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Facet Fuel pump amperage

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jeffrey_davidson(at)earth
Guest

Posted: Sun Apr 06, 2008 3:53 pm Post subject: Facet Fuel pump amperage

I'm using the Facet 40105 fuel pumps in my leading edge fuel tanks only fuel system.  I wired up the pumps today and tested them for the first time.  According to Facet/ Purolator, they should draw .75 to 1 amp.  With 1 amp fuses on each both pumps promptly blew the fuses on their separate circuits after a few seconds.  I put in 2 amp fuses and both would run OK.  Looking at the archives, there was a lot of discussion about this in the 1999 and 2000 time frame.  Since the documentation seems to be inaccurate, what size fuse or breaker are those with this pump using: one, two, three, or five amp fuses?  Thanks ….  

   

Jeff Davidson  

CH601-HD/Jabiru 3300A  

Gonna' finish sometime!  

   

   

       [quote][b]

Terry Phillips

Joined: 11 Jan 2006
Posts: 346
Location: Corvallis, MT

Posted: Sun Apr 06, 2008 4:49 pm Post subject: Facet Fuel pump amperage

Jeff



 I believe that the only important thing about amperage of the pumps is that you size the wires appropriately so that the wires are sized large enough so that:



 1. they don't overheat, and

 2. the voltage remaining after the drop in the wire is sufficient to drive the pump.



 The function of the fuse is to protect the wire, not the pump. You do not want the wire to overheat and start a fire.



 So I suggest you go with a fuse of the largest amperage that will not severely overheat the wires. Check out Table 11-3 in AC43.13-1B. If you're using AWG 22 wire, use a 5 amp fuse.



 Terry



 



 At 07:51 PM 4/6/2008 -0400, you wrote:



  	  Quote: 	
		  I'm using the Facet 40105 fuel pumps in my leading edge fuel tanks only fuel system.  I wired up the pumps today and tested them for the first time.  According to Facet/ Purolator, they should draw .75 to 1 amp.  With 1 amp fuses on each both pumps promptly blew the fuses on their separate circuits after a few seconds.  I put in 2 amp fuses and both would run OK.  Looking at the archives, there was a lot of discussion about this in the 1999 and 2000 time frame.  Since the documentation seems to be inaccurate, what size fuse or breaker are those with this pump using: one, two, three, or five amp fuses?  Thanks ….

 

  

 

 Jeff Davidson

 

 CH601-HD/Jabiru 3300A

 

 Gonna' finish sometime! 	
 

 

 Terry Phillips

 ttp44~at~rkymtn.net

 Corvallis MT

 601XL/Jab 3300 s .. l .. o .. o .. w build kit - Tail, flaps, & ailerons are done; working on the wings

 http://www.mykitlog.com/N47TP/     [quote][b]

_________________
Terry Phillips
Corvallis, MT
ttp44<at>rkymtn.net
Zenith 601XL/Jab 3300 slow build kit - Tail feathers done; working on the wings.

jeffrey_davidson(at)earth
Guest

Posted: Sun Apr 06, 2008 5:36 pm Post subject: Facet Fuel pump amperage

Do not archive  

Thanks Terry.  My wires are fine. I was thinking about that 30 amp fuse that protects the entire electrical system.  Blowing that could turn a lot of things off!  I figured 1 amp for each fuel pump when I calculated my electrical load.  The Jabiru has a 20 amp generator.  

Jeff Davidson  

   

         

  

From: owner-zenith-list-server(at)matronics.com [mailto:owner-zenith-list-server(at)matronics.com] On Behalf Of Terry Phillips

 Sent: Sunday, April 06, 2008 8:43 PM

 To: zenith-list(at)matronics.com

 Subject: Re: Facet Fuel pump amperage   

  

   

Jeff

 

 I believe that the only important thing about amperage of the pumps is that you size the wires appropriately so that the wires are sized large enough so that:

 

 1. they don't overheat, and

 2. the voltage remaining after the drop in the wire is sufficient to drive the pump.

 

 The function of the fuse is to protect the wire, not the pump. You do not want the wire to overheat and start a fire.

 

 So I suggest you go with a fuse of the largest amperage that will not severely overheat the wires. Check out Table 11-3 in AC43.13-1B. If you're using AWG 22 wire, use a 5 amp fuse.

