A combine that went up in flames within two hours of starting work, despite a driver described as meticulous about blowing the machine down, prompted one of the most practical machinery conversations of the harvest on The Farming Forum. Over five weeks, contributors traded hard-won experience on what actually starts combine fires, what prevents them, and why so few machines carry the suppression systems that insurers will discount premiums for. For dealers, insurers and suppliers the signal is clear: demand for fire protection exists, but the route to market is not working.
By TFF News | 10 September 2026 | Machinery
The conversation ran from 10 July to 17 August 2026 and drew 110 visible contributions, 6,745 views and 176 reactions, an average of 1.6 reactions per contribution. These figures describe one conversation among the farmers who chose to take part. They are not a representative survey of the sector.
Bearings first, dust and DPFs close behind
Failed bearings were the most cited ignition source among the 14 contributions on mechanical failure. The most agreed-with contribution described two fires: “In both cases they were down to bearings failing and dripping hot molten metal onto straw.” Another farm lost a machine entirely to a suspected internal bearing failure: “by the time anyone noticed something was amiss, the straw coming out the back was on fire. And that was that.”
On newer machines, emissions kit came up repeatedly among the eight contributions on exhaust dust. One contributor relayed what a suppression supplier told him at Cereals: “chaff on the DPF during a regen is one of the most a common causes of fire on newer machines”. This season’s conditions sharpen that risk: “W Barley dust is very fine this year and just accumulated on the exhaust manifold in a dead spot drawn across the engine by the radiator fan.” Sticking brake calipers and rodent-damaged wiring were also blamed.
The static question nobody fully settled
Static electricity was the single biggest theme, carrying 29 contributions. An Australian contributor with decades of dryland harvesting described it vividly: “At night, I have seen static sparks all over plastic / fiberglass body panels & small clumps of smouldering dust on vertical panels, when harvesting chickpeas.” The remedy discussed at length was dragging an earthing chain, standard practice in Australia. One UK contributor had adopted it after two fires on his own machines: “It sounds silly, but it works.”
Others were unconvinced: “why is it you can have dust sticking to glass on a cultivation tractor when it has enough metal buried in the ground to stall it?” Even the chain’s advocates accepted its limits on current machines: “I don’t think chains are as effective with plastic / fibreglass panels on modern machines”. The wider design point drew agreement across 14 contributions: plastic panels and plastic fuel tanks make modern combines both more static-prone and quicker to become a total loss. As one contributor put it, “A small fire can soon turn into a complete write off whereas old machines made of metal didn’t burn out so easily.”
The compressor rule
On prevention, the conversation was unusually unanimous. The most direct version came from Australia: “Unless you are blowing it down daily with an industrial / road type air compressor, then you aren’t cleaning it properly & you WILL get fires”. The logic was spelled out simply: “Also if you do it at least every day there simply isn’t the quantity of dust etc built up on the machine.” For the trade, a serious road-type compressor is being talked about as essential harvest kit.
Suppression systems: a gap between insurer and dealer
The commercial heart of the conversation was fire suppression. The most reacted-to contribution asked the question directly: “I’ve never understood why all combines aren’t fitted with race car-style plumbed-in fire suppression systems.” A contributor familiar with the suppression market answered with the industry position: “They can be installed on combines, but neither manufacturers or dealers currently offer them, if customers ask, then they can be sourced.” The same contributor stated that “NFU Mutual do discount combine premiums for machines that have an accredited system installed, currently 15%.”
Those figures check out against published sources. NFU Mutual offers a 15% premium discount for approved suppression systems meeting SPCR199, AS 5062-2016 or FM 5970 accreditation, and reported that more than 90% of its combine fire claims in 2022 and 2023 arrived in July and August, per Farmers Guide. Supplier literature cites a study of around 9,000 combine fires finding 77% start in the engine area, per Fireward, matching the figure cited above. Farmers Weekly put entry-level system costs at around £1,600, or 1 to 2% of a machine’s purchase price, per its 2024 report.
Yet uptake is clearly patchy. One contributor was “surprised that insurance companies don’t insist on stricter operating procedures and fire suppressant systems as part of the conditions”. Another passed on his engineer’s scepticism: “The guy that looks after mine isn’t keen on them because if they are deployed it make a hell of a mess.” The supplier-side contributor’s diagnosis of the stalled market was blunt: “the machines remain unprotected and the losses and claims continue to happen.” These are individual opinions, but they describe a distribution failure the trade could fix.
Water beats the extinguisher
Among 11 contributions on fighting a fire once it starts, experienced voices repeatedly warned that a powder extinguisher can make a smouldering dust pile worse: “When blasted into the pile of chaff and dust it caused a dust cloud which ignited violently.” The favoured kit was plain water in quantity: “I won’t turn the key unless there’s at least a 5 gallon barrel of water on the combine”; another has fitted a 130 litre tank and electric pump. The cheapest prevention of all was vigilance: “If you the operator or the trailer drivers smell burning however small check it out and look till you find it 15 minuets could save a few days looking for a replacement combine”.
A tinder-dry backdrop
Running underneath it all, in 19 contributions, was the season itself: a second consecutive bone-dry harvest, comparisons with 1976, and grain coming off the field at moisture levels contributors had never seen. The 75 year old who started the conversation, in his final season driving a combine, reflected: “I don’t think any farmer has harvested grain at such low moisture contents before!!!” If drier harvests are becoming normal, the fire risk conversation stops being seasonal.
The question left hanging
Nobody disputed that combine fires are a growing commercial exposure: machines worth £250,000 to £500,000, plastic-bodied, harvesting ever-drier crops. What remains unresolved is who moves first. Manufacturers and dealers do not offer accredited suppression systems on new machines, insurers discount but do not insist, and many customers do not know the discount exists. Whoever closes that loop, factory-fit suppression, a dealer-fit programme, or agents actively selling the 15% discount, will find an audience already convinced of the risk.
Read the source conversation and analysis
Read the full conversation on The Farming Forum here.
Download the full conversation analysis as a PDF slide deck.
This conversation had been viewed 6,745 times on The Farming Forum when counted on
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