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I have a 220V AC to 24V AC transformer rated at 2Amps. What size of Primary and Secondary fuse should I use?

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    \$\begingroup\$ What is the nature of the load you are protecting? Do you need slow-blow type fuses for inrush current tolerance? The fuse value is usually selected such that it allows for a small percentage more than the load will pull. \$\endgroup\$ – JYelton Apr 15 at 5:37
  • \$\begingroup\$ The transformer will drive 4 x valve actuators for a swimming pool (the manufacturer has not supplied the rating of the valves). They however are certainly well with the 2 amp maximum of the transformer and I doubt that there is any high initial demand. \$\endgroup\$ – user12231454 Apr 15 at 6:37
  • \$\begingroup\$ What are your fuses trying to protect? \$\endgroup\$ – Andy aka Apr 15 at 8:45
  • \$\begingroup\$ Generally need slow-blow for transformer input fuses due to inrush, otherwise you end up with an over-large fuse that can't protect the transformer. \$\endgroup\$ – Neil_UK Apr 15 at 9:48
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slow-blow 2A on the output, fuses take a very long time to blow at there rating, so this is mainly to protect against hard shorts,

If you're not pulling near the rating at any time, then conventional 2A

Mains input fuse depends on the quality of the transformer, plan for 0.5A, as cheaper transformers consume some current while doing nothing.

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