{"id":594,"date":"2026-10-29T16:23:43","date_gmt":"2026-10-29T08:23:43","guid":{"rendered":"http:\/\/www.elitesfemmes.com\/blog\/?p=594"},"modified":"2026-10-29T16:23:43","modified_gmt":"2026-10-29T08:23:43","slug":"what-are-the-common-failures-of-explosion-proof-motors-and-how-to-troubleshoot-them-4401-fe6f07","status":"publish","type":"post","link":"http:\/\/www.elitesfemmes.com\/blog\/2026\/10\/29\/what-are-the-common-failures-of-explosion-proof-motors-and-how-to-troubleshoot-them-4401-fe6f07\/","title":{"rendered":"What are the common failures of explosion proof motors and how to troubleshoot them?"},"content":{"rendered":"

As an explosion proof motor supplier, I\u2019ve spent thousands of hours on the shop floor, walking side by side with plant maintenance teams, troubleshooting motors in petrochemical plants, grain elevators, and pharmaceutical facilities where a single motor fault isn\u2019t just a production hiccup\u2014it\u2019s a safety risk. Over the years, I\u2019ve seen the same failures pop up again and again, often because of small oversights that turn into costly downtime or, worse, a safety hazard. Today I want to break down the most common issues we face, how to spot them early, and the steps we use to fix them when they do strike. Explosion Proof Motor<\/a><\/p>\n

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First, let\u2019s get on the same page about what makes an explosion proof motor different from a standard industrial motor. These aren\u2019t built just to run; they\u2019re engineered to contain any internal spark or overheat so it can\u2019t ignite flammable gases, dust, or fibers in the surrounding environment. That extra layer of design means they\u2019re also more sensitive to things like improper installation, corrosive environments, and missed maintenance than your average motor. I\u2019ve watched a well-built explosion proof motor turn into a problem machine because someone skipped a simple gasket check or used the wrong lube. That\u2019s the lesson right there: prevention starts with understanding how these motors are meant to work.<\/p>\n

The first and most frequent failure we deal with is winding insulation breakdown. This is the silent killer of explosion proof motors. Winding insulation is what separates the electrical current inside the motor from the metal frame, and when it fails, you get a short circuit\u2014inside a hazardous area, that\u2019s a major risk. Where does this come from? A lot of the time, it\u2019s thermal overload. If a motor is running 24\/7 beyond its rated load, or if the ventilation vents are clogged with dust (super common in grain elevators), the insulation can break down over time. Another culprit is moisture or corrosive vapors seeping into the motor. Even a small amount of moisture can erode insulation, especially if the motor sits unused for long periods or isn\u2019t properly sealed after maintenance. I once worked with a chemical plant that had three identical explosion proof motors fail in a month\u2014turns out their new cleaning process was releasing a mild acid vapor that was creeping through the frame\u2019s terminal box seals, eating away at the winding insulation.<\/p>\n

Troubleshooting insulation breakdown starts with a simple resistance test, something we teach every technician on our service team. Use a megohmmeter to test the insulation resistance between the windings and the frame; for a properly functioning explosion proof motor, that number should be at least 1 megohm per kilovolt of motor voltage, and never below 1 megohm total. If it\u2019s lower, start by checking for external moisture. If the motor was recently opened or exposed to rain, leave it running at no load for a few hours to let it dry out\u2014just make sure the area around it is safe, no flammable materials nearby. If that doesn\u2019t work, check the seals: the terminal box gasket, drain plugs, and any conduit seals. Even a tiny tear in a gasket can let in moisture or vapors. For more serious cases, you\u2019ll need to clean the windings with a specialized, non-corrosive solvent and re-varnish them, but that\u2019s a job best left to our team because it requires re-sealing the motor\u2019s explosion proof enclosure properly.<\/p>\n

