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Always Hot Battery Bus

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Timandmeli

Joined: 31 Dec 2008
Posts: 1
Location: Southeast Alabama

Posted: Wed Dec 31, 2008 1:48 pm Post subject: Always Hot Battery Bus

I'm wiring my rv-8 using bob nuckolls simple vfr day night wiring diagram.  Provisions are for a always hot battery bus.  He indicates the length of wire should be six inches or less.  However I would like to mount this fuse block next to the main bus which is one bulkhead forward of the instrument panel requiring a 5 foot length of wire.  Should I fuse protect this wire with in-line fuse or maybe a current limiter.  I'm planning on one electronic ignition and one conventional magneto.  Thanks    Tim

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_________________
Tim Pethel
RV-8A
Wiring Fuse

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Dec 31, 2008 2:41 pm Post subject: Always Hot Battery Bus

At 03:48 PM 12/31/2008, you wrote:

 	  Quote: 	
		  

<timandmeli(at)roadrunner.com>



I'm wiring my rv-8 using bob nuckolls simple vfr day night wiring 

diagram.  Provisions are for a always hot battery bus.  He indicates 

the length of wire should be six inches or less.  However I would 

like to mount this fuse block next to the main bus which is one 

bulkhead forward of the instrument panel requiring a 5 foot length 

of wire.  Should I fuse protect this wire with in-line fuse or maybe 

a current limiter.  I'm planning on one electronic ignition and one 

conventional magneto.  Thanks    Tim


	


    The 6" rule including the maximum size of fuse (7A)

    for the hot-battery bus is a convention adopted for

    post crash fire risk reduction. It's not possible

    to offer advice based on any analysis of your

    proposed changes. If you mount it that far away

    from the battery, you've got an always hot feeder

    rated for considerable current capability. This

    is not done in the certified world. I would

    recommend you leave the battery bus fuse block

    co-located with the battery contactor and

    run individual feeders from fuses of no more

    than 7A from that location.

        Bob . . .



         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------

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pwmac(at)sisna.com
Guest

Posted: Wed Dec 31, 2008 4:19 pm Post subject: Always Hot Battery Bus

Long hot wires bother me as well.

However in the world of off road truck racing there is no room for a 

battery located near the panel or engine. We frequently use 10'+ #2 

always hot unprotected leads from 2 big AH batteries located in the 

back where the weight does some good. Its very rare to have any 

issues after a major crash that involves shorted battery leads. You 

better believe the leads are carefully routed and protected. 

Typically protected with the convoluted split plastic stuff. Sure it 

burns but it is good for abrasion protection and cheap. The best lead 

wire is welding wire with double elastomer insulation. Pretty 

durable. I cannot source the stuff for you all but a day of shopping 

at the weld  & battery shops will turn up a good product. I use a 

west marine source 4 position switch to turn the power off if need be 

and for storage to reduce the drain from all the parasite 

electronics. Yes the switch is where the driver can reach it and it 

is a long ways from the batts.



The bottom line is there are many more high risk things in a plane or 

a race truck to be concerned about than a long hot batt lead.

Regards, Paul

================



At 03:39 PM 12/31/2008, you wrote:

 	  Quote: 	
		  

<nuckolls.bob(at)aeroelectric.com>



At 03:48 PM 12/31/2008, you wrote:

>

><timandmeli(at)roadrunner.com>

>

>I'm wiring my rv-8 using bob nuckolls simple vfr day night wiring 

>diagram.  Provisions are for a always hot battery bus.  He 

>indicates the length of wire should be six inches or less.  However 

>I would like to mount this fuse block next to the main bus which is 

>one bulkhead forward of the instrument panel requiring a 5 foot 

>length of wire.  Should I fuse protect this wire with in-line fuse 

>or maybe a current limiter.  I'm planning on one electronic 

>ignition and one conventional magneto.  Thanks    Tim



    The 6" rule including the maximum size of fuse (7A)

    for the hot-battery bus is a convention adopted for

    post crash fire risk reduction. It's not possible

    to offer advice based on any analysis of your

    proposed changes. If you mount it that far away

    from the battery, you've got an always hot feeder

    rated for considerable current capability. This

    is not done in the certified world. I would

    recommend you leave the battery bus fuse block

    co-located with the battery contactor and

    run individual feeders from fuses of no more

    than 7A from that location.

        Bob . . .



         ---------------------------------------

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

         ---------------------------------------

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

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