Selection Assistance for Safety Switches

The following basic safety switch selection information covers types of safety switches, typical switch configurations, fuse class compatibility, voltage and amp ratings, pole count, neutral requirements, enclosure specifications, wiring diagrams, and NEMA application criteria.

Steps to select a safety switch

Select product type:
- General duty safety switch
- Heavy duty safety switch
- Double throw safety switch
Select switch type.
Select fuse type: fused, non-fused, cartridge, class T or plug
Select maximum voltage: 240 Vac / 250 Vdc, 600 Vac / 600 Vdc
Select amperes:
- General/light duty – 30 A, 60 A, 100 A, 200 A, 400 A, 800 A
- Heavy duty – 30 A, 60 A, 100 A, 200 A, 225 A, 400 A, 600 A, 800 A, 1200 A
- Double throw – 30 A, 60 A, 100 A, 200 A, 600 A
Select number of poles:
- General/light duty – 1, 2 or 3
- Heavy duty – 2, 3, 4 or 6
- Double Throw– 2, 3, 4 or 6
Select if neutral is needed.
Select enclosure type:
- General/light duty – NEMA 1, NEMA 3R
- Heavy duty – NEMA 1, NEMA 12K, NEMA 3R, 5, 12, NEMA 4, 4X, 5 (stainless steel 304), NEMA 4, 4X, 5 (stainless steel 316)
- Double throw – NEMA 1, NEMA 12K, NEMA 3R, 5, 12, NEMA 4, 4X, 5 (stainless steel 304)
- Optional enclosure types for special heavy duty applications.

Also see the following for additional information for safety switches:

Online Product Selector: Safety Switches Product Selector

Product Catalogs:

Supplemental Digest Catalog Section 2: Safety Switches. 0100CT2402–SD-SEC-02
Square D Enclosed Safety Switches Catalog. 3100CT1602

Product Ranges:

Safety Switch Wiring Diagrams

Fused Switch	Fused Switch with Neutral	Non-Fused Switch

Safety Switch Enclosure Types

Enclosure units are third party certified to UL 50E by Underwriters Laboratories

NEMA Type 1 Enclosures
Designed for indoor use in general-purpose applications, NEMA Type 1 enclosures protect electrical equipment against accidental contact with energized components and limited amounts of falling dirt. They are commonly used in clean, dry environments such as commercial buildings, offices, and electrical rooms where protection from dust, moisture, or corrosive conditions is not required.

NEMA Type 3R Enclosures
Intended for indoor or outdoor use, NEMA Type 3R enclosures protect equipment from rain, sleet, and external ice formation while allowing ventilation where required. They are commonly used for service entrance equipment, disconnect switches, and outdoor distribution equipment where weather resistance is needed but protection against windblown dust or hose-directed water is not required.

NEMA Type 4X Enclosures
Suitable for indoor and outdoor applications, NEMA Type 4X enclosures protect against windblown dust, rain, splashing water, hose-directed water, and corrosion. Typically constructed from stainless steel or nonmetallic materials, they are widely used in food processing, wastewater treatment, marine, and chemical environments where washdown capability and corrosion resistance are essential.

NEMA Type 12 Enclosures
Designed for indoor industrial environments, NEMA Type 12 enclosures protect equipment from circulating dust, falling dirt, lint, fibers, and dripping or lightly splashing non-corrosive liquids. They are commonly used in manufacturing facilities, machine tools, and automation systems where contaminants could affect electrical components but weather protection is unnecessary.

note

Type 4X enclosures can be used for Type 4 or Type 5 Applications.
Type 12 enclosures can be used for Type 5 applications and Type 3R via removal of drip hole knock out or drain screw.
Type 3R (800 and 1200 A Heavy Duty) are shipped as Type 5 - must remove drain screw for Type 3R applications.

Safety Switch Class H, R, J, and L Fuse Provisions

Class R Fuse
Application

Plug Type Fuses: Fuses for standard circuits (not high-voltage appliance circuits) are called plug fuses and have screw-in bases. There are two different types of bases and screw-in fuses: the Edison base (found on Type T fuses) and the rejection base (found on Type S fuses).

Class H or K Fuse Provisions: Fusible Square D 30–600 A heavy duty safety switches accept Class H or K fuses as standard. With Class H or K fuses installed, the switch is UL Listed for use on systems with up to 10 kA available short circuit current.

Class R Fuse Provisions: Fusible Square D 30–600 A heavy duty safety switches will accept Class R fuses as standard. A field-installed rejection kit is available which, when installed, accepts only Class R fuses. With the installation of the rejection kit and Class R fuses, the switch is UL Listed for use on systems with up to 200 kA available short circuit current.

Class J Fuse Provisions: Provisions for installing Class J fuses are included in 30–400 A 600 Volt, and 100–400 A 240 Volt, fusible heavy duty safety switches. Conversion to Class J fuse spacing requires relocating the load side fuse base assembly from the standard Class H fuse location to an alternate position as marked in the enclosure. With Class J fuses installed, the switch is UL Listed for use on systems with up to 200 kA available short circuit current. Switches rated 600 A, 240 or 600 Volt require the addition of an adapter kit: H600J.

Class L Fuse Provisions: Fusible 800 and 1200 A safety switches use Class L bolt-in fuses and are rated for use on systems with up to 200 kA at 600 Vac maximum. 1200 A switches accept class L fuses from 601–1200 A, 800 A switches accept Class L fuses from 601–800 A.

Section 3: Safety Switches