Next up, bearing failure. This is the most common mechanical failure across all industrial motors, but it hits explosion proof motors a little differently. Explosion proof motors rely on precise bearing alignment to keep the shaft rotating smoothly, and if bearings wear out, not only does the motor stop working, the increased friction can lead to overheating\u2014another ignition risk. The causes here are varied: over-greasing or under-greasing is a big one. I\u2019ve seen maintenance teams over-grease a motor to \u201cbe safe,\u201d and that excess grease builds up inside the bearing housing, traps heat, and wears out the bearing in weeks. Under-greasing, though, leads to metal-on-metal contact, which causes rough noise and premature wear. Another issue is misalignment between the motor and the driven equipment (pumps, conveyors, etc.). When the shafts aren\u2019t perfectly lined up, the bearings take extra strain, and over time, that leads to pitting or cracking. For explosion proof motors, bad alignment can also damage the end bells, which are part of the enclosure that contains any sparks. I once had a refinery plant call us out because their explosion proof pump motor had seized; when we pulled it apart, the bearing was fine, but the end bell was cracked from years of misalignment, which meant the motor was no longer compliant with its explosion proof rating. That\u2019s a huge cost\u2014not just a new bearing, but a re-certification for the motor.<\/p>\n

Troubleshooting bearing issues starts with listening. A properly running motor is quiet; if you hear a grinding, squealing, or rumbling noise, that\u2019s almost always a bearing problem. You can also check the motor\u2019s temperature: if the frame is hotter than normal (especially near the shaft ends), that\u2019s a sign of excess friction. To confirm, shut the motor down (lockout\/tagout first, always), feel the shaft for any play\u2014if it wiggles back and forth, the bearings are worn. The fix here: first, check your grease schedule. We recommend using the motor\u2019s rated grease (we stock compatible grease for all our motors) and only greasing according to the schedule in the manual\u2014usually every 3 to 6 months for continuous operation, and only one or two shots of grease at a time. For misalignment, schedule a precision alignment check with a laser tool (we offer this as a service) to make sure the motor and driven equipment are perfectly lined up. If the bearings are already worn, replace them with explosion proof-rated bearings\u2014standard bearings can cause sparks if they fail, which is a hazard.<\/p>\n

Third, improper enclosure sealing and breach. This is a failure unique to explosion proof motors, and it\u2019s one that\u2019s often caught too late. The whole point of an explosion proof motor\u2019s enclosure is that if a spark or internal explosion happens, the enclosure\u2019s walls and gaps are designed to cool the gases enough that they can\u2019t ignite the surrounding atmosphere. If that seal is broken, or if gaps are too wide, that entire safety feature is gone. How do these breaches happen? Poor installation is the top cause\u2014installers skipping gasket checks, over-tightening or under-tightening terminal box bolts, or using the wrong size conduit seal around power cables. I\u2019ve seen a grain elevator plant where a worker cut the conduit seal too short, so the gap between the cable and the seal was an eighth of an inch too big. When the motor produced a small arc during startup, that arc escaped through the gap and ignited grain dust, causing a small fire (no injuries, but $20k in damage). Another common cause is wear and tear from vibration\u2014over time, end bell bolts loosen, gaskets crack from temperature changes, or drain plugs corrode and pull out of place.<\/p>\n

Troubleshooting enclosure breaches requires a visual inspection, but not just a quick look. Start at the terminal box: check the gasket for tears or compression damage (if a gasket is too flat, it can\u2019t create a proper seal), and make sure all bolts are tightened to the motor\u2019s specified torque (we provide a torque wrench for installation, and remind teams not to use regular wrenches which can over-tighten and crack the frame). Next, check conduit seals: for every power cable going into the motor, the conduit must have a explosion proof seal within 18 inches of the motor. Measure the gap between the cable and the seal material\u2014it should be less than 10% of the cable diameter, per NEC standards. For wear and tear, do a quarterly vibration check: if vibration is higher than the motor\u2019s rated limit (usually around 0.1 inches per second for most models), that can loosen bolts and break seals. If you suspect a breach, stop the motor immediately, and have a certified inspector check the enclosure\u2019s gap lengths (the flame path) \u2014 that\u2019s the space where any internal gases are cooled, and if it\u2019s too wide, the motor is no longer explosion proof.<\/p>\n

