Would you install a ANL 50amp fuse

[ron sterba]

Was considering installing a fuse holder on my 9A firewall with a 50 amp fuse that would feed my main buss in the cockpit. This fuse holder would be installed near my Master relay, on the engine side of the firewall. Has anybody done this? What kind of fuseholder/ block would you use. I saw one on a firewall once that was about 3" long in black color & with a plastic clear cover. It had a 50 amp fuse. I believe they call them ANL fuse? Quarter inch hole on one end and a "U" shape on the other. My condition inspection is due shorty. Any ideas always appreciated. Thanks

Ron in Oregon RV9A N421HJ just one away from the Honda Jet and a whole lot more fun to fly! Course unless you are in a hurry.

[vic syracuse]

What you described works fine. B&C specialty has pictures of them on their website.

http://www.bandc.aero/anlcurrentlimiterbase-1.aspx


Vic

[bret]

I have three 80 amp ANLs, one from the B+ PP 70 amp alt, another one to feed the plane after contactor, and one at the backup 20 AH battery.

[Deweyclawson]

It sounds like this would be a serious failure if it occurred in flt. I think I would want it accessible if it blew in flt.

[vic syracuse]

It is common practice to put these on the firewall so you don't have a hot, unprotected B-lead running directly into the cockpit, as was practiced for many years.

If you have a 60 amp alternator, use an 80 amp limiter. I have never had one blow. They are very slow to blow, not like a CB or normal fuse, and are there to mainly protect against a dead short.

I highly recommend using one. Have been doing it for many years, as have others.

Vic

[DanH]

Plus one on everything Vic says.

Originally Posted by vic syracuse

It is common practice to put these on the firewall so you don't have a hot, unprotected B-lead running directly into the cockpit, as was practiced for many years.

If you have a 60 amp alternator, use an 80 amp limiter. I have never had one blow. They are very slow to blow, not like a CB or normal fuse, and are there to mainly protect against a dead short.

I highly recommend using one. Have been doing it for many years, as have others.

Vic

[RicoB]

I have a plane &power 60amp alternator I used a 60amp ANL, is that the wrong amperage?

[AlexPeterson]

Originally Posted by RicoB

I have a plane &power 60amp alternator I used a 60amp ANL, is that the wrong amperage?

Should be ok - have a look at the specific data sheets for that fuse, it will show the time to open vs current.

I used this brand - it shows as a minimum opening time at full rated of about 4 hours..., max opening time at rated of infinity. They are designed to be matched to the alternators. 120s opening time minimum, 30 minutes maximum, at 135% of rated.

http://www.littelfuse.com/~/media/au..._datasheet.pdf

That brand is about $7 plus a couple dollars shipping from Digikey.

[Captain Avgas]

I do not think that Bob Nuckolls recommends a fuse ( or ANL limiter) on the power supply from the master to the main bus. He states his reasons for this in the AeroElectric Connection Manual. He does however recommend one be used at the firewall end of the alternator B lead. This "fuse" must obviously be rated beyond the maximum current output of the alternator. This "fuse" is to protect the alternator (and the B-lead running from the alternator) in the event that there is a short to ground in the diodes at the alternator resulting in a full battery current surge to the alternator.

Having said that I do believe there are obvious very real pitfalls in discussing these type of electrical architecture decisions on VansAirforce without reference to an actual drawing. Too easy for novices to get confused.

[DanH]

Originally Posted by Captain Avgas

I do not think that Bob Nuckolls recommends a fuse ( or ANL limiter) on the power supply from the master to the main bus.

I can think of both pros and cons, but tell us why Bob doesn't like it.

He does however recommend one be used at the firewall end of the alternator B lead. This "fuse" must obviously be rated beyond the maximum current output of the alternator. This "fuse" is to protect the alternator (and the B-lead running from the alternator) in the event that there is a short to ground in the diodes at the alternator resulting in a full battery current surge to the alternator.

It just protects the airplane. The B-lead is running through the engine compartment, an area full of hot and vibrating things. Short the B-lead through worn or melted insulation, or break it away from the B-terminal, and it can short to almost anything in the compartment with full battery amps.