Subchapter 7. General Industry Safety Orders
Group 6. Power Transmission Equipment, Prime Movers, Machines and Machine Parts
Article 37. Purpose, Definitions and Standards

§3944. Guard Clearances.

(a) Where a guard or enclosure is within 2 inches of moving parts, openings through the guard shall be of such size as will preclude the passage of any object one-half inch in diameter.

(b) Where a guard or enclosure is within 4 inches of moving parts, openings through the guard shall be of such size as will preclude the passage of any object greater than one-half inch in diameter.

(c) Where a guard is located between 4 inches and 15 inches from moving parts, the maximum opening shall be of such size as will preclude the passage of any object greater than 2 inches in diameter. Where a slatted guard is used, the width of the opening shall be not greater than 1-inch.

(d) Standard railing guards shall be placed not less than 15 inches nor more than 20 inches from any moving parts provided; however, that where clearances from other moving parts are less than 15 inches, such parts shall be guarded as required elsewhere in these orders.

(e) The use of nylon mesh or materials of equivalent strength with holes not exceeding 1/2-inch to modify an existing substandard fan guard is acceptable, provided the combination of the two provides adequate protection and the mesh cannot be pushed into the danger zone during normal use.

Table G-1 GUARD MATERIALS
Material	A Clearance from moving part at all points (See Fig G-2) Inches	B Largest mesh or opening allowable (See Fig G-1) Inches	C Minimum gauge (US Standard) or thickness Gauge/Inches
Woven wire	Under 2	3/8	No 16
	2-4	½	No 16
	4-15	2	No 12
Expanded metal	Under 4	½	No 18
	4-15	2	No 13
Perforated metal	Under 4	½	No 20
	4-15	2	No 14
Sheet metal	Under 4		No 22
	4-15		No 22
Plastic	Under 4	½	*
	4-15	2	*
Plywood or equivalent	Under 4		5/16
Plywood or equivalent	4-15		5/16
Solid wood	Under 4		1
Solid wood	4-15		1
Wood or metal strip crossed	Under 4	3/8	Metal No 16   Wood 3/4
	4-15	2	Metal No 16   Wood 3/4
Wood or metal strip not crossed	Under 4	½	Metal No 16    Wood 3/4
	4-15	1	Metal No 16    Wood 3/4
Standard rail	Min 15
	Max 20
Other materials that meet the strength requirements of this table and provide equivalent protection may be used
* Tensile strength of 10,000 lb/in2

Table G-1

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   Note: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.

 HISTORY     1. Repealer of Table G-2 and Figure G-8, and renumbering of Table G-3 to Table
G-2, filed 11-18-76; effective thirtieth day thereafter (Register 76, No.
47). For prior history, see Register 76, No. 6.

2. Amendment of Section 3944 and repealer of Tables G-1 and G-2, Figures G-1,
G-2, G-3, G-4, G-5, G-6, G-7 and new Tables G-1 and G-2, Figures G-1, G-2, G-3,
G-4, G-5, G-6, G-7 filed 5-4-77 as an emergency; effective upon filing.
Certificate of Compliance as to Table G-1 included (Register 77, No. 19).

3. Editorial correction in Figure G-1 and Certificate of Compliance as to 5-4-
77 filing filed 8-31-77 (Register 77, No. 36).

4. Repealer of Table G-2 filed 12-19-78; effective thirtieth day thereafter 
(Register 79, No. 1).

5. Amendment of Section 3944 and Tables G-1, G-2 and Figure G-7 filed 10-9-85;
effective thirtieth day thereafter (Register 85, No. 44)

6. Editorial correction of Figure G-2 and deletion of duplicate Note and
History Notes (Register 95, No. 24).

7. Change without regulatory effect providing more legible illustrations for
Figures G-1 through G-7 filed 2-18-2009 pursuant to 
section 100, title 1,California Code of Regulations (Register 2009, No. 8).