Fourth, overheating and thermal overload. I touched on this earlier with insulation breakdown, but it\u2019s a standalone failure that\u2019s often misdiagnosed. Explosion proof motors are rated for a specific ambient temperature range\u2014run them in an environment hotter than that, or overload them, and they\u2019ll overheat, which can damage winding insulation and even cause the motor\u2019s enclosure to warp, breaking the seal. A lot of plant operators don\u2019t realize that a motor rated for -20\u00b0F to 104\u00b0F can\u2019t run 24\/7 in a 120\u00b0F chemical plant. That\u2019s a slow burn; the insulation breaks down over months, not days, so it\u2019s easy to miss until the motor fails. Another cause is blocked ventilation: explosion proof motors use external fins on the frame to dissipate heat, and if those fins are covered in dust or debris (super common in sawmills, grain elevators, and mining), heat builds up inside, even if the ambient temperature is low. I had a sawmill that had 5 of our 10 HP explosion proof motors fail in a year; when we walked the floor, we saw the fins were completely covered in sawdust, and the maintenance team hadn\u2019t cleaned them in 2 years. Each time a motor heated up, the sawdust trapped it, leading to insulation failure.<\/p>\n

Troubleshooting overheating starts with checking the ambient temperature of the area around the motor. Use a thermocouple to measure the temperature within 3 feet of the motor\u2014if it\u2019s above the motor\u2019s rated maximum, you\u2019ll need a higher-temperature motor or better ventilation. Next, inspect the ventilation fins; if they\u2019re dirty, shut the motor down and clean them with a low-pressure air hose (no high pressure, which can bend the fins) every 3 to 6 months, depending on the environment. For overload issues, check the motor\u2019s nameplate rating and compare it to the load it\u2019s running. If it\u2019s running at 125% or more of its rated load, you\u2019ll need a higher horsepower motor\u2014running a standard motor above its rating is bad, but running an explosion proof motor above its rating is a safety risk because of overheating.<\/p>\n

Now, how do you prevent these failures from happening in the first place? From my years as a supplier, I can tell you that 80% of explosion proof motor failures are preventable with basic maintenance. First, stick to the maintenance schedule we provide with every motor\u2014we tailor each schedule to the environment, from weekly visual checks in dusty areas to quarterly electrical tests. Second, train your maintenance team on explosion proof-specific rules: never modify a motor (like cutting the frame or changing the enclosure), never skip gasket checks, and only use explosion proof-rated replacement parts. A lot of operators will grab a standard bearing or a standard gasket to save money, but that\u2019s a false economy\u2014those parts can cause sparks or break the enclosure\u2019s seal. Third, schedule annual inspections by a certified technician\u2014we offer on-site inspections for all our customers, where we test insulation resistance, check enclosure seals, and verify alignment, before a small issue becomes a big problem.<\/p>\n

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At the end of the day, explosion proof motors are a critical line of defense in hazardous environments. As a supplier, our job isn\u2019t just to sell you a motor\u2014it\u2019s to make sure it runs safely for years, with minimal downtime. If you\u2019re dealing with frequent motor failures, or you need to upgrade your current motors to meet new safety standards, we\u2019re here to help. We offer custom motor solutions tailored to your specific environment, 24\/7 service support, and training for your maintenance team.<\/p>\n

Synchronous Motor<\/a> References<\/p>\n

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  1. National Electrical Code (NEC) Article 500-515: Hazardous (Classified) Locations<\/li>\n
  2. ANSI\/ISA-12.12.01: Explosion-Proof and Dust-Ignition-Proof Electrical Equipment for Hazardous (Classified) Locations<\/li>\n
  3. IEEE Std 112: Standard Test Procedure for Polyphase Induction Motors and Generators<\/li>\n
  4. NEMA MG 1: Motors and Generators, Part 12 (Explosion-Proof Motors and Generators)<\/li>\n<\/ol>\n
    \n

    Xi\u2019an Simo Motor Co., Ltd.<\/a>
    Xi\u2019an Simo Motor Co., Ltd. is well-known as one of the leading explosion proof motor manufacturers and suppliers in China. Please feel free to buy high-grade explosion proof motor in stock here and get quotation from our factory. All customized products are with high quality and low price.
    Address: No. 159 Mingguang Road Economic and Technological Development Zone, Xi’an, Shaanxi Province, China
    E-mail: mkt-sales@simo.com.cn
    WebSite:     https:\/\/www.simomotor.com.cn\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

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