{"product_id":"blue-sea-5232-bss-20a-mdl-glass-fuse-set-of-2","title":"Blue Sea 5232-BSS 20A MDL Glass Fuse, Set of 2","description":"\u003cp class=\"nvn-hero\"\u003eThis is Blue Sea Systems' 5232-BSS, a set of two 20 amp MDL glass tube fuses rated to 32 volts DC. MDL means slow-blow, so they ride through the startup surge of pumps and motors without nuisance blowing. They drop straight into Blue Sea ST Glass Fuse Blocks and any AGC or MDL holder. Keep a spare aboard.\u003c\/p\u003e\n\n\u003cdiv class=\"nvn-description\"\u003e\n\u003cp\u003eBlue Sea Systems makes this 5232-BSS set so you've always got the right fuse on hand when a circuit lets go. It's a two-pack of 20 amp MDL glass tube fuses, rated to 32 volts DC, built for the ST Glass Fuse Blocks and any AGC or MDL fuse holder on your boat. Simple part. But the right one matters more than people think.\u003c\/p\u003e\n\u003cp\u003eThe MDL designation is the important bit. MDL fuses are slow-blow, also called time-delay. That means they tolerate a brief current spike without opening the circuit, then still protect the wiring if the overload sticks around. Why does that matter? Motors and pumps pull a big slug of current the instant they start up, often several times their running draw. A fast-acting fuse sees that inrush and pops, leaving you with a dead pump and a head-scratch. A slow-blow rides through the startup surge and only blows on a real, sustained fault. That's exactly what Blue Sea recommends these for, pumps and other motor loads.\u003c\/p\u003e\n\u003cp\u003eThese are classic glass tube fuses in the 3AG size, the familiar quarter-inch by inch-and-a-quarter cartridge that drops straight into AGC and MDL holders. The glass body lets you eyeball a blown element, you can see the melted strip at a glance instead of pulling a meter out. Each one is rated at 20 amps and up to 32 volts DC, which covers both 12 volt and 24 volt systems on just about any boat.\u003c\/p\u003e\n\u003cp\u003eWhere do they live on the boat? Most often in a Blue Sea ST Glass Fuse Block, the kind that lets you label circuits, stash a spare, and pull a fuse without a tool. But any standard AGC or MDL holder takes them, including inline holders on a single run. If you've got a bilge pump, a washdown pump, a macerator, or a livewell pump wired through a glass fuse holder, a 20 amp MDL is a common value for those mid-draw motor circuits. Always size the fuse to protect the wire, not the device, and check the load's rated draw before you settle on an amperage.\u003c\/p\u003e\n\u003cp\u003eOne quick note on AGC versus MDL, since the two look identical and share the same holders. AGC fuses are fast-acting and MDL fuses are slow-blow, but they're the same physical 3AG glass cartridge, so they interchange mechanically. For a steady, non-motor load, a fast-acting fuse is fine. But for anything with a motor or a startup surge, the MDL time-delay behavior is what keeps you from nuisance blows. This 5232-BSS set is the MDL, slow-blow version.\u003c\/p\u003e\n\u003cp\u003eBlue Sea sells these as a set of two for a reason. One goes in the holder, one goes in the spare slot or your ditch kit. Fuses are the cheapest insurance on the boat, and the one time you need a 20 amp MDL at 5 PM on a Sunday is the one time the local shop is closed. Keep a couple aboard for every amperage you run.\u003c\/p\u003e\n\u003cp\u003eInstalling one is about as simple as it gets. Kill the circuit, pull the old fuse, drop the new one in, done. The only thing to get right is the amperage. If this 20 amp value keeps blowing, don't jump up to a bigger fuse to make the problem go away, that's how wiring gets cooked. A fuse that blows repeatedly is telling you the circuit is drawing more than it should, and the fix is finding out why. If you're not sure what value your pump wants, check the motor's rating plate or give us a call, we rig this stuff every day.\u003c\/p\u003e\n\u003cp\u003eBlue Sea Systems builds for the marine environment, and even something as basic as a fuse benefits from a quality part with consistent, repeatable blow characteristics. A cheap off-brand fuse that blows early or late defeats the whole point of circuit protection. For a boat's DC system, where a nuisance blow can mean no bilge pump when you need it, it's worth running fuses you can trust. Grab a set, label your block, and keep your electrical system honest.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul class=\"nvn-features\"\u003e\n  \u003cli\u003eMDL slow-blow (time-delay) design rides through motor and pump startup surge without nuisance blows\u003c\/li\u003e\n  \u003cli\u003e20 amp rating sized for mid-draw DC motor circuits like bilge, washdown, and livewell pumps\u003c\/li\u003e\n  \u003cli\u003eRated to 32 volts DC, works on both 12V and 24V marine systems\u003c\/li\u003e\n  \u003cli\u003eGlass tube 3AG cartridge with a visible element for at-a-glance fault checks\u003c\/li\u003e\n  \u003cli\u003eDrops into Blue Sea Systems ST Glass Fuse Blocks and any standard AGC or MDL fuse holder\u003c\/li\u003e\n  \u003cli\u003eSold as a set of two, one to install and one for the spare slot or ditch kit\u003c\/li\u003e\n  \u003cli\u003eBlue Sea Systems quality for consistent, repeatable blow characteristics\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cdiv class=\"nvn-trust\"\u003e\n  \u003ch2\u003eWhy Buy from NVN Marine\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eAuthorized Blue Sea Systems reseller, full manufacturer warranty\u003c\/li\u003e\n    \u003cli\u003eNMEA member and ABYC certified, advice from real boat techs\u003c\/li\u003e\n    \u003cli\u003eSame-day shipping before 3 PM ET on in-stock items\u003c\/li\u003e\n    \u003cli\u003eNY headquarters and Fort Lauderdale flagship retail store\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003cdiv class=\"nvn-faq\"\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat does MDL mean on this fuse?