Keeping equipment warm, but not letting it burn

Poor electrical connections around block heaters are a leading cause of fires on farms

Poor electrical connections can melt or damage plugs, extension cords or the block heaters themselves.
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Faulty equipment stored or parked in barns or sheds remains a leading cause of farm fires. And the use of portable heaters, extension cords and block heaters in tractors significantly increases the risk.

Even properly functioning block heaters can cause a fire if they are plugged into a cord with a poor connection. Poor connections can include poor receptacles, plug ends and wiring, old or worn cords and the use of light duty or damaged extension cords, says Jim Zyta, vice-president, loss prevention at Heartland Farm Mutual. He’s also a member of the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) Reducing the Risk of Barn Fires Advisory Panel on fire prevention.

“It’s often assumed that a standard circuit breaker would just trip if there is a short in an extension cord, block heater cord or the block heater itself,” says Zyta. “But that’s not likely to happen.”

Why it matters: Mechanical failures or malfunctioning block heaters, electrical failures or damaged extension cords and electrical failures at the extension cord connection and block heater plug are the leading causes of fires caused by faulty equipment.

“I’ve inspected all types of barns and farm buildings over the years, and prevention is the best defence against the risk of fire,” he says, sharing his block heater safety and fire prevention advice.

Plugs are one of the areas where melting can occur. photo: Heartland Farm Mutual

Block heater dos and don’ts to reduce the risk of fire on your farm:


  • Closely examine the condition of the block heater plug and lead connection. Check for cracked or exposed wiring.
  • Make sure all motorized equipment is parked in a safe area away from combustible materials, especially underneath the machine.
  • Install battery cut-off switches to de-energize equipment when not in use. This reduces the chances of an electrical fire.
  • Consider replacing standard electrical breakers on key circuits, with an “arc fault breaker” or “arc fault receptacle”, which will trip when dangerous electrical arcing is detected from a damaged extension cord, plug or loose connection.
  • Install 15/20 amp arc fault device on 15/20 amp circuits to protect the electrical extension cords and block heaters.
  • Regularly inspect your extension cords and scrap those that are light duty or damaged. Most off-the-shelf extension cords are 16 gauge and should not be used on a farm.
  • New 14 gauge and 12 gauge with heavier insulation are now more available at local retailers.
  • Regularly inspect and replace all damaged extension cords.
  • Inspect barn receptacles for evidence of corrosion or deterioration.
  • Consult a licensed electrician on any electrical changes.


  • Avoid the use of power bars with extension cords to power multiple devices.
  • Never use old, damaged, light gauge, or multiple extension cords — they can be an ignition source.
  • Never use an extension cord longer than required. A coiled extension cord plugged in and powering a block heater cannot disperse heat, which can create extreme temperatures and become an ignition source.
  • Never use an extension cord buried under debris.
  • Never plug in a block heater in an area where combustible materials like dust, liquids or straw, are near or underneath the tractor.
  • Never plug in a block heater in an area where there is a high risk of methane gas build up, like an under floor manure pit.

For more farm fire prevention information, visit the Farm & Food Care website.

This article was produced as part of the Farm & Food Care Ontario: Livestock Emergency Preparedness Project and the Reducing the Risk of Barn Fires Advisory Panel (2016), which is a group of concerned Ontario farm commodity groups, fire prevention officers, electrical safety professionals and government of Ontario staff.

This project was funded in part through the Canadian Agricultural Partnership, a federal-provincial-territorial initiative. The Agricultural Adaptation Council assists in the delivery of the partnership in Ontario.

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