By Harry Ohde and Robert Hattier
All is quiet at the Dale neighborhood fire department. The firefighters are inspecting and cleaning the trucks, checking apparatus. The alarm sounds. A voice booms over the speaker system, “Structure fire, 1234 North Lane.” Drop everything. Run to the garage. Step into the bunker pants and the boots near the truck. Pull up suspenders and slide into a coat. Grab the helmet. Start the truck. The lights flash, sirens blare and the truck moves out of the garage minutes after the alarm.
The drive will be short. The truck arrives at the structure and fire personnel jump out. An officer assumes command, begins the scene size up and develops a fire suppression plan, using a 360-degree view of the structure. That officer will determine the conditions, the actions, the needs. Information calmly goes out on the dispatch. “Single story residence with fire on the roof.” “We need water supply and back-up line.” You also might hear, “Dangling wires from solar panels on roof. Will identify inverter location.”
In most fires, a quick and aggressive attack at the base of the fire will also handle issues of rescue, exposures, and confinement at the same time. The size-up time is shortened if the firefighting team can communicate with residents or facility personnel to provide information on the structure and to help identify the components of an array and battery storage.
Today, firefighters and other first responders must be trained to address a solar system in a fire emergency and understand general solar system fire safety. The following information, based on our training for firefighters, is in compliance with National Fire Protection Association (NFPA) 1001, Standard for Fire Fighter Professional Qualifications, and NFPA 1403, Standard on Live Fire Training Evolutions.
To be clear, fires are rarely caused by solar systems. However, when responding to a fire in a building with solar photovoltaic panels and storage, it is crucial for firefighters to know the possible hazards, such as inhalation exposure; electrical shocks and burns; falls from roof operations; roof collapse; and batteries.
In this article, we will share best practices in fire safety and photovoltaics. This includes how to handle any fire emergency at a structure with solar photovoltaic panels and battery storage; basic electrical and photovoltaic safety precautions; and how to handle an emergency with an electric vehicle.
The responsibilities of emergency operations are to a) stabilize the incident and provide for life safety; b) conserve the property and the surrounding environment; c) Remove endangered occupants and treat the injured; d) assure the safety and welfare of the department personnel.
We’ve composed a solar and battery storage checklist to use upon arrival for a structure fire; this is easily incorporated in current NFPA measures.
1. Identify required roof operations. Look for dangling wires on the roof or a smoldering component. Consider the weight of the photovoltaic array on an already weakening roof structure. Because of that additional weight, firefighters may not be able to address the fire from the roof. Also, roof vents, solar thermal panels, and photovoltaic arrays pose a trip hazard for firefighters conducting roof operations. Review the best hose routes around the array. Never cut into photovoltaic modules!
To perform vertical ventilation, select a spot at the highest point of the roof and as close to the fire as possible. If that is not possible, consider cross ventilation. Should a PV array become engulfed in a roof fire, use water in a fog pattern.
Be aware that biting and stinging insects could inhabit the module frame and junction boxes.
2. Identify inhalation hazards. During a fire or an explosion, the frame of a photovoltaic system can quickly degrade, exposing hazardous chemicals to direct flame and become dissipated in the smoke plume. This can cause inhalation hazards to the firefighters and surrounding people, animals, and the environment.
First and foremost, the firefighter must wear self-contained breathing apparatus (SCBA). Secondly, review whether the size of the emergency and involvement of the array require the need to protect populations downwind.
Why is this necessary? The chemicals released that could cause harm by inhalation or exposure are:
· Cadmium telluride, a known carcinogen which should not be inhaled
· Gallium arsenide which is highly toxic and carcinogenic
· Phosphorous – Phosphorous fumes are highly toxic. NIOSH recommends a maximum exposure limit of 5 mg/m3. A lethal dose of phosphorous is 50 milligrams.
Boron is also released, but poses not health risks to humans, animals, or the environment.
RELATED: Solar Power 101 and the Fire Service | Responding to Solar Fire Incidents | UL Releases Report on Firefighter Safety and Photovoltaic Systems | Drill of the Week: Lockout/Tagout Procedures
3. Identify photovoltaic wiring. Direct current photovoltaic conductors or wiring is run outside the building in metallic conduits. In doing this, keep in mind that there is no difference between AC and DC color coding! The photovoltaic wiring will be in a separate conduit from other systems in the home. The National Electric Code (NEC) dictates that each system–cable trays, cable, the outlet box, and junction box–are contained in their own raceways.
When working in proximity to electrical circuits, use insulated hand tools. Use an AC/DC meter to check for electricity flowing between two contacts.
Wiring exposed to the weather should be listed and labeled for outdoor use.
There are specific NEC requirements for ground fault protection for photovoltaic systems and components. There should be visible labels that warn if a ground fault is indicated as the normally ground conductors may be energized and ungrounded. In one-and-two-family dwellings, all “live” parts over 150 to the NEC maximum of 600 volts in circuits of the source and output of a photovoltaic system will be accessible to qualified persons only. Commercial and industrial buildings are permitted a maximum voltage of 1,000 volts DC. For a photovoltaic module, the maximum system voltage is calculated and corrected for the lowest-expected ambient temperature. The grounding connection point should be located as close as possible to the photovoltaic source to better protect the system from voltage surges because of lightning. Exposed non-current-carrying metal parts are grounded regardless of voltage.
