Breaking Cornwall Devon

Following a surge in the number of barn fires Devon and Somerset Fire and Rescue Service is urging farmers to monitor temperatures in their haystacks

There have been ten barn fires since the start of July, many of them caused by spontaneous combustion. With recent wet weather making the cutting and storing of hay difficult, the fire service is concerned there is a risk of further barn fires.

The cause 

Due to the recent showery weather, hay may have been collected or stored when wet. Hay bales or stacks with high moisture levels (more than 22 percent) can have chemical reactions that build heat. If the temperature of a haystack rises above 55 °C a chemical reaction begins to produce flammable gas that can ignite if the temperature gets high enough.

Wayne Rawlins, Area Manager at Devon and Somerset Fire and Rescue Service said:

“We want local farmers to know that it’s important to monitor temperatures in their haystacks, as barn fires can be devastating, and difficult to put out. We know how precious hay stores are to farmers and we want to avoid any fires of this nature if we can.”

Advice for farmers 

  • Remove hay from fields as soon as possible after harvesting. Ensure it is dry before storing.
  • Store hay and straw away from other buildings – especially those containing fuels or chemicals, and separate from livestock.
  • Store hay and straw in stacks at least 10 metres apart and ensure there is sufficient space between the top of the stack and electrical roof lighting.
  • Hay fires are most likely within six weeks of baling.
  • Check hay regularly, including monitoring the temperature. You can insert a probe thermometer into the haystack to monitor the temperature.
  • If stored hay starts to smell of caramel, or there is a distinct musty smell, it is likely that your hay is heating. 
  • Watch out for haystacks reaching 65 C – this is the beginning of the danger zone. After this point, check the temperature daily.