For the past several weeks a leading headline in local and national news has been flooding. Flash floods in Nashville, Tennessee, northeast Nebraska, Arkansas, and most recently in France and China have reminded us of the dangers associated with rapidly rising waters.

Earlier this week I was glued to CNN as they showed Live coverage of a flood in Oklahoma City. In one instance, a driver seemed to weigh the risk of crossing through some rapidly moving water before deciding to take a chance. Even though the SUV had better than average ground clearance, its tires were soon covered and moments later the truck was swept off the road and disappeared into the newly formed stream. It made me wonder…what would happen if a hybrid electric vehicle, or possibly worse, an all-electric car became submerged in deep water? Would there be a shock risk for the passengers?

When hybrid cars first made their way to the U.S. about ten years ago, I remember that many people were concerned with the risks associated with their high voltage electrical systems. Some of this concern was fear of the unknown but it seemed reasonable that getting a really big battery wet could have negative consequences (here was an article on electrocution risks from 2004).

In doing some digging to better understand the risk potential, I came upon a How Stuff Works post that stated ”there isn’t a single case on record of a rescuer being shocked while extricating someone from a crashed electric or hybrid vehicle”, whether submerged in water or dry. The writer added that electric and hybrid cars have extensive safety systems to automatically turn off the power from battery packs when a collision or short circuit is detected.

In doing more research I discovered that the high voltage cables and hybrid batteries (often 400 volts or more) are more than powerful enough to be lethal. Wires are therefore enclosed in insulated and protective casing while the battery pack is sealed in a metal shell, isolated from electric current. The shell is treated to avoid corrosion and rust, and even if water breached it, nickel-metal hydride battery packs use maintenance free, sealed cells. Nothing can get in or out (supposedly).

Even so, the National Fire Protection Association (nfpa.org) will offer a program to train emergency personnel on avoiding shock from advanced electric-drive vehicles. From a recent press release on the subject - “The Obama Administration has established a goal of one million electric vehicles in the U.S. by 2015. The NFPA initiative, funded by a $4.4 million grant from the U.S. Department of Energy, will include a series of electric vehicle emergency response safety programs available to emergency first responders. The training programs will provide emergency first responders with information they need to most effectively deal with emergency situations involving these alternative-fuel vehicles“.

Complicating the issue of shock risk is the number of different technologies. Today’s popular hybrids have two power sources: an energy conversion unit such as an internal-combustion engine, and batteries. (The nickel metal hydride batteries found in the popular Toyota Prius and Honda Civic Hybrid are recharged through regenerative braking and by their gasoline-powered engines.) Plug-in hybrids have the same two power sources, except that the batteries can be charged from an electrical outlet. The electric motor of an EV is powered by batteries that can be recharged by plugging them into household receptacles. And fuel-cell vehicles, which also have electric motors, produce their electricity primarily with hydrogen. The upcoming release of the Chevrolet Volt and Nissan Leaf will likely stir up more conversation about this issue, so expect further updates.