Basic circuit with relay

Question

Hi. First of all: I hope this is the place to post. I am gonna make an easy circuit with a relay to control a pump.(see attachment) I understand the principal, but I wonder if there is anything more I gotto think of, like resistors or something? It is not to be used in a car. I am thinking of using an car relay: 12V, Max 30 amp. The pump use 12V and 4 amp. The fuse need to be 4 amp? Can the switch for example be wired directly to pluss and minus on the car battery or do I need a resistor there? Thanks! 
 Attachments:

dougw · Answer

The circuit is good the way it is.

The fuse could be a little higher current - 5 to 10 amps, as long as the wiring and connectors can survive whatever current the fuse allows.

The switch/relay power could be connected at the output of the fuse to protect the relay and switch as well.

You could use (large) snubber diodes across the relay coil and pump to minimize arcing on the switch and relay contacts.