As we discussed earlier, PV systems consist of multiple mechanical and electrical components, and so safety practices and procedures are critical to reducing or eliminating installation errors, electrical hazards, or injury (or death) on job sites. We saw that NEC has guides for safety requirements for designing and installing PV systems such as voltage and current limits, OCPD and ground-fault devices, and disconnects.
Aside from the aforementioned regulations, this section describes safety practices and procedures that must be used to install PV systems. PV is an electrical system, and workers can get injured. Non-electrical hazards are usually caused by human error, due to carelessness or failure to adhere to safety requirements. Installers should be alerted to different non-electric hazards they may encounter on the installation site. Cuts, bumps, falls, and sprains can cause as much hazard and lost time as electrical shock and burn hazards.
The Occupancy Safety and Health Administration (OSHA) creates a set of regulations that requires employers to provide a safe place for employees while reducing hazards. OSHA 29 CFR part 1926 applied to general construction practices includes several practices applicable to PV systems. OSHA 10 [1] is a recommended basic training for all workers.
In order for PV installers to reduce/eliminate their number of injuries, an awareness of potential hazards and a program where safety rules are frequently reviewed are required. This can be accomplished based on safety training series' offered to workers. Construction sites contain a number of risks that we will discuss in this section. Installers should know that these risks are continuously changing based on new materials and technologies, so regular updates on these topics are recommended.
There was a time when training was not available for workers to comply with safety regulations. One of the best, effective ways to convey the importance of complying with regulations is by illustrating real examples of incidents. For that reason, OSHA has put together a series of training videos to make training appealing to workers. Some of these videos on the following pages are directly related to PV installations, and some are general examples of construction work related hazards. We encourage our solar professionals to watch all videos to get an idea about the importance of OSHA training and safety regulations in general.
Common electrical accidents are classified as:
These injuries can occur when electric current flows through the human body. The injury can become critical depending on the amount of current, the path through the body, and the duration. It is difficult to estimate when current will flow or the severity of the injury that might occur because the resistivity of human skin varies from just under a few ohms to several hundred thousand ohms depending primarily on skin condition and moisture. DC current generated by PV systems can cause continuous arc, and if it travels through a part of the body, it may cause serious burns. Power conditioning units are hazards, as they generate high AC voltage that can cause injuries as well.
This OSHA prevention video describes how to prevent deaths and injuries from employees' contact with overhead power lines while using ladders. Find more information on this topic on the OSHA website [2].
In the U.S., hundreds of construction workers die every year while on the job, with over 700 fatalities just in the year 2011. The third leading cause of these deaths is electrocution. Electrocutions cause one of every ten construction worker deaths, with nearly 70 deaths in 2011. But these deaths can be prevented. The video you are about to see shows how quickly contact with overhead power lines can result in the electrocution of a worker. The video will also show what employers must do so that the work can be done more safely. Employers have a responsibility to provide a safe workplace and protect workers against possible hazards. You’ll see that training workers, pre-job planning and taking the right precautions save lives. Please be advised. The scenes you are about to see deal with deaths at construction sites and might be disturbing for some people. All scenes are based on true stories.
Two workers were hired to caulk windows on a new three-story townhouse. There were overhead power lines located 20 feet from the house and about 25 feet above ground level. One worker was using a 40-foot metal extension ladder to reach and caulk the third story windows, while another worker was on the ground caulking windows. The ladder was extended to reach a vertical height of 31 feet above ground. The ladder’s base was set 8 feet from the side of the townhouse.
After the worker finished one window, he came down from the ladder. He tried to move by the ladder by himself, with the ladder still extended in the upright position. But the ladder was top heavy and too unstable and it fell backwards while the worker was still holding it. As it fell, the aluminum ladder contacted the overhead power line near the townhome. Because the worker was using a highly conductive metal ladder, it allowed the electrical current in the power lines to reach the worker. He died instantly.
Let’s look at the events leading up to this tragic incident, and see how it could have been prevented. Originally the worker climbed down the ladder and tried to move it by himself. Because the ladder was still in the upright position and extended, it was too hard to handle even though the worker was himself a safe distance from the power line. As a result, it fell over and hit the power line. Because the worker was holding the metal ladder when it hit the power line, it allowed current to pass through the worker’s body to the ground.
