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Wire sizing for relay box daisy chains

EFI Wiring Fundamentals

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I feel I've been over thinking this and got myself in a tiz with it.

First off, my fuse/relay box isn't a branded one and doesn't come with a busbar(banded ones seem to be impossible to buy in the UK) so I need to daisy chain the power feeds and also need to daisy chain the fuses from a relay supplying 4 fuses.

How do i go about sizing the wires for them? Do the links between the relays need to be big enough to cover the biggest fuse or the total fuses.

I must have gone around in circles with this 10 times tonight

The fuse is there to protect the wire. The wire is there to support the electrical load. So size the wire for the load. If you are combining multiple loads into a single feed wire (daisy chained or spliced into one feed), then the feed wire needs to be the sized to the total of all loads that pass through it.

If you did want to daisy chain say 4 relays/fuses (i.e. circuits) all of the same size, you could use a 4x feedwire, 3x to the 2nd circuit, 2x to the 3rd circuit, and base size for the last circuit.

Hope that helps your puppy sleep at night.

See I've kind of been following this from the course as a basis for my loom

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