Ladders in building operations are gradually being replaced by scaffolds, platforms, and trestles over the years. However, it is still extensively used by workers involved in maintenance and interior decoration jobs, including technicians engaged in water, electricity and gas works, etc. Ladders are commonly made of timber or metal, such as aluminum folding ladders.
Accidents involving the use of ladder occurred every now and then. In a typical fatal case, a worker was assigned by his employer to repair a ceiling light flushed into a metal grid of the false ceiling. He was standing on an aluminum ladder to reach for the lightbox. While he was inspecting the wiring above the false ceiling, he might have come into contact with the earthed metal casing of the lightbox. The possible live conductor might have come from the faulty earthed metal light box casing, or from some faulty electric wirings above the false ceiling. After careful examination, the aluminum ladder might have been energized by a faulty electric wire on the floor, near one of the footings of the ladder. The rubber footing of the ladder was missing.
It was suspected that this was the source of energy causing the accident. To complete the circuit, the current was passed onto the ladder, through the body of the worker and to the earthed metal casing of the ceiling light, leading to electrocution.
Data from the Health and Safety Executives in the United Kingdom on the fatalities in the construction sector between 1997 and 2001 showed that the most common cause of fatal accidents resulting from falls within this sector occurred as a result of a fall (52%). Of this, 23% fell from ladders, although the type of ladder involved was not specified. The occupational groups most affected were painters and decorators being the most common victims of fatal falls from a ladder.
Ladder Design
The US Department of Labor’s Occupational Safety and Health Administration (OSHA 3124 1997 (Revised)) recommended, among other things, the use of ladders where the desired rise from the horizontal is at an angle of 50° or more, or where a stairway is not practical; use a stair ladder for inclines between 50° and 75°; the use of a vertical ladder for angles greater than 75°; the use of stairs for rises between 20° and 50° and the use of ramps for inclines less than 20°.
Ladder Design Principles
The first step from the ground must be reachable by the shortest expected the user, and at least two handholds must be accessible to this person while he or she is still on the ground.
The steps or rungs must accept the user's shoe, with the shoe being placed for a firm step; i.e., the midpoint of the shoe, not just the toe, must rest solidly on the step. Each step or rung should be sufficiently wide so that the person can stop and rest both feet on it.
Plan the position of each succeeding step and its associated handhold so that the user's final entry into the vehicle will be compatible with sitting in the seat. Remember that when a person climbs a ladder, the hand, and leg that are making the next move are on opposite sides of the body. If handholds
and steps are not planned to conform to this natural "climb pattern," the person will more than likely end up with the wrong foot ready to enter the workstation; i.e., usually, a person cannot hold and step from the same side without swinging. Do not create a system that forces the user to step on a
hubcap, tire, or another irregular surface.
Provide sufficient clearances for a person exiting the workstation to turn around and face a vertical ladder to climb down.
The specific contour of handrails must follow the gripping, pulling, and support patterns associated with both entry and exit; entry and exit are generally quite different and sometimes require more than one handrail geometry.
Non-Vertical (Stair) Ladders
Nonvertical ladders should have flat horizontal threads (as opposed to round rungs) and two handrails. The most familiar example of this type is the ship's ladder, which usually rises at an angle of 68° from the horizontal (50° - 60° is a preferable range), with a clearance for only one person. Use separate up and down ladders for simultaneous two-way traffic. Two-way ladders should use a maximum tilt angle of 60°, preferably with a double handrail in the center:
Vertical Ladders
Use round rungs to provide both hand grips and foot supports for vertical ladders
(inclines between 75° and 90°), as shown below -.
Stairs
Stairs should rise from the horizontal at an angle of between 20° and 50°. The preferred angle is between 30° and 35°. This rise angle automatically determines the ratio of riser height to tread depth, but the minimum riser height should be 5 in.
Avoid long continuous flights of stairs. Where space permits, provide landings every 10 to 12 threads. In addition, enclosed stairs should have a handrail on at least one side. For open stairways and landings, provide a guardrail halfway between the handrails and treads. In addition, provide screen guards between the guardrail and floor for landings where the stairway is at right angles to the landing
General safety hints
▪ Ladders should not be used for supporting loads.
▪ Straight or extension ladders securely fixed at the top.
▪ For extended heights, such as lamp posts, consider the use of mobile scaffolds or powered platforms.
▪ Never use metal, aluminum or other conductive ladders near electrical installations or live exposed electrical equipment.
Maintenance
▪ Secure ladders near the top and/or at the bottom to prevent them from slipping.
▪ Place ladders at the proper angle (1:4 from base to vertical rise).
▪ Extend ladders above the landing by 1 m.
▪ Avoid using ladders near busy passageways or roads with busy car traffic, use other means or otherwise fence off the area.
▪ Keep ladders in good conditions and free of defects.
▪ Check all ladders before use for broken rungs or other defects periodically.
Additional hints:
Aluminum, or any metal ladder, should not be used near live cables or equipment
except in specialized work such as in high voltage substations where nonconductive ladders might present a greater hazard than conductive ladders. A proper safety system of work, coupled with a lockout system, should be in place.
The most commonly used access equipment for working at height is the portable ladder • The main types of portable ladder commonly used are,
1. Single ladder.
2. Extension ladder.
3. Stepladder.
Selecting a ladder:-
o Must select the correct type of ladder for the area in which it's going to be used.
o Portable metal ladders must not be used. Where there is a risk of contact with electricity, fiber class ladders should be used.
o Ladders should be positioned on a firm level surface at an angle of 75° (1:4).
Never position a ladder:-
o In front of outward opening doors.
o Against a window.
o On top of boxes, loose bricks to gain extra weight.
o The end of the ladder extends at least one meter.
o Past the landing platform.
o Secure the ladder at the top to prevent falling.
When using a ladder:
o Always use the ladder only one percent of a time.
o Use all the rungs don’t double step.
o Use both hands when climbing the ladder.
The general requirement of ladders:
o All ladders shall be of good conditions free from rust and deformations.
o Ladders used for electrical work shall be of non-conductive materials.
o Ladders shall be security and evenly supported. On both sides and shall not be footed on loose material.
o When ladders are used in the presence of the public a second man will be required at the bottom of the ladder.
o To ensure that no harm to the public is the person performing the job.
o Portable ladders shall inspect them before use and ladders with broken or missing rungs split side rails shall not be used.
o Heavy objects or hazardous material shall not be carried by workers on ladders.
The standard length for ladders:
1. Stepladder – 20 ft
2. Single ladder – 30 ft
3. Extension ladders
a) Two sections – 48 ft
b) More than two section – 66 ft
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