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Relay trigger ampage.

EFI Wiring Fundamentals

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Discussion and questions related to the course Motorsport Wiring Fundamentals

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I want to trigger the main power relay in the boot from the ignition switch on the dashboard a distance of 4.5 meters. (14.7ft)

From the Internet I've found this:

'The current draw of the coil is not normally shown but is typically 150-200 mA.'

Using wirebarn's voltage drop calculator.



1amp current(instead of 200mA)

wire length of 4.5m 14.7ft

=22 awg.

The question I have is. Even though the calculator requires a cable of 22awg do you think that it's best to up the cable size 1-2 sizes or leave it like it is?


22AWG will be good enough to trigger a relay at this distance.

It'll depend on the specific relay, but that should be fine - it you can post the relay in question, we may be able to find the minimum operating voltage.


Thanks for your reply’s.

Gord, I intend to run micro relays like in the attachments. I hope that helps.


Attached Files

If the relays are reputable, you should be fine.

We usually reply within 12hrs (often sooner)

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