Okay, let's break down the code requirements and practical considerations for your situation.

Understanding the Code (NEC) Limitations

The core issue here is the relationship between your 20A receptacles, the cord-and-plug connection to the motors, and the overcurrent protection device (OCPD, like a breaker or fuse). 20A Receptacles and Cord-and-Plug Connected Equipment

NEC 210.21(B)(1) states that where equipment is fastened in place, a receptacle shall have an ampere rating not less than the overcurrent device (OCPD) from which it is fed. However, 210.21(B)(2) indicates that a single receptacle connected to a branch circuit shall have an ampere rating not less than that of the branch circuit. In essence, if you're plugging these motors in, your receptacle limits you to a 20A circuit.

Motor Overcurrent Protection

NEC Article 430 covers motors and their protection. It allows for some oversizing of the OCPD to accommodate motor starting current. The key phrase is "instantaneous trip" or "inverse time" breakers.

The Conflict

The rub is that Article 430's allowance for oversizing the OCPD is intended to protect the motor and its wiring, not necessarily cord-and-plug connected equipment with receptacles.

The Problem with Oversizing with Receptacles

If you upsize the OCPD above 20A to handle the motor inrush, you violate the 20A receptacle limit. You might not damage the receptacle immediately, but in a fault condition, the receptacle could be subjected to currents beyond its rating, potentially leading to: Overheating. Melting/Arcing. Fire Hazard. Damage to the CordSolutions and Considerations

Here's how to approach this safely and in compliance with the NEC:1. Stay at 20A Breakers

This is the safest and easiest option. If you're constantly tripping breakers, consider the following:

Staggered Starting

If possible, don't start all 48 motors simultaneously. Stagger their start times to reduce the peak inrush current on each circuit.

Soft Starters

Implement soft starters. These devices gradually ramp up the voltage to the motors, significantly reducing the inrush current. This is the best technical solution.

High Inrush Breakers

Some manufacturers offer 20A breakers specifically designed for high inrush loads. These breakers have a time-delay characteristic that allows them to tolerate short-duration inrush currents without tripping, but still provide overcurrent protection. Research if a 20A breaker can handle the 5.1A start.

Load Distribution

Carefully balance the number of motors per circuit to minimize the inrush current. Could you reduce the number of motors on each circuit so the inrush is less likely to trip the breaker?2.

Hardwired Connections (Most Likely Required)

If you absolutely must upsize the OCPD beyond 20A to deal with the inrush current, then the motors must be hardwired (permanently connected). This eliminates the 20A receptacle limitation. This also means the equipment is fasted in place. Calculate the conductor size based on NEC Article 430 (motor circuit conductors). You'll need to consider the motor's nameplate current (2.6A) and the allowable ampacity of the conductors. Select an OCPD based on NEC Article 430 (motor overcurrent protection). This is where you can use the allowance for oversizing to accommodate inrush, but always check to be sure the wiring is protected. Terminate the conductors in a suitable junction box or directly to the motor's wiring compartment.3.

Reduce the number of motors

It may be worth discussing this as an option. Can you operate on a lower number of motors?

Important Considerations Before Proceeding Consult a Qualified Electrical Engineer or Licensed Electrician

This is a complex issue, and the NEC can be interpreted in different ways. A professional can assess your specific situation, perform load calculations, and ensure your installation meets all applicable codes and safety standards.

Local Codes

Local jurisdictions may have amendments to the NEC or additional requirements. Be sure to comply with all local regulations.

Motor Nameplate Data

Verify the motor's nameplate information, including voltage, current, and any specific instructions regarding overcurrent protection.*

Duty Cycle

How often and for how long do the motors operate? This can affect the conductor sizing and breaker selection.

In summary: The safest and most code-compliant approach with your existing 20A receptacles is to stay with 20A breakers. If you're consistently tripping breakers, investigate soft starters, high-inrush breakers, staggering the start times, or hardwiring the motors (if you need to upsize the OCPD). Always consult a qualified professional before making any changes to your electrical system. Flag for review