Okay, I need to buy either a fuse, fusible link or breaker for my MK VIII fan install. I'd like to use a breaker used for sound system installs but I'm not sure about which size is needed or if this is a good idea. I am going to use a starter relay with my existing Permacool controller to keep the auto on and off function. From what others have posted this fan can draw 100 amps on initial startup but settles to around 40 amps. If I use a fuse or fusible link what size should I use?

Thanks

Todd.

A 50 or 60 amp. Its better to be to small than to big. That 100 amps on start up is only for a micro second, which shouldn't blow the fuse. All electric motors draw more on start up.

What kind of starter relay are you going to use? Most starter relays aren't rated for continuous duty. I'd use a fusible link like most manufacturers do, one that is 2 sizes (4 numbers) smaller than the fan wiring.

What kind of starter relay are you going to use? Most starter relays aren't rated for continuous duty.

I didn't know that about starter relays, I was thinking about a F#*d starter solenoid.

If you want a heavy duty relay like that, go to Cole-Hersee.

http://www.ryderfleetproducts.com/cgi-bin/ryderfp/products/srm/oid/51832/erm/product_detail.jsp

Continuous duty solenoid is what I'll use,


Thanks

Somehow the notion of using a small wire ANYWHERE in a high current circuit just does not make any sense to me at all. The only reason I can see to use a fusible link is because it could be placed right at the battery.

Much much better to use a easily replaceable fuse for this application. In fact I would probably stick with the fuse over the circuit breaker because of the startup inrush current. If the fan truly does pull 40A I would wire it for 50-60A and fuse with a maxi ATM fuse accordingly.

Be sure to wire from alternator power source and not battery though as that is where the current is really feeding from.

http://cgi.ebay.com/8-Gauge-MAXI-Fuse-Holder-with-FREE-50-AMP-FUSE_W0QQitemZ200256300526QQcmdZViewItem?hash=item 200256300526&_trkparms=72%3A1421%7C39%3A1%7C66%3A2%7C65%3A12%7C 240%3A1318&_trksid=p3286.c0.m14

Will a 50 amp fuse blow with an initial 100 amp draw when the fan kicks on?

No. That 100 amps on start up is only for a micro second, which shouldn't blow the fuse.

I'd like to use a breaker used for sound system installs but I'm not sure about which size is needed or if this is a good idea.

Most breakers act like a slow blow fuse. See the TIME VS. PERCENT OF RATED CURRENT chart in this link (http://www.cooperbussmann.com/pdf/d70101c3-1921-456a-8cdd-cdbe1fc8a85b.pdf). A 50 amp breaker pulling 100 amps would take somewhere between 10-30 seconds to trip the breaker.