27 Amperes @ 208 VAC 1Ø
w/ LCL = 33.75 Amps (27 × 1.25).
35 Amp circuit minimum.

Running Amps: 28.5 Amperes (was this measured by you while the appliance was running?).
w/LCL = 35.625 Amps. Looks like 40 Amp circuit minimum.

Using the FLA values of 27 and 28.5 Amps @ 208 VAC, it appears the Toaster has a total Resistance of 7.5 Ohms (7.3 Ohms for 28.5 amps, 7.7 Ohms for 27 amps @ 208 VAC).

If the system voltage is right at the "Target Value" of 208 VAC, the FLA will equal 27.73 Amperes @ 208 VAC.

I saw that you measured an unloaded circuit voltage of 205 VAC and a loaded circuit voltage of 200 VAC.
With these values applied to a 7.5 Ohm element, the FLA values would be:

FLA at 205 VAC: 27.334 Amperes (5603.47 Watts),

FLA at 200 VAC: 26.667 Amperes (5333.4 Watts)

and just for fun, if the voltage rises to 215 VAC, the FLA through a 7.5 Ohm element would be:

FLA at 215 VAC: 28.667 Amperes (6163.40 Watts).

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Let us know what the LCL standings are, and the measured values of Amperes @ X Volts.

Scott35

(Running Amps: 28.5 Amperes (was this measured by you while the appliance was running?).

Yes i measured this at the receptacle.

I assume there is a thermostat an it works.

Edward

Thank you guys for your input.

Specification and technical data sheet says:

"Minimum 50Amp plug and receptacle."

I will put that in and change the breaker to 35Amps.

Edward