Circuit Breaker v. AMG fuse and holder

[mr110]

Hi All.

I am wondering if anyone has any knowledge about the pros and cons between these two. I am using them between by 3G alternator and starter solenoid as recommended in the Painless instructions.

I currently have a 150 amp AMG fuse and Bussman holder. I noticed that the holder isnt well covered and it required 5/16th lugs which are a little annoying as everything else is 1/4".

Yesterday i was shopping for lugs and i ran across this Bussman water proof circuit breaker, rated for the same 150 amp and with 1/4" lug requirement for wires.

Will the circuit breaker work? or is there a reason the AMG fuse is used more often (if that is a true statement i dont know)

This is the fuse holder i have:

This is the circuit breaker i found and a link:

http://www.autozone.com/electrical-...er/cooper-bussmann-circuit-breaker/32369_0_0/

 

[pcf_mark]

I use these from a Ford Expedition. OEM quality, can get them anywhere, $2 at the pick n pull. That is the starter solenoid on the firewall you can grab that too with all the wiring and ends ready to go if you are using a later model starter.

http://www.ford-trucks.com/forums/1428808-mega-fuse-holder.html

 

[Viperwolf1]

How many times are you planning to install it? I don't understand what the hardware size has to do with anything.

You shouldn't need a breaker there. You really don't want the fuse or breaker to open when the alternator is working because it can damage the alternator. Size it correctly and you will be fine.

 

[mr110]

How many times are you planning to install it? I don't understand what the hardware size has to do with anything.

You shouldn't need a breaker there. You really don't want the fuse or breaker to open when the alternator is working because it can damage the alternator. Size it correctly and you will be fine.

Im going to be moving the wiring around in the future, and then remaking the cables to fit the new placement. So buying all 1/4" would just make life simpler for me.

Im following the instructions for the painless alternator swap.

 

[Justafordguy]

I see no reason the breaker wouldn't work just fine. I use that style breaker on my RV for the hydraulic system and have never had any issues with them.

 

[Steve83]

...the holder isnt well covered...

Attempting to waterproof automotive electrical components is a really good way to make them HOLD water.



An electrical cover should only prevent accidental metal-to-metal contact; it should be WELL ventilated so it can drain & then dry. That's how these OE electrical parts are built:

. .

...and it required 5/16th lugs...

That's because it's built to handle higher fuses, and the connection has to be designed to handle more current than the biggest fuse that might go in, OR the cables necessary for that biggest fuse.

...water proof...

Not forever, if at all.

...circuit breaker, rated for the same 150 amp and with 1/4" lug requirement for wires.

The breaker has only 1 rating, so its terminals can be sized just for that rating.

Will the circuit breaker work?

Probably for a while.

is there a reason the AMG fuse is used more often...

More robust; more reliable; more versatile, less expensive, easier to replace...

You really don't want the fuse or breaker to open when the alternator is working because it can damage the alternator.

Circuit protection isn't there for when things are working; it's there for when things fail. For an alternator; it's required primarily for collision (when the sheet metal might cut into the alternator output wire); but also in case the alternator diodes fail or other catastrophic internal failure. In any of those cases, damage to the alternator is moot. If the protection is sized properly, it WON'T open when the alt is working.

 

[Broncobowsher]

Fuse - simple
Circuit breaker. Lots of moving parts. Coil (or heating element depending on design) moving plunger, trip mechanism, spring(s)...
My home circuit breaker I can trip by just giving them a think to the palm of my hand.

If the breaker pops (or fuse blows) while the alternator is building a huge charge the spike from the circuit suddenly opening can blow the diodes in the alternator. You never want the circuit to open under load, only in the case of severe failure (dead short). New cars and trucks have fuses now so in a wreck and something shorts out, the circuit opens and you don't get a post accident electrical fire. That's also why they are right at the battery.