Company Information

"Suitable for Motor Disconnect" HVAC/R

Adherence to product safety standards and concern for operator safety is paramount at Eaton.

Evidence exists that there are some manufacturers with improperly labeled and/or inadequately rated products, which have misguided customers, and thereby jeopardized operator safety.

Eaton "Suitable for motor disconnect" 600V switches have been manufactured in Canada since 2001 and are CSA certified to C22.2 #No.4.

With many manufacturers to choose from, awareness and education is needed to ensure the right choices are made when applying motor controllers for specific motor disconnect applications.

To identify if a motor controller or a disconnect labeled "suitable for motor disconnect" may cause a serious problem, it is suggested that checks for the following be made:

1. Labeling on the device:
1. Should never say "Manual Motor Controller" only
2. Look for Suitable for Motor Disconnect beside CSA or cUL designation
3. Upstream Fuse Type @ 600V *
4. Upstream Maximum size fuse @ 600V *
5. Short circuit rating @ 600V * (should not be less than10kA)
6. Horsepower rating
7. Acceptable wire type and size
8. Termination torque

* Fusing requirements cause a common misconception in the field. Although these motor disconnects are non-fused devices, to attain the short circuit rating and to prevent welded contacts, installation of the specified fuse type and rating noted on the label of the disconnect, is required upstream. The majority of manufacturers have approved their non-fused motor disconnects for 600V application to be used in conjunction with J fuses upstream. This may require additional circuit protective device modification/installation upstream!

As well as offering "suitable for motor disconnects" from 30 to 80 Ampere, Eaton has an extensive line of 30 to 1200Ampere knife blade safety switches available. Although physically larger in size and less economical than the motor disconnect switches, knife blade switches provide more fuse options and higher short circuit capacity.

Either switch option requires co-ordination between HVAC/R mechanical and electrical installers.

Debbie A Holland
Product Manager Switching Devices Canada
debbieaholland@eaton.com