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Subchapter 20. Tunnel Safety Orders
Article 15. Drilling

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§ 8450. Use of Jumbos in Tunneling Operations.

(a) Guardrails. Jumbo work platforms 7 feet 6 inches high and higher shall be equipped with standard guardrails in accordance with Sections 1620 and 1621(a) of the Construction Safety Orders.
(1) Ends or sides at which work is in process or where the open space between a platform edge and the tunnel wall is less than 16 inches.
(2) Where tunnel dimensions do not provide ample clearance lower guardrails may be used.
(b) Toeboards. Toeboards shall be provided around jumbo platforms in accordance with Section 1621(b) of the Construction Safety Orders to prevent tools or other equipment from falling off.
(c) Housekeeping. No tools, material, equipment, or other unattached objects shall remain on any platform while jumbo is being moved if any part of such object protrudes beyond width of jumbo.
(d) Access. Suitable access ladders or stairways with railings shall be provided on all jumbos. Platforms, ladder rungs, and stair treads on jumbos shall be made of nonslip grating or similar material to prevent falls caused by slick surfaces.
(e) Falling Rock. Overhead protection against falling rock and other objects shall be provided at all jumbo working areas by means of crown bars, solid platforms or other equivalent protection.
(f) Storage Racks. Where drill steel is kept on jumbo platforms, suitable receptacles such as boxes, racks, grooves or equivalent shall be provided for temporary storage.
(g) Handling Steel. When drill steel is hoisted, double slings and tag line or an equivalent method shall be used.
(h) Collaring Holes. Before starting to collar holes, a flashing light or visual warning shall be given to employees working below.
(i) Electrical. Where electric detonators are used, all electrical circuits to the jumbo shall be disconnected and the live ends removed to a minimum distance of 100 feet from the jumbo before explosives are brought up to the heading or bench.
(j) Only employees assisting the operator shall be allowed to ride on jumbos, unless the jumbo meets the requirements of Section 8493(a)(1) of the General Industry Safety Orders.
(k) Jumbos shall be chocked to prevent movement while employees are working on them.
Note: Authority cited: Sections 142.3 and 7997, Labor Code. Reference: Sections 142.3 and 7997, Labor Code.
1. Amendment of section and new Note filed 3-5-96; operative 4-4-96 (Register 96, No. 10).

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