Welcome to the forum! This is a great question.Here's my take on it, breaking down the issues and considerations

Understanding the Situation
Prefab Kitchen & Temporary Nature

The fact that it's a prefab kitchen doesn't automatically exempt it from standard load calculation rules. Even though it's temporary (5 years is a long time!), it's still an electrical load that needs to be calculated accurately.

Manufacturer's Connection Requirements

This is crucial. The manufacturer is telling you the minimum service you must provide for their equipment to function as designed. They've likely considered the full potential load of the kitchen when everything is operating at once.

Lack of Appliance Details

This is the tricky part. You don't know the specifics of the individual appliances.

Applying the NEC (Specifically Article 220) 220.3(A) General. Branch-circuit, feeder, and service calculations shall be made as specified in this article or by other methods specifically permitted for particular loads or conditions in other articles of this Code. This is a must when dealing with electrical load. 220.5(A) Voltages. Unless other voltages are specified, for purposes of calculating feeder and service loads, nominal voltages as listed in 220.5(A) shall be used. 220.10 General. Branch-circuit, feeder, and service loads shall be calculated as shown in Parts III, IV, and V of this article. 220.12 Show Windows and Track Lighting. Show window and track lighting loads shall be calculated in accordance with (A) and (B). 220.14(I) Other Outlets. Other outlets not covered in 220.14(A) through (H), except as provided in 220.15, for which loads are not determined by 220.3, shall be calculated based on 180 volt-amperes per outlet. 220.18 Dwelling Unit Receptacle Outlets. In other than dwelling units, receptacle outlets shall be calculated at not less than 180 volt-amperes for each single or multiple receptacle on one strap. A single receptacle supplying one appliance or utilization equipment shall be calculated based on the nameplate rating of the appliance or utilization equipment. 220.56 Kitchen Equipment. Commercial, institutional, and other kitchen equipment shall be calculated in accordance with Table 220.56 and shall be permitted to be calculated as follows



(1) Where it is known that all equipment will not be operated simultaneously, the load shall be calculated at 100 percent of the nameplate rating(s) of the two largest kitchen equipment. (2) Feeder capacity for kitchen equipment, other than dwelling unit(s), shall be permitted to be calculated in accordance with Table 220.56.

My Recommendation & RationaleGiven the information you have, here's my approach:1.

Start with the Manufacturer's Connection Requirements



Assume this is the minimum required capacity. This is the key piece of information you have. The manufacturer is responsible for ensuring their kitchen unit functions correctly, and they've stated the required service sizes.2.

Calculate the Load Based on Those Connections



460V 3-Phase Loads

Two 400A services. Calculate the kVA (or VA) for each: `kVA = (Volts Amps √3) / 1000` `kVA = (460 400 1.732) / 1000 = 318.5 kVA per service` `Total 460V kVA = 318.5 kVA 2 = 637 kVA`

208V 3-Phase Loads

Kitchen: 200A service. `kVA = (208 200 1.732) / 1000 = 72 kVA` Freezer: 100A service. `kVA = (208 100 1.732) / 1000 = 36 kVA` Cooler: 100A service. `kVA = (208 100 1.732) / 1000 = 36 kVA`

120V 1-Phase Load

Restroom/Changing Room: 100A service. `kVA = (120 100) / 1000 = 12 kVA`3.

Sum the kVA (or VA) Loads

Add up all the individual kVA values to get the total kVA demand for the kitchen. `Total kVA = 637 + 72 + 36 + 36 + 12 = 793 kVA`4.

Demand Factors (Table 220.56)

This is where it gets interesting.

If you have absolutely no information on the actual appliance mix and usage patterns, using Table 220.56 is risky because it assumes you have the nameplate ratings of all the equipment. Table 220.56 requires you to have the total connected load of kitchen equipment, which you don't.

However, since the manufacturer has provided these connections, it is likely that they already taken demand factors into account. Applying demand factors on top of that would be over calculating the load in most cases.

My recommendation is to skip applying Table 220.56 demand factors unless you can get a detailed list of all the appliances in the kitchen and their nameplate ratings.5.

Present Your Calculations & Assumptions

Clearly document your assumptions (that you're using the manufacturer's provided service sizes as the base load) and show your calculations. This is important for getting approval and for future reference.

Important Considerations & Next Steps

Contact the Manufacturer

Your best course of action is to contact the kitchen manufacturer. Explain that you need to perform load calculations for the electrical service. Ask them specifically: "Are the connection sizes you've provided based on the total connected load of the equipment, or have you already applied demand factors?" "Can you provide a list of all the appliances included in the kitchen, along with their nameplate ratings (voltage, amperage, wattage)?"

Local AHJ (Authority Having Jurisdiction)

It's always a good idea to consult with your local electrical inspector or AHJ. Explain the situation and your proposed approach. They may have specific requirements or interpretations.

Future Load Growth

Consider adding a margin for future load growth, especially if the kitchen is likely to have new appliances added over the 5-year period.

In Summary



Start with the manufacturer's minimum connection requirements. Calculate the total kVA (or VA) load based on those connection sizes.

Be very cautious about applying Table 220.56 demand factors unless you have detailed appliance information. Consult with the manufacturer and your local AHJ. Document everything!Let me know if you have any more questions. Good luck with your project! Flag for review