\u003c\/summary\u003e\n    \u003cp\u003eMDL is a slow-blow, or time-delay, glass tube fuse. It tolerates a brief current spike at startup without blowing, then still opens the circuit on a real sustained overload. That makes it the right choice for motor and pump loads.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat's the difference between AGC and MDL fuses?\u003c\/summary\u003e\n    \u003cp\u003eAGC fuses are fast-acting and MDL fuses are slow-blow. They're the same physical 3AG glass cartridge and share the same holders, so they fit the same spots. The difference is how quickly they react. Use MDL for motors and pumps that have a startup surge.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWill these fit my Blue Sea ST Glass Fuse Block?\u003c\/summary\u003e\n    \u003cp\u003eYes. The 5232-BSS is made for Blue Sea Systems ST Glass Fuse Blocks, and it also drops into any standard AGC or MDL fuse holder, including inline holders on a single circuit.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eCan I use a 20 amp MDL on a 12 volt system?\u003c\/summary\u003e\n    \u003cp\u003eYes. These are rated up to 32 volts DC, which covers both 12 volt and 24 volt marine systems. The 32 volt figure is the maximum rating, not a requirement.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat are slow-blow fuses good for?\u003c\/summary\u003e\n    \u003cp\u003eLoads that draw a surge of current when they start, mostly motors and pumps. Blue Sea recommends these for pumps and other motor loads. A fast-acting fuse would often pop on the startup inrush, while a slow-blow rides through it and only blows on a true fault.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow many fuses come in the set?\u003c\/summary\u003e\n    \u003cp\u003eTwo. One for the holder and one for a spare. Keeping a backup aboard for each amperage you run is cheap insurance.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eMy fuse keeps blowing. Should I go up in amperage?\u003c\/summary\u003e\n    \u003cp\u003eNo. A fuse that keeps blowing is telling you the circuit is drawing more current than it should. Jumping to a bigger fuse removes the protection and can cook your wiring. Find out why the circuit is overloading instead, or give us a call.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eAre these glass tube fuses?\u003c\/summary\u003e\n    \u003cp\u003eYes, they're glass tube fuses in the 3AG size, the quarter-inch by inch-and-a-quarter cartridge. The glass body lets you see a blown element without a meter.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat amperage should I run for my pump?\u003c\/summary\u003e\n    \u003cp\u003eSize the fuse to protect the wire and match the load's rated draw. Check the motor's rating plate for its current draw, then pick a fuse that protects the circuit. If you're not sure, reach out and we'll help you spec it.\u003c\/p\u003e\n  \u003c\/details\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003ctable class=\"nvn-specs\"\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003cth\u003eTitle\u003c\/th\u003e\n\u003ctd\u003eBlue Sea Systems 5232-BSS 20A MDL Slow-Blow Glass Fuse (Set of 2)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\n\u003ctd\u003eBlue Sea Systems\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eManufacturer Part Number\u003c\/th\u003e\n\u003ctd\u003e5232-BSS\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eUPC\u003c\/th\u003e\n\u003ctd\u003e632085052324\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eFuse Type\u003c\/th\u003e\n\u003ctd\u003eMDL\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eFuse Action\u003c\/th\u003e\n\u003ctd\u003eSlow-Blow (Time-Delay)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eAmperage\u003c\/th\u003e\n\u003ctd\u003e20 Amp\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eVoltage Rating\u003c\/th\u003e\n\u003ctd\u003e32 Volts DC\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eFuse Construction\u003c\/th\u003e\n\u003ctd\u003eGlass Tube\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eFuse Size Standard\u003c\/th\u003e\n\u003ctd\u003e3AG (AGC \/ MDL)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eQuantity per Pack\u003c\/th\u003e\n\u003ctd\u003e2\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eCompatible Fuse Holders\u003c\/th\u003e\n\u003ctd\u003eBlue Sea Systems ST Glass Fuse Blocks, AGC and MDL holders\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eRecommended Loads\u003c\/th\u003e\n\u003ctd\u003ePumps and other motors\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\n    \"@context\": \"https:\/\/schema.org\",\n    \"@type\": \"FAQPage\",\n    \"mainEntity\": [\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What does MDL mean on this fuse?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"MDL is a slow-blow, or time-delay, glass tube fuse. 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The 5232-BSS is made for Blue Sea Systems ST Glass Fuse Blocks, and it also drops into any standard AGC or MDL fuse holder, including inline holders on a single circuit.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Can I use a 20 amp MDL on a 12 volt system?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Yes. These are rated up to 32 volts DC, which covers both 12 volt and 24 volt marine systems. The 32 volt figure is the maximum rating, not a requirement.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What are slow-blow fuses good for?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Loads that draw a surge of current when they start, mostly motors and pumps. Blue Sea recommends these for pumps and other motor loads. 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