I don't know what the current capacity of the switch is but strongly recommend using relays anyway. There's a few good reasons why OEM setups are done that way.
Read on if you want, but I do tend to get wordy...
- you can run your relay coil grounds to the switch and then a short wire to earth at the switch, so less wiring and less high current wiring to your dash
- filament globe lights are an inductive load at startup which means a current spike at turn on that causes arcing and reduced life of your switch contacts
- relays are easily replaced in the unlikely event they wear out, and 30A+ relays are cheap and will handle the 10 or 20A load of your lights without issue
- relays open and close their contacts more quickly than a switch reducing arcing at turn on/off
- the relay is ideally close to the main lights meaning shorter power runs and less voltage drop in the wiring giving you brighter lights (I always use much heavier power feeds than I need to for this reason also, wire is relatively cheap and if I upgrade lights the wiring is already good to go
- I work for a company that makes onboard battery chargers/isolators etc. and most customer issues are caused by shortcutting the installation, they try to cheap out on the simple stuff and it works when they test it but fails when they need it in the middle of nowhere
Cheers,
D
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