So here’s why this information is so important to firefighters–or anyone else.
Electric Hazards. It turns out we humans will always have a varying resistance to electricity. It depends on the amount of current flowing through the body–no surprise there. Our resistance also depends on the current’s path and length of time in the body as well as body size and shape, area of contact, moisture on contacts, type of clothing and skin, and if you’re wearing any metal jewelry.
So let’s say you are connected to live electricity–by accident, of course. Take account of those variables as you consider the different physiological effects produced by the electricity in your body. At a lower amount of current (1 mA) you would notice a tingling sensation; at 5 mA an involuntary muscle reaction; at 6 to 30 mA comes muscle “tetanization” or a painful shock. Lastly, at .5 to 1.50 Amps, one stops breathing and the heart stops at 1 to 4.3 Amps.
Electric burns. Electricity in your body can also cause burns or tissue damage as the body is unable to dissipate the heat from the current. There are three types of burns: electrical, arc, and thermal. A firefighter should NEVER pull the electric meter as a means of shutting down power to a building.
Use Class C extinguishing agents, CO2, or dry chemical if a photovoltaic system shorts or starts a fire.
4. Lock-out/Tag-out Procedures. The lock-out/tag-out procedures are to safeguard firefighting personnel in a variety of emergency or non-emergency situations, such as equipment becoming unexpectedly energized during the start-up of machinery and equipment or the release of hazardous energy. The fire department must work with the facility personnel or residents to turn off and disconnect any equipment from its energy source before working around it. Here are the lock-out steps for a structure with a photovoltaic system and what to watch for.
a) Look for all electrical disconnects for the system and ISOLATE the system or execute a rapid shutdown. Disconnect all components and conductors in a solar system. The Uniform Fire Code specifies that the disconnecting means is accessible to the fire department. The NEC specifies that disconnects should be permanently marked as a photovoltaic disconnect and can be located at the meter, main electric panel, the inverter, the controller, and the battery bank. As stated earlier, firefighters must look for warning labels on electrical disconnects. In photo A., the inverter is flanked by two disconnects. The one on the right disconnects the array (DC) and the one on the left disconnects the inverter from the main electrical panel (AC).
A label will be show the disconnecting means for the photovoltaic power source — the operating current (lpmax), operating voltage (Vpmax), short-circuit current (Isc), open circuit voltage (Voc), maximum system voltage, and the UL listing and label.
b) It is very important for firefighters to be aware that an array will always generate electricity when the sun shines. There is no turning it off. Cut or damaged wires from a nighttime operation can become energized in the day time. Always assume the system is energized! Spotlights during a nighttime operations are not bright enough for the PV system to generate electricity. However, lightning IS bright enough to create a electrical surge.
c) What should firefighters keep in mind when it comes to fires in daylight in structures with a solar system? You cannot block all the sunlight. Full stop. You may try with foam or salvage cover but you cannot block it. First, the foam will slide off the array. Secondly, any salvage cover significantly reduces sunlight to the array but electricity can still be generated through the cover.
5. Photovoltaic Batteries. As a rule, batteries do not burn or they burn with great difficulty. However, firefighters must be aware of the potential of explosive and toxic gases released by batteries and prevent any open flames or sparks. Spilled electrolyte can react and produce toxic fumes and release flammable and explosive gases when it comes into contact with other metals. Once the firefighter has located the battery storage area, here are the precautions they must take for fire emergencies.
· Wear full protective clothing, i.e. The Protective Ensemble for Structural Fire Fighting and SCBA on positive pressure.
· Extinguish lead-acid battery fires with CO2, foam or dry chemical extinguishers.
· Do not use water!
· Never cut into batteries under any circumstances!
· If the battery is punctured by a conductive object, assume that the object has electrical potential.
Storage batteries in a photovoltaic system should be installed in accordance with the NEC Article 480. Storage batteries for dwellings will have cells connected to operate at less than 60 volts nominal. Lead-acid storage batteries for dwellings shall have no more than 24 (twenty-four) 2-volt cells connected in series (48 volts nominal).
6. Electric or Hybrid Vehicle Fires. As with any fire emergency, firefighters must position their apparatus and equipment to provide the best protection during the operation. They must take the same precautions with the vehicle batteries as described above for the photovoltaic batteries.
In general, firefighters and other first responders must be familiar with the NEC and International Electric Code for photovoltaic systems and components such as ground fault protection, the maximum system voltage, array setbacks, and to identify the labels for the disconnecting mean.
Contact us for more information on photovoltaic firefighter training. Also, click on the following links for online resources – http://osfm.fire.ca.gov/training/photovoltaics for training from the Office of the State Fire Marshal in California and www.iaff.org/pvsafetytraining for IAFF and IREC PV training.
Harry Ohde is the Renewable Energy Coordinator for IBEW (Local 134)/NECA (Chicago) Technical Institute. You can reach him at hohde@local134.org
Robert Hattier is the Renewable Energy Instructor for the IBEW (Local 134)/NECA (Chicago) Technical Institute. He can be reached at rhattier@ejatt.com