Now let’s take a look at the worker doing the same task safely: This time, before starting to work, the worker and his foreman inspect the area including checking for overhead power lines. After checking on the voltages with the utility company, the foreman and the worker discuss safe working distances from the power lines. The foreman reminds the worker of the need to keep himself and the ladder clear of the power lines at all times. As an added safety precaution a fiberglass ladder is selected for use in this area. While the fiberglass ladder is heavier, it has non-conductive side rails and two workers can safely handle it. As before, the worker climbs down the ladder to move to the second window, but this time he calls over to his co-worker to help move the ladder. The two workers first bring the extended section down, and then carry the ladder horizontally toward the second window to prevent the ladder from hitting the overhead power lines.
Now that you have seen how to perform this work safely, let’s go over some important points to prevent these types of electrocutions at work sites: All workers need to be trained about the hazards. Maintain clearance from overhead power lines. Working too close can expose the worker to an electric arc that could result in burns, a shock, or electrocution even if the worker does not contact the power line. In addition to maintaining clearance from overhead lines, use ladders with non-conductive side rails as an added safety precaution. Using ladders with non-conductive side rails is safer but not a guarantee of protection from an energized power line. In addition, ladders are not rated for electrical safety, so, it is important to always use safety precautions that maintain safe distances from overhead power lines.
Inspect ladders before and after each use. Only use ladders that are clean, dry and undamaged. For example, if a fiberglass ladder is not kept clean, dry, and in undamaged condition it can conduct electricity. Don’t carry or move extension ladders in the upright position. Get help moving ladders to keep control and prevent accidental contact with energized overhead power lines. If a ladder should accidentally hit an overhead power line do not touch it, quickly move away and call the electric utility company immediately. If appropriate clearance from an overhead power line cannot be met, contact the utility company to de-energize and ground the line or request the utility company install insulation over the lines to protect workers.
This example shows the importance of employers following OSHA standards to ensure that workers are provided with a safe workplace. These types of construction deaths are preventable. The protection measures shown here save workers’ lives. Use these protections on the job: it could be the difference between life and death. If you would like more information, contact OSHA at www.osha.gov or [3] 1-800-321-OSHA. That’s 1-800-321-6742.
This OSHA prevention video describes how to prevent deaths and injuries from contact with overhead power lines while using cranes. Find more information on this topic on the OSHA website [2].
In the U.S., hundreds of construction workers die every year while on the job, with over 700 fatalities just in the year 2011. The third leading cause of these deaths is electrocution. Electrocutions cause one of every ten construction worker deaths, with nearly 70 deaths in 2011. But these deaths can be prevented. The video you are about to see shows how quickly contact with overhead power lines can result in the electrocution of a worker. The video will also show what employers must do to ensure that the work can be done more safely. Employers have a responsibility to provide a safe workplace and protect workers against possible hazards. You'll see that training workers, pre-job planning and taking the right precautions save lives. Please be advised. The scenes you are about to see deal with deaths at construction sites and may be disturbing to some people. All scenes are based on actual events.
Two construction workers were replacing a section of pipe in a trench next to a road. They were using a crane to unload the pipe from a truck and place it on the ground close to the trench. While one worker operated the crane, another worker was on the ground to help direct the pipe toward the ground near the trench. The worker directing the pipe had one hand on the tagline, which was attached to the rigging used to lift the load. As the crane operator began to move the pipe, the crane's boom contacted an overhead power line. The electrical current traveled through the boom, down the load line, along the tagline, and reached the worker. He died instantly.
Let's look at the events leading up to this tragic incident, and see how it could have been prevented. The worksite did not have many of the required controls in place to protect workers from overhead power line hazards. For instance, before the work started, the employer had not set up the required clearance distance to keep the crane a safe distance from the overhead power line.