 

 Terry

 

 

 

 At 07:51 PM 4/6/2008 -0400, you wrote:

 

 

   

I'm using the Facet 40105 fuel pumps in my leading edge fuel tanks only fuel system.  I wired up the pumps today and tested them for the first time.  According to Facet/ Purolator, they should draw .75 to 1 amp.  With 1 amp fuses on each both pumps promptly blew the fuses on their separate circuits after a few seconds.  I put in 2 amp fuses and both would run OK.  Looking at the archives, there was a lot of discussion about this in the 1999 and 2000 time frame.  Since the documentation seems to be inaccurate, what size fuse or breaker are those with this pump using: one, two, three, or five amp fuses?  Thanks ….

 

  

 

 Jeff Davidson

 

 CH601-HD/Jabiru 3300A

 

 Gonna' finish sometime!  



 Terry Phillips

 ttp44~at~rkymtn.net

 Corvallis MT

 601XL/Jab 3300 s .. l .. o .. o .. w build kit - Tail, flaps, & ailerons are done; working on the wings

 http://www.mykitlog.com/N47TP/    	  Quote: 	
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psm(at)ATT.NET
Guest

Posted: Sun Apr 06, 2008 6:15 pm Post subject: Facet Fuel pump amperage

Hi Jeff,



 I would go with the bigger fuse and not worry about it.  If the fuel pump develops a short to ground then any size fuse will blow.



 Paul

 XL fuselage



 

 At 04:51 PM 4/6/2008, you wrote:



 [quote]I'm using the Facet 40105 fuel pumps in my leading edge fuel tanks only fuel system.  I wired up the pumps today and tested them for the first time.  According to Facet/ Purolator, they should draw .75 to 1 amp.  With 1 amp fuses on each both pumps promptly blew the fuses on their separate circuits after a few seconds.  I put in 2 amp fuses and both would run OK.  Looking at the archives, there was a lot of discussion about this in the 1999 and 2000 time frame.  Since the documentation seems to be inaccurate, what size fuse or breaker are those with this pump using: one, two, three, or five amp fuses?  Thanks ….

 

  

 

 Jeff Davidson

 

 CH601-HD/Jabiru 3300A

 

 Gonna' finish sometime[b]

Terry Phillips

Joined: 11 Jan 2006
Posts: 346
Location: Corvallis, MT

Posted: Sun Apr 06, 2008 7:13 pm Post subject: Facet Fuel pump amperage

Interesting approach, Jeff. 



 If I understand you correctly, you are concerned that a momentary, short circuit load on, e.g., a fuel pump power lead might blow your main system fuse.



 I'm just a reader of the aeroelectric connection, and most of what I know about airplane electric systems comes from there. And, God knows, I don't understand all that I've read. So, take this with that in mind.  



 I haven't seen your schematic, so I'm not sure what the function is of the 30 amp fuse that "protects the entire electric system." I know that the Jabiru 3300 alternator is rated at 20 amps. That says to me that the steady state load on the electrical system should be less than 20 amps (so there are some amps left over to recharge the battery after starting). A transient load can be much greater than 20 without compromising the system--what does your  starter draw? More than 30 amps, I'd guess. 



 So, if the 30 amp fuse is designed to protect the cable from the battery to the main bus, you might consider a larger cable. Then you don't have to worry about blowing the 30 amp fuse. If you're happy with 30-amp capacity, you might consider using some sort of slow-blow 30-amp fuse so that a momentary 5 amp overload on some circuit would not blow the main fuse. (Something like the LITTELFUSE JCASE HIGH AMP FUSE, PINK 30 AMP (JCAS30BP)) 



 The fuse-to-protect-the-wiring approach makes sense to me. Other approaches might work for you. But I think that the last thing I'd want in my airplane is a fuse to the fuel pump that is operating right at the limit of its capacity.



 Terry



 

 At 09:33 PM 4/6/2008 -0400, you wrote:



  	  Quote: 	
		  Do not archive

 

 Thanks Terry.  My wires are fine. I was thinking about that 30 amp fuse that protects the entire electrical system.  Blowing that could turn a lot of things off!  I figured 1 amp for each fuel pump when I calculated my electrical load.  The Jabiru has a 20 amp generator.

