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Technical Bulletin

Document No. 155-756

TB256

August 29, 2018

Enclosure Ratings and Their

Applications

Siemens Industry, Inc.

Abstract

There are a wide variety of enclosure styles available when supplying variable

frequency drives (VFDs). Understanding these styles and their associated uses is

critical when selecting the enclosure that will allow for a successful installation.

Selecting enclosures that do not meet the environmental needs of the installation can

cause poor product operation and premature product failure that is likely not covered by

product warranty.

IP Rating vs.

UL Type vs.

NEMA Type

Enclosures

• IP ratings for enclosures are increasingly being observed in North America with the

proliferation of worldwide standards and inter-continental product shipments.

IP ratings for enclosures are governed by European standard IEC 60529 and are

recognized internationally.

The IP rating of a product is made up of a two-number descriptor, as described in

the following table:

First number = Solid object protection

Second number = Liquid protection

0 = No protection

1 = Objects over 50 mm (2.0 in.)

1 = Vertical falling drops of water

2 = Objects over 12 mm (47 in.)

2 = Spray of up to 15 degrees vertical

3 = Objects over 2.5 mm (0.10 in.)

3 = Spray of up to 60 degrees vertical

4 = Objects over 1 mm (0.04 in.)

4 = Light spray all directions

5 = Dust protected with limited ingress

5 = Light jets of water all directions

6 = Totally protected from dust

6 = Jets of water all directions

7 = Water immersion to 1 meter

• UL Type enclosure ratings are written as application descriptions and expected

performance guidelines. The governing guidelines are UL 508 for Type 1 enclosures

and UL 50 for all other enclosures. UL requires that the enclosures be tested to

qualify for the listed Type rating and the specific test guideline as described. UL also

inspects enclosure manufactures and field sites to ensure adherence to the

prescribed guidelines.

A short summary of the UL Type description follows:

Summary of content (4 pages)

PAGE 1
Technical Bulletin Document No. 155-756 TB256 August 29, 2018 Enclosure Ratings and Their Applications Abstract There are a wide variety of enclosure styles available when supplying variable frequency drives (VFDs). Understanding these styles and their associated uses is critical when selecting the enclosure that will allow for a successful installation.
PAGE 2
Technical Bulletin Document Number 155-756 August 29, 2018 IP Rating vs. UL Type vs.
PAGE 3
Enclosure Ratings and Their Applications Technical Bulletin Document Number 155-756 August 29, 2018 IP Rating vs. UL Type vs. NEMA Type Enclosures (Continued) NEMA Type enclosure ratings are written as application descriptions and generally follow the same guidelines as UL Type. One significant difference between NEMA Type and UL Type ratings is that NEMA does not require third-party testing and leaves compliance completely up to the manufacture.
PAGE 4
Technical Bulletin Document Number 155-756 August 29, 2018 Applying the Appropriate Enclosure Rating to the Application (Continued) Enclosure Ratings and Their Applications UL Type 4 and 4X • Protected against water from all directions. • Wash-down areas. • 4X gives the added protection of being corrosive resistant. These enclosure types include stainless steel and fiberglass. • Typically used in industrial locations not associated with variable torque HVAC drive locations.