Since December 20, 2010, regulations in the US have required 2-pole, 4-pole and 6-pole asynchronous AC motors with nominal power ratings between 0.75 and 150 kW in continuous duty type in line operation to satisfy the specifications of the Premium NEMA energy efficiency class (which corresponds to IE3). However, numerous exceptions to this requirement were defined such that motors of the Standard Efficiency class (IE1) and High Efficiency class (IE2) could continue to be sold.

As of June 1, 2016, the following combinations of power range and number of poles (in S1 continuous duty) are to be subject to American energy efficiency regulations:

As of June 1, 2016, motors to which the American regulations apply and that do not satisfy the criteria of the legislation may no longer be introduced on the American market.
The moment at which a motor is considered to be placed on the market is the time of its production, not the time at which it passes through customs. This means that a motor delivered before June 1, 2016 to a customer in Europe may still pass through American customs even after June 1, 2016, because the date of its production can be proven to precede the date that the heightened energy efficiency regulation came into effect.

However, there are rumors in the US market that US Customs authorities might perhaps apply the new rules in a stricter way, meaning they could potentially block as of June 01, 2016 such motors from entering the US which do not match the new regulations even if the production date was before or June 01, 2016. This may lead to delays in the US Customs, which could cause problems for customers with time-critical deliveries.

Customers can minimize the potential risk in the US Customs if they already switch to motors that meet the new rules and do not wait until end of May 2016.