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Technical References

SURVIVING HOSTILE CONTROL SYSTEM ENVIRONMENTS

There is an IP-rated UL-recognized environmental sealing

boot expressly designed for selected control components

(e.g., switches, circuit breakers, potentiometers, panel

meters) that mates with and will provide a number of benefits

consistent with design considerations that comply with MIL-

DTL-5423 specifications. Originally designed for U.S. military

naval applications — rugged handling (with and without

gloves), corrosive atmospheres, lubricant contact, frequent

wash-downs — these sealing boots have repeatedly proven

their battle-tested worthiness. By supporting all the major

manufacturers of switches, potentiometers, and circuit break-

ers, the same protection and reliability are available for a

wide spectrum of commercial and industrial switches

through the APM HEXSEAL® and E-SEEL® sealing boot

system. The following reference data and cross reference

charts should be helpful in making your selection, however

please do not hesitate to contact our sales support depart-

ment for assistance.

Enclosure Ratings

To cost-effectively satisfy this application diversity, manu-

facturers of electrical/electronic equipment enclosures offer

a range of products which provide varying degrees of envi-

ronmental protection. In the interest of “standardizing” an

electrical enclosure’s performance, standards-making organ-

izations such as NEMA, UL, CSA, and IEC have established

various standards (Table 1).

Use of NEMA ratings does not require independent testing.

Compliance is left to the manufacturer. On the other hand, UL

conducts an independent evaluation of the submitted product.

Tests are performed either at UL’s laboratories or witnessed by

UL engineers at the manufacturer’s location. In addition, UL

requires follow-up inspections (which may include testing) to

assure adherence to prescribed materials and manufacturing

procedures.

These ratings provide a quantitative measure of an enclo-

sure’s ability to operate in the environment in which it will be

used. Each rating defines the degree of protection against

rain, snow, sleet, wind-blown dust, hosedown, corrosive

agents, and occasional submersion.

While the detailed wording of ratings from standard to stan-

dard varies, each is based on similar application descriptions

and performance expectations (Table 2). For example, an

enclosure meeting UL Standard 50, Type 6 ratings (and simi-

larly NEMA Standard No. 250, Type 6) is designed for indoor

and outdoor use. It provides the degree of protection against

hosedown, icing, dust, and the entry of water during temporary

submersion at the limited depth required for this rating.

Table 1.

Selected Electrical Enclosure Standards

• National Electrical Manufacturers

Association NEMA Standards Publication

No. 250, “Enclosures for Electrical

Equipment”

• National Electrical Manufacturers

Association NEMA Standards Publication

No. ICS6, “Enclosures for Industrial

Controls and Systems”

• Underwriters Laboratories Inc. UL 50,

“Standard for Safety, Enclosures

for Electrical Equipment”

• Underwriters Laboratories Inc. UL 508,

“Standard for Safety, Industrial

Control Equipment”

• Canadian Standards Association CSA

Standard C22.2 No. 94 “Industrial

Control Equipment for Use in Ordinary

(Non-Hazardous) Locations”

• International Electrotechnical Commission,

IEC 60529 (Ed. 2.1 b:2001) “Degree of

Protection Provided by Enclosures

(IP code)”

Table 2. NEMA Enclosure Types

Type

Intended Use and Description for Electrical Equipment

1 .........Indoor use primarily to provide a degree of protection against limited amounts of falling dirt.

2 .........Indoor use primarily to provide a degree of protection against limited amounts of falling

water and dirt.

3 .........Outdoor use primarily to provide a degree of protection against rain, sleet, windblown

dust and damage from external ice formation.

3R.......Outdoor use primarily to provide a degree of protection against rain, sleet, and damage

from external ice formation.

3S .......Outdoor use primarily to provide a degree of protection against rain, sleet, windblown

dust and to provide for operation of external mechanisms when ice laden.

4 .........Indoor or outdoor use primarily to provide a degree of protection against windblown dust

and rain, splashing water, hose-directed water and damage from external ice formation.

4X .......Indoor or outdoor use primarily to provide a degree of protection against corrosion,

windblown dust and rain, splashing water, hose-directed water and damage from external

ice formation.

5 .........Indoor use primarily to provide a degree of protection against settling airborne dust,

falling dirt, and dripping noncorrosive liquids.

6 .........Indoor or outdoor use primarily to provide a degree of protection against hose-directed

water, and the entry of water during occasional temporary submersion at a limited depth

and damage from external ice formation.

6P .......Indoor or outdoor use primarily to provide a degree of protection against hose-directed

water, the entry of water during prolonged submersion at a limited depth and damage

from external ice formation.

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12K .....Indoor use primarily to provide a degree of protection against circulating dust, falling dirt,

and dripping noncorrosive liquids.

13 .......Indoor use primarily to provide a degree of protection against dust, spraying of water, oil,

and noncorrosive coolant.