 

 Jeff Davidson

 

  

 

  

  

 From: owner-zenith-list-server(at)matronics.com [mailto:owner-zenith-list-server(at)matronics.com (owner-zenith-list-server(at)matronics.com)] On Behalf Of Terry Phillips

 Sent: Sunday, April 06, 2008 8:43 PM

 To: zenith-list(at)matronics.com

 Subject: Re: Facet Fuel pump amperage 

 

  

 

 Jeff



 I believe that the only important thing about amperage of the pumps is that you size the wires appropriately so that the wires are sized large enough so that:



 1. they don't overheat, and

 2. the voltage remaining after the drop in the wire is sufficient to drive the pump.



 The function of the fuse is to protect the wire, not the pump. You do not want the wire to overheat and start a fire.



 So I suggest you go with a fuse of the largest amperage that will not severely overheat the wires. Check out Table 11-3 in AC43.13-1B. If you're using AWG 22 wire, use a 5 amp fuse.



 Terry



 



 At 07:51 PM 4/6/2008 -0400, you wrote:



 

 I'm using the Facet 40105 fuel pumps in my leading edge fuel tanks only fuel system.  I wired up the pumps today and tested them for the first time.  According to Facet/ Purolator, they should draw .75 to 1 amp.  With 1 amp fuses on each both pumps promptly blew the fuses on their separate circuits after a few seconds.  I put in 2 amp fuses and both would run OK.  Looking at the archives, there was a lot of discussion about this in the 1999 and 2000 time frame.  Since the documentation seems to be inaccurate, what size fuse or breaker are those with this pump using: one, two, three, or five amp fuses?  Thanks &.

 

  

 

 Jeff Davidson

 

 CH601-HD/Jabiru 3300A

 

 Gonna' finish sometime!

 

 

 Terry Phillips

 ttp44~at~rkymtn.net

 Corvallis MT

 601XL/Jab 3300 s .. l .. o .. o .. w build kit - Tail, flaps, & ailerons are done; working on the wings

 http://www.mykitlog.com/N47TP/ 

 

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		  http://www.matronics.com/contribution[/b] 	


 

 

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 Terry Phillips

 ttp44~at~rkymtn.net

 Corvallis MT

 601XL/Jab 3300 s .. l .. o .. o .. w build kit - Tail, flaps, & ailerons are done; working on the wings

 http://www.mykitlog.com/N47TP/     [quote][b]

_________________
Terry Phillips
Corvallis, MT
ttp44<at>rkymtn.net
Zenith 601XL/Jab 3300 slow build kit - Tail feathers done; working on the wings.

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Sun Apr 06, 2008 7:33 pm Post subject: Facet Fuel pump amperage

I have 5 amp fuses for my facet pumps. As a general rule, the fuse should be rated for at least 125% of the maximum continuous load on the circuit. The primary function of the fuse is to protect the wire feeding the circuit, not to protect the device being fed by the circuit. It doesn't hurt to have a larger fuse than the device is rated for, as long as the wire feeding the circuit can handle it. 

On Apr 6, 2008, at 7:51 PM, Jeff wrote: 	  Quote: 	
		  I'm using the Facet 40105 fuel pumps in my leading edge fuel tanks only fuel system.  I wired up the pumps today and tested them for the first time.  According to Facet/ Purolator, they should draw .75 to 1 amp.  With 1 amp fuses on each both pumps promptly blew the fuses on their separate circuits after a few seconds.  I put in 2 amp fuses and both would run OK.  Looking at the archives, there was a lot of discussion about this in the 1999 and 2000 time frame.  Since the documentation seems to be inaccurate, what size fuse or breaker are those with this pump using: one, two, three, or five amp fuses?  Thanks ….

 

Jeff Davidson

CH601-HD/Jabiru 3300A

Gonna' finish sometime!





	




 -- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.



