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I develop a home sprinkler controller, and would need a fuse. Traditional fuses (those glass cylinders with a wire inside) take too much space, and don't play well with SMD. My research found some poly fuses, including SMD poly fuses. However they seem to be for a small voltage (6-30V), and it is unclear whether they will burn if overvoltaged (think main connection or lighting strike). It is also unclear whether they can handle significant inductive load such as sprinkler solenoid connected via a long cable.

What are the honorable community members using nowadays in lieu of glass fuses? Is there a better alternative to the "traditional" glass fuse?

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    \$\begingroup\$ A plastic fuse. or ceramic. Or bare. \$\endgroup\$
    – Passerby
    Commented Jul 11, 2017 at 5:32
  • \$\begingroup\$ Resettable fuses may work. Check \$\endgroup\$
    – Sachin
    Commented Jul 11, 2017 at 7:26

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Traditional fuses ... don't play well with SMD.

You're misinformed. There are plenty of SMD fuse holders available for that kind of fuse.

There are also smaller fuses with similar behavior (i.e. disposable rather than resettable like a polyfuse) available with SMD holders.

However they seem to be for a small voltage (6-30V),

Fundamentally, for a fuse to be able to withstand hundreds of volts in its fused (broken) state, there must be a certain distance between its terminals. There is a fundamental trade off between size and voltage rating here. So you need to decide your actual voltage requirement and then look for the smallest fuse that will support it.

it is unclear whether they will burn if overvoltaged (think main connection or lighting strike)

You should not be using a fuse to protect against over-voltage. Fuses protect against over-current, not over-voltage. And you should not expect a fuse to protect the fused device either --- the fuse is there to prevent over-heating from causing a fire. It is not intended to prevent damage to the fused device.

It is also unclear whether they can handle significant inductive load such as sprinkler solenoid connected via a long cable.

Typically inductive loads don't cause high currents, so they wouldn't be likely to overload a fuse. (You could, of course, contrive a circuit where an inductive load generates a high current. I'm speaking of typical scenarios)

They may cause high voltages when switched quickly. You should use an over-voltage protection device or a free-wheel device to protect against this. Not a fuse.

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  • \$\begingroup\$ A fuse is in line to protect the cable from burning in case the solenoid shortens out, or someone messes up with connections. My concern is overvoltage coming back when inductive load is disconnected, which might damage the fuse as the solenoid inductivity is significant. \$\endgroup\$
    – George Y.
    Commented Jul 11, 2017 at 6:00
  • \$\begingroup\$ @GeorgeY. in the answer by The Photon he wrote : "They may cause high voltages when switched quickly. You should use an over-voltage protection device or a free-wheel device to protect against this. Not a fuse." So how are you going to use his advice? \$\endgroup\$
    – Solar Mike
    Commented Jul 11, 2017 at 7:35
  • \$\begingroup\$ @GeorgeY., It depends a lot on exactly what your circuit is, but in many (most?) cases, the over-voltage from inductive kick-back would damage whatever is driving the other end of the fuse before it damages the fuse. If you have a specific use case in mind, maybe ask a new question, with more details about the driver circuit and load, asking about how to protect from over-voltage. First search the archives for other questions about inductive loads and see if your question is already answered. \$\endgroup\$
    – The Photon
    Commented Jul 11, 2017 at 14:23

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