Determining If A 30 Amp Case Fuse Is Blown

Updated 02/22/2021 | Published 02/18/2021

Question:

how do you test the 30 amp square pink fuse that has no external contact point on either side?

asked by: Dan

Expert Reply:

On a square-shaped sealed fuse (case fuse) you typically do not have leads or contact points to test the fuse, as you mentioned. In this case, you usually can see through the top clear section to verify if the fuse is blown (separation of the internal circuit). If you cannot tell using this method, then you use a voltmeter on the lowest resistance (Ohm) setting and connect the two voltmeter leads together and record this reading. Then connect the two voltmeter leads to the contact points on the bottom of the fuse; make sure the fuse is fully removed from any circuit/power. You should have continuity and there should be a very similar resistance reading to what you measured when you touched the voltmeter leads together. If this is not true when you test for resistance then the fuse is blown and needs replaced.

expert reply by: Andrew N