 



 [quote][b]

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

craig(at)craigandjean.com
Guest

Posted: Sun Apr 06, 2008 7:45 pm Post subject: Facet Fuel pump amperage

This link says “Apply pump to a properly fused circuit of 3-7 amps.”:  

   

http://www.facet-purolator.com/mcl/pages/frame_src/ttips_frmsrc.html  

   

This page says “1.6 amp average”:  

   

http://www.facet-purolator.com/mcl/media/technology/hd_pdfs/Cubed_Solid.pdf  

   

-- Craig  

       

From: owner-zenith-list-server(at)matronics.com [mailto:owner-zenith-list-server(at)matronics.com] On Behalf Of Jeff 

 Sent: Sunday, April 06, 2008 5:51 PM

 To: zenith-list(at)matronics.com

 Subject: Facet Fuel pump amperage   

  

  

   

I'm using the Facet 40105 fuel pumps in my leading edge fuel tanks only fuel system.  I wired up the pumps today and tested them for the first time.  According to Facet/ Purolator, they should draw .75 to 1 amp.  With 1 amp fuses on each both pumps promptly blew the fuses on their separate circuits after a few seconds.  I put in 2 amp fuses and both would run OK.  Looking at the archives, there was a lot of discussion about this in the 1999 and 2000 time frame.  Since the documentation seems to be inaccurate, what size fuse or breaker are those with this pump using: one, two, three, or five amp fuses?  Thanks ….  

   

Jeff Davidson  

CH601-HD/Jabiru 3300A  

Gonna' finish sometime!  

   

    	  Quote: 	
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larry(at)macsmachine.com
Guest

Posted: Mon Apr 07, 2008 6:04 am Post subject: Facet Fuel pump amperage

Hi Jeff,

I've got 40105 pumps in my wings and two on the firewall. Seldom have 

more than two going at any time, but I have a 7.5 amp fuse to operate 

all four. I've never blown

a pump fuse. They probably only draw an amp, but a little more fuse here 

will not harm anything.



Larry McFarland 601HDS at www.macsmachine.com



Jeff wrote:

 	  Quote: 	
		  

 I'm using the Facet 40105 fuel pumps in my leading edge fuel tanks 

 only fuel system. I wired up the pumps today and tested them for the 

 first time. According to Facet/ Purolator, they should draw .75 to 1 

 amp. With 1 amp fuses on each both pumps promptly blew the fuses on 

 their separate circuits after a few seconds. I put in 2 amp fuses and 

 both would run OK. Looking at the archives, there was a lot of 

 discussion about this in the 1999 and 2000 time frame. Since the 

 documentation seems to be inaccurate, what size fuse or breaker are 

 those with this pump using: one, two, three, or five amp fuses? Thanks ….



 Jeff Davidson



 CH601-HD/Jabiru 3300A



 Gonna' finish sometime!

Gig Giacona

Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA

Posted: Mon Apr 07, 2008 6:13 am Post subject: Re: Facet Fuel pump amperage

I'm just getting into the electrical stuff on my plane. So please tell me if my thinking is off here.



This seems like a place for multiple fuses if there ever was one. If you blow a fuse you loose all 4 where the problem might just be on one pump. 



 	  larry(at)macsmachine.com wrote: 	
		  Hi Jeff,

I've got 40105 pumps in my wings and two on the firewall. Seldom have 

more than two going at any time, but I have a 7.5 amp fuse to operate 

all four. I've never blown

a pump fuse. They probably only draw an amp, but a little more fuse here 

will not harm anything.



Larry McFarland 601HDS at www.macsmachine.com

_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR

dougsnash(at)yahoo.com
Guest

Posted: Mon Apr 07, 2008 6:28 am Post subject: Facet Fuel pump amperage

Jeff, remember that the fuse/breaker is there to

protect the wiring not the load.  Size you breaker

according to the size of wire.  I forget the exact

numbers but 18 ga wire is supposed to be able to

support something like a total of 10A.



Doug MacDonald

CH-701 Scratch builder

NW Ontario, Canada



Do not Archive

--- Jeff  <jeffrey_davidson(at)earthlink.net> wrote:



 	  Quote: 	
		   I'm using the Facet 40105 fuel pumps in my leading

 edge fuel tanks only fuel

 system.  I wired up the pumps today and tested them

 for the first time.

 According to Facet/ Purolator, they should draw .75

 to 1 amp.  With 1 amp

 fuses on each both pumps promptly blew the fuses on

 their separate circuits

 after a few seconds.  I put in 2 amp fuses and both

 would run OK.  Looking

 at the archives, there was a lot of discussion about

 this in the 1999 and

 2000 time frame.  Since the documentation seems to

 be inaccurate, what size

 fuse or breaker are those with this pump using: one,

 two, three, or five amp

 fuses?  Thanks ..


