Blower fuse

jddens · Post by **jddens** » Wed Mar 16, 2011 6:15 pm

On a friends boat with out any info...what amps should the blower fuse be?? Thanks......John

Stripermann2 · Post by **Stripermann2** » Wed Mar 16, 2011 6:58 pm

What boat are we talking about? On the 321 (32) the blower is limited to 15 amps via a circuit breaker in the switch, so...15 amps.
The 460 (36) is controlled by 20 amp fuse or circuit breaker.

So I imagine the max you'd want to go would be 20 amps.

Paul · Post by **Paul** » Wed Mar 16, 2011 7:21 pm

I have the factory blower in my boat ad it requires a 15A fuse

jddens · Post by **jddens** » Wed Mar 16, 2011 7:56 pm

Thanks, he has a house boat and absolutely no schematics or elec information, 15 should do it........John

Big D · Post by **Big D** » Wed Mar 16, 2011 10:36 pm

John, IMO it's not a good idea to assume anything when it comes to electrical. When I run into a similar situation (have on my old girl), I determine the current the exsisting wiring for that circuit is designed to carry. Find out the gauge and the distance (from supply to load and back), and this will tell you the maximum current draw allowed and the max rating of the circuit protection device (I build in a safety margin). With this info, you can look up charts available on line such as marinco.com. You don't want to make the mistake of installing a fuse that is rated higher than the wiring is rated for or else.

Charts available here: http://www.marinco.com/page/wire-tech-data

Paul · Post by **Paul** » Thu Mar 17, 2011 12:02 am

Good info Big D. Your correct in being cautious as to not overload the wiring. We should however keep in mind that these boats were generally wired with wire gauges that exceed the current requirements. That being said, if the fuse (or breaker) is chosen based on the max for the wire gauge, this value may actually much greater than the fuse requirements of the load itself and could cause damage to the load or even the boat.

John, if you have a DC current clamp available check the draw at start up on the blower. Be sure the blower is in good operating condition in order to trust the reading. Once you determine the draw, you can install a fuse one size higher and you should be good. As Big D stated though, be sure not to exceed the wire's rating.

jddens · Post by **jddens** » Thu Mar 17, 2011 6:34 pm

Thanks guys.....I do have an amp clamp and i can use that. I was on-board and looking for a quick reference. I'll be back there in a couple days to work on another issue and will bring the amp clamp and check it out....thanks again............John

RWS · Post by **RWS** » Thu Mar 17, 2011 8:42 pm

I had a blower problem like this years ago.

It wasn't the wrong fuse, but a short fuse that did her in.

RWS

Big D · Post by **Big D** » Thu Mar 17, 2011 10:22 pm

Paul, I agree; you most certainly should not fuse much greater than the load is rated at but we also can't stick a 20amp fuse in a circuit whos wiring can only handle 15 amps. I guess we should also ask; did the fuse blow? Why? Replacing with new blower? Too often I find people replacing such items like blowers, water pumps, bildge pumps etc. with bigger units because "it'll do a better job", only to forget that the bigger unit most likely draws a heavier load, and in some cases may be more than the wiring in the vessel for that circuit can safely handle.

kallen · Post by **kallen** » Sat Mar 19, 2011 10:12 pm

On my 81 f-32 each blower draws about 4.4 to 4.8 amps each on the same circuit. The fuse or breaker should be 15 amps. This allows power surges on start up.