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Engine compartment fuse?

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yellowduckduo(at)gmail.co
Guest

Posted: Mon Nov 02, 2020 7:14 am Post subject: Engine compartment fuse?

Are there any industry acceptable 30 amp fuses or circuit breakers for 

installation on the engine side of the firewall?

Other than a large ANL current limiters I've never noticed fuses or 

C/B's in an engine compartment.  I am aware of ambient temperature 

effects on current limiting devices.



Short story: This is for a 912iS install with the battery and voltage 

regulator in the engine compartment and should be something that won't 

raise concern from a Transport Canada inspector.  At the minimum I'd 

like to run the wire between the battery and the voltage regulator 

entirely within the engine compartment but it needs 30 amp protection.

thanks

Ken

jluckey(at)pacbell.net
Guest

Posted: Mon Nov 02, 2020 8:11 am Post subject: Engine compartment fuse?

Ken,

Look at the LittleFuse MIDI line of fuses...

https://www.littelfuse.com/products/fuses/automotive-aftermarket-products/bolt-down-fuses/midi-boxed.aspx



-Jeff

                  

                                                                    On Monday, November 2, 2020, 07:26:22 AM PST, C&K <yellowduckduo(at)gmail.com> wrote:                 

                 



                 



                 --> AeroElectric-List message posted by: C&K <yellowduckduo(at)gmail.com (yellowduckduo(at)gmail.com)>



Are there any industry acceptable 30 amp fuses or circuit breakers for 



installation on the engine side of the firewall?



Other than a large ANL current limiters I've never noticed fuses or 



C/B's in an engine compartment.  I am aware of ambient temperature 



effects on current limiting devices.



Short story: This is for a 912iS install with the battery and voltage 



regulator in the engine compartment and should be something that won't 



raise concern from a Transport Canada inspector.  At the minimum I'd 



like to run the wire between the battery and the voltage regulator 



entirely within the engine compartment but it needs 30 amp protection.



http://forums.matronics.comp;       - NEW MATRONICS LIST WIKI -



http://www.matronics.com/contribution====================

user9253

Joined: 28 Mar 2008
Posts: 1925
Location: Riley TWP Michigan

Posted: Mon Nov 02, 2020 12:25 pm Post subject: Re: Engine compartment fuse?

The Rotax 912iS engine comes with a fuse box that is mounted on the

engine side of the firewall.  It contains many ATC and Mini fuses.

If Rotax uses them, then so can we.

If a fuse nuisance blows due to ambient temperature, use one size larger.

Could your engine be a 912ULS?

_________________
Joe Gores

rparigoris

Joined: 24 Nov 2009
Posts: 792

Posted: Mon Nov 02, 2020 1:09 pm Post subject: Re: Engine compartment fuse?

Hi Ken FWIW I just installed a 30 amp MIDI fuse on my Rotax 914. I punched out the hole of the MIDI to 1/4"and mounted one side to my shunt and the other side to a 1/4-28 Brass stud so a holder was not needed. McMaster and B&C sells MIDI holders. Note that MIDI and Maxi fuses are not as fast acting as ATC and MINI. Maxi fuese are large ATC like fuses. McMaster sells the inline fast on style holder as well as a more robust clamp style holder. I was on the fence between MIDI and Maxi. Ron P.

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Nov 02, 2020 1:59 pm Post subject: Engine compartment fuse?

At 10:06 AM 11/2/2020, you wrote:

  	  Quote: 	
		  Ken,



 Look at the LittleFuse MIDI line of fuses...



  https://www.littelfuse.com/products/fuses/automotive-aftermarket-products/bolt-down-fuses/midi-boxed.aspx 	


   These things require a mounting block which

   might not be a bad thing if it adds a fat-wire

   distribution point. But a MAXI holder butt-spliced

   into the feeder would work too and much less

   fuss. Here's a link to the data sheet

   .pdf download



  https://tinyurl.com/y3h5wj4o



   It can be tied into a wire bundle but has

   a hole for mechanical mounting if that

   seems more elegant. The holders are

   liquid tight.



   Both holders and fuses are available at

   most carparts emporiums. 



 



 

 

   Bob . . .

rparigoris

Joined: 24 Nov 2009
Posts: 792

Posted: Mon Nov 02, 2020 11:46 pm Post subject: Re: Engine compartment fuse?

Hi Ken Here's a McMaster MIDI Fuse Holder: https://www.mcmaster.com/fuse-holders Note McMaster can order you a 30 amp MIDI or you can buy a 30 amp and holder from B&C, here's a pretty robust McMaster Maxi fuse holder: https://www.mcmaster.com/maxi-compatible-fuse-blocks Ron P.

johnbright

Joined: 14 Dec 2011
Posts: 165
Location: Newport News, VA

Posted: Tue Nov 03, 2020 7:18 am Post subject: Re: Engine compartment fuse?