	


You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost.  

http://tc.deals.yahoo.com/tc/blockbuster/text5.com

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Mon Apr 07, 2008 8:19 am Post subject: Facet Fuel pump amperage

I have my fuel pumps wired to my ignition circuit (I don't have 

magnetos). My ignition switch is fed directly from the battery through a 

30 Amp fuse, bypassing the master switch. The ignition switch feeds a 

coil selector switch, a pump selector switch and the engine instruments. 

Each pump and each ignition coil is then fed from its selector switch 

through its own 5 Amp breaker. If a breaker pops, I switch to the 

backup. I don't have an engine driven pump so the electric pumps are 

essential. My "run-up" consists of checking that the both pumps and both 

coils will function.

If I have to shut down the electrical system in flight for any reason, 

the engine can continue to operate after the master is shut down for as 

long as the battery holds up. It's true that if one of the three 

switches fail, the engine will probably quit, but switches don't 

generally fail unless they are being switched and I don't normally 

switch any of these in flight. This was a relatively simple way of 

getting some redundancy in the system. If the 30 Amp fuse blows, well, 

then it's time to land.

Gig Giacona wrote:

 	  Quote: 	

 I'm just getting into the electrical stuff on my plane. So please tell me if my thinking is off here.

 This seems like a place for multiple fuses if there ever was one. If you blow a fuse you loose all 4 where the problem might just be on one pump. 

 larry(at)macsmachine.com wrote:

> Hi Jeff,

> I've got 40105 pumps in my wings and two on the firewall. Seldom have 

> more than two going at any time, but I have a 7.5 amp fuse to operate 

> all four. I've never blown

> a pump fuse. They probably only draw an amp, but a little more fuse here 

> will not harm anything.

>

> Larry McFarland 601HDS at www.macsmachine.com

>

-- 

Bryan Martin

Zenith 601XL N61BM

Ram Subaru, Stratus redrive

Do Not Archive

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

larry(at)macsmachine.com
Guest

Posted: Mon Apr 07, 2008 8:23 am Post subject: Facet Fuel pump amperage

You're right of course, Gig,

I checked my fuse diagram and the 2 boost pumps are on one 7.5 fuse and 

the wings pumps are on another

7.5 fuse.



Larry McFarland 601HDS at www.macsmachine.com

do not archive

Gig Giacona wrote:

 	  Quote: 	
		   



 I'm just getting into the electrical stuff on my plane. So please tell me if my thinking is off here.



 This seems like a place for multiple fuses if there ever was one. If you blow a fuse you loose all 4 where the problem might just be on one pump. 





 larry(at)macsmachine.com wrote:

   

> Hi Jeff,

> I've got 40105 pumps in my wings and two on the firewall. Seldom have 

> more than two going at any time, but I have a 7.5 amp fuse to operate 

> all four. I've never blown

> a pump fuse. They probably only draw an amp, but a little more fuse here 

> will not harm anything.

>

> Larry McFarland 601HDS at www.macsmachine.com

>

>     

 --------

 W.R. &quot;Gig&quot; Giacona

 601XL Under Construction

 See my progress at www.peoamerica.net/N601WR





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=175246#175246

psm(at)att.net
Guest

Posted: Mon Apr 07, 2008 8:24 am Post subject: Facet Fuel pump amperage

Hi Gig,



I guess you could go either way.  I would expect things to go without 

blowing a fuse on fuel pumps for a very long time.  If it does blow 

and you can't replace the fuse in flight that just means you must 

depend on the mechanical fuel pump on your engine for the remainder 

of that flight.



If you have a plane that depends on a working electric fuel pump to 

keep the engine going then perhaps separate fuses would be in order.



Paul

XL fuselage

do not archive

At 07:13 AM 4/7/2008, you wrote:

 	  Quote: 	
		  I'm just getting into the electrical stuff on my plane. So please 

tell me if my thinking is off here.



This seems like a place for multiple fuses if there ever was one. If 

you blow a fuse you loose all 4 where the problem might just be on one pump.

Flydog1