Let's take a look at the same work area, this time with proper precautions in place. All workers are trained, this includes the crane operator being certified and the rigger and spotter fully qualified. Because the line is "live" (or energized), the employer has taken steps to keep a safe distance from the power line: The foreman obtained the voltage of the overhead power line from the utility company. Based on the voltage, he determined the minimum required distance of the crane from the power line. A pre-job safety planning meeting was held. Flags are set up to show the boundary that must not be crossed. A non-conductive tag line is used to control the movement of the pipes. The truck is no longer directly below the power line. And a spotter is on site with a two-way radio to communicate with the operator.Higher voltage lines will require greater minimum safe distances and additional precautions than those shown here. Now, as the pipe is moved, the boom remains a safe distance from the power lines and the worker safely guides the pipe towards the ground near the trench.
This video shows one of several options employers can use to keep workers safe when operating cranes near power lines. Not all worksites are the same, and the precautions could be different than those shown here. Construction deaths from electrocutions are preventable. The precautions shown here save workers' lives. Follow safe crane operation requirements on the job: it could be the difference between life and death.
If you would like more information, contact OSHA at www.osha.gov or [3] 1-800-321-OSHA that's 1-800-321-6742.
According to the OSHA website [5], Lockout/Tagout (LOTO) refers to "specific practices and procedures to safeguard employees from the unexpected energization or startup of machinery and equipment, or the release of hazardous energy during service or maintenance activities." This can be done by:
The following video (1:57) offers more information on this subject.
An electrician was working on an open electrical panel on a ship. He needed to add a new cable and attach it to a breaker within the panel. The electrician identified the isolation breaker that fed the entire panel on the schematic drawing. The electrician de-energized the breaker and properly tagged out. As the electrician was fitting the new cable into the panel his left hand came into contact with the panel's main bust bars. Four hundred forty volts of current passed from the bus bars through his left hand, across his chest, and out his right hand that braced him against the panel electrocuting him. At some point the tagged out isolation breaker had been crossed wired with another breaker. The electrician did not know that the panel he was working on was never de-energized. (MUSIC)
Let's look at some of the contributing factors that led to this fatality.
Employees should verify the location of all energy isolation points. Employees must check or test electrical panels or electrically powered equipment to ensure they are in fact de-energized before working inside them or within the vicinity of exposed electrical circuits. Inform all contractors and subcontractors of the ship's systems and/or modifications to the systems prior to beginning work. (MUSIC)
Any system with batteries forms a potential hazard. Some areas of concern include:
A fall is considered the primary cause of death in the construction industry. OSHA fall protection regulations apply to PV systems since PV systems can be installed in locations where climbing a ladder, working on roof, or use scaffolds is required.
A training on fall protection should be offered to workers on how to use fall protection systems and devices to avoid injuries that include:
The following video discusses OSHA's fall protection policies for residential construction.
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The following videos cover various falls in construction.
There are two types of slopes that exist on roofs, and special attention should be taken:
Require emergency stop switches at the operator station or the motor
At heights greater than 10 feet, the fall protection requirement for workers on scaffolds is different from the general construction requirement at 6 feet or greater, as mentioned in section 29CFR1926.451(g)(1). See the following video for more.
OSHA requires a signal person when:
Each power tool has its own set of requirements for use, and some come with safeguards. For most PV systems, workers will use electric power tools, air-filled tools, hydraulic tools, and tools that require liquids such as gasoline. Good understanding of the hazards associated with the power source will reduce the number of potential incidents and injuries.
Personal protective equipment (PPE) protects worker dangers, such as falling items, unsecured materials, and loud noises, that can cause injury. Examples of PPE include:
PV systems are installed where the sun is brightest and no shade exists. Sunburn and dehydration due to extreme temperature may occur.
Installers should pay attention to any of inhabitant in the site where the PV system will be installed. Serious injuries may occur due to neglect. The site may be treated against these hazards before the installation starts.
Most PV systems contain metal items with sharp edges and can cause injury if you are not careful. Installers should wear gloves when handling metal, particularly if you are drilling or sawing.
Many PV systems are installed in remote areas in rough terrain with different altitudes. Walking to and around the site, particularly carrying materials or test equipment, can result in falls and/or sprains. Installers should follow correct dress codes from head to toe.
The following videos offer more on sprains and strains.
Metal left exposed in the sun can reach high temperatures that can cause serious thermal burns. In addition, most stand-alone PV systems contain acid batteries that can create acid burn hazards. Chemical burns will occur if the acid makes contact with an unprotected part of the body. Safety glasses and gloves are recommended for installers.