Can fast blow fuse used in place of slow blow fuse?

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1135506

2026-04-23 09:15

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No. A slow blow fuse is intended to survive a short overload from the startup of a piece of equipment, usually a motor or power supply. If you use a fast blow fuse in this application, it will tend to blow unexpectedly.

Motors usually pull four times their rated running current on startup, but only for a very short period of time. The slow blow fuse, or slow trip circuit breaker, is designed to handle this. Similarly, power supplies need to charge the primary filter capacitor from zero voltage in one line cycle on startup. Worst case is turning on the power switch at the peak of the line cycle. Inductance of the transformer (if present) and dynamic resistance of the diode mitigates this, but there is still a larger than normal current transient. Again, the slow blow protective device allows this in the short term.

Hy i'm GbRlEuEeN, i used f10a(fast) fuse to replace t5a fuse(slow) but was on audio sistem(subwoofer) and i will change back as soon il get the t5a. ( i tryed f5a first but blowed instant at power up.

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