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This washer will get EXTREMELY HOT 🥵| Ask The Expert with NIGEL CALDER
August 30, 2025 · 2 min · 5K views
What this video covers
Stainless steel washers or bolts in a conducting path act as resistors under load, generating heat that can melt fuse holders, trigger thermal fuses, and destroy alternators.▶ 1:29 Nigel Calder explains that stainless steel is a poor conductor, so its presence in a live circuit creates resistance invisible to a voltmeter when the circuit carries no load — the voltage drop only appears under load.▶ 1:28 The danger escalates in high-current circuits: Calder cites multiple confirmed cases where stainless steel washers at ANL fuse holders transferred enough heat into the fuse to blow it thermally while alternators were running hard, destroying the alternators.▶ 2:01 The fix is straightforward — stainless steel fasteners are acceptable for clamping terminals mechanically, but copper or tinned-copper hardware must carry the current.▶ 1:16 Jan Attenstedt notes the topic is covered in the BoatHowTo BoatElectrics 101 course at BoatHowTo.com.▶ 2:30 Testing a suspect connection with a voltmeter only reveals the fault when the circuit is under load.▶ 0:49
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