are some fuses switched on with the key?

Hi:

I installed a Western Snow plow on the 2003 F-250.  Part of the install required that I get power from a free spot in the fuse panel.  I plugged a fuse, with a wire harness, into a spare slot.  The fuse is powered whether the key is turned on or not.  I'd prefer that the circuit only be powered when the truck is running, or at least when the key is turned to the accessory position.  Are some fuse positions only powered when the key is turned?  Thanks. :)

Yes there are some fuses that only get power with the key.  You will have to use a volt meter to find such a fuse.  There may be one labeled Radio,

Thanks.  Too bad they aren't labelled as "switched" in the owner's manual.  I'll use a meter to locate one. :-)

Go to the input side i.e. before the fuse then separately fuse, or ign wire at the steering column, then switch then to a relay with direct battery power because I think this is going to consume loads of amps.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Sorry.  I didn't notice the last post until today.

Why are you thinking it'll take 'loads of amps'?  It's just the circuit to energize the relay.  Any power the plow uses when the relay in energized goes directly from the battery, through the relay, then to the plow.  Am I misunderstanding something about how relays work?

Thanks.

My apologies, I was testing your knowledge because this is actually your first mention of a relay.
Since you've belatedly mentioned it of course your power handling at the switch will be less than 2 amps.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Opps.  No need to apologize.  I hadn't realized I didn't mentioned the relay in the original post.  I guess it wasn't crucial to that post, but it would have certainly made things clearer.    When I uninstalled this plow (I bought it used and had to uninstall myself) the power feeding the relay was through fuse tap on a 30A mini.  I was wondering why such a large fuse was used (being cautious I suppose). 

Thanks for the replies.

That's OK, didn't know your knowledge levels and I couldn't assume, also in a foul mood 'cause my lot just lost a big big soccer match to bad reffing. HDTV and live makes it worse.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

To sum up:-
Ground to switch to relay 85.
86 to ignition available under hood, e.g. wiper feed u/hood fuse box, spur to the input via a 3amp fuse.
Battery to 87 via a 30* amp fuse.
Plough to 30.
*Or the plough rating + 5 amps.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Nice to see amicable clarifications and interchanges.

Clever people use relays. Apart from being able to add to almost any circuit without adding significant load [ie, coil energising current is typically ~250mA, but up to (say) 2A for BIG relays (aka contactors and solenoids)], it allows the heavy power to be taken independently (and cleanly) from a new battery-fuse circuit. (Yet still be "controlled" via whatever switched "source" - eg, IGN, ACC, manual...)

Not that Howie is clever - he's far more than that. [ IMO he's "unobtanium" - way above his mere Platinum rating. (Oh - it's still merely Gold...) But Howie is also a Gem, and a true Gentleman (not that that means he takes prisoners!) ]

Thanks everyone. :-)