This may be more than what the OP was asking but I made notes for myself and I'll share them here.



Speaking of bolt-down fuses and current limiters, from what I have seen there are three bolt center-to-center distances: 61 mm, 2", and 30 mm.



B&C shows only 61 mm on their website: Bussman ANL current limiters and their holders.



61 mm centers:

Bussman ANN 10 to 800 A fast-acting current limiters.

Bussman ANL 35 to 750 A current limiters. I gather ANL is originally a Bussman term that has been co-opted by others.

Renology ANL 61 mm fuses. Renology calls it a fuse and it looks about as fast as an ANN fast-acting current limiter.



2" centers:

Bussman AMG 100 to 300 A fuses.

Littlefuse MEGA 40 to 100 A fuses.



30 mm centers:

Bussmann AMI 30 to 150 A fuses. Seems to be practically the same as MIDI.

Littelfuse MIDI 23 to 200 A fuses.

Littlefuse BF1 23 to 200 A fuses. Seems to be practically the same as MIDI.

Various offerings of fuses under the generic name MANL, mini ANL.



When fusess are listed as MEG they mean MEGA.

_________________
John Bright, RV-6A, at FWF, O-360
Z-101 single batt dual alt SDS EM-5-F.
john_s_bright@yahoo.com, Newport News, Va
N1921R links

yellowduckduo(at)gmail.co
Guest

Posted: Wed Nov 04, 2020 6:00 pm Post subject: Engine compartment fuse?

Joe and Ron  thanks for your thoughts

It is the 912i with the large rotax supplied fuse box. (The rotax 

supplied fuse box with voltage regulators that rotax says must be 

located in the engine compartment due to fire risk but must be kept 

below 80 Celsius). From an inspectors point of view an an 

automotive/marine fuse block is probably not quite as acceptable as a 

rotax supplied fuse box but it may be an option.  A 10awg wire feed from 

the battery contactor hardly seems like a classic "fat wire" that 

doesn't need current protection but I could upsize it and that may be 

the easiest solution.  It would mean a total of three 30 amp fused wires 

passing  back through the firewall to the rotax voltage regulator/fuse 

box in the engine compartment.



In the past I've used a maxi fuse holder on the cold side of the FW.  I 

did not know about the midi fuses.  Most fuse holders seem to be good 

for only about 85*C. but that also seems true for the rotax supplied box.

Ken

On 02/11/2020 4:09 PM, rparigoris wrote:

 	  Quote: 	
		   



 Hi Ken FWIW I just installed a 30 amp MIDI fuse on my Rotax 914. I punched out the hole of the MIDI to 1/4"and mounted one side to my shunt and the other side to a 1/4-28 Brass stud so a holder was not needed. McMaster and B&C sells MIDI holders. Note that MIDI and Maxi fuses are not as fast acting as ATC and MINI. Maxi fuese are large ATC like fuses. McMaster sells the inline fast on style holder as well as a more robust clamp style holder. I was on the fence between MIDI and Maxi. Ron P.





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=499206#499206

user9253

Joined: 28 Mar 2008
Posts: 1925
Location: Riley TWP Michigan

Posted: Thu Nov 05, 2020 6:14 am Post subject: Two Fuse Option

Attached is a schematic using only two fuses.

Rotax X3.png

Description:

Filesize:

10.77 KB

Viewed:

4598 Time(s)

_________________
Joe Gores

yellowduckduo(at)gmail.co
Guest

Posted: Thu Nov 05, 2020 10:02 am Post subject: Engine compartment fuse?

thanks Joe

It's tough for me but as a new rotax guy I'm trying to just assimilate 

into the rotax culture and follow their advice rather than fight it and 

do what seems logical since we don't really know what failures or 

situations they are trying to cater to.  One possible drawback for 

eliminating one of those fuses is that if the start power fuse pops 

after the engine has cranked just enough to keep going (rare but not 

unknown) it would disable backup power for the flight so I thought I'd 

keep all three 30 amp fuses.



I do plane to  use a start power relay similar to the rotax blessed 

rs-flight system which at least means the start power won't have to go 

to a switch on the instrument panel.



I will add over voltage protection since despite verbal claims otherwise 

the current install manual actually says "5. Attention: In failure 

conditions the output voltage can exceed the specified limits"



thanks and keep the ideas coming

Ken



On 05/11/2020 9:14 AM, user9253 wrote:

 	  Quote: 	
		   



 Attached is a schematic using only two fuses.



 --------

 Joe Gores





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=499261#499261





 Attachments:



 http://forums.matronics.com//files/rotax_x3_896.png

user9253

Joined: 28 Mar 2008
Posts: 1925
Location: Riley TWP Michigan

Posted: Thu Nov 05, 2020 10:19 am Post subject: Re: Engine compartment fuse?

Having a momentary start enable switch could be advantageous by making it 

more difficult for unauthorized people (kids) to start the engine.

_________________
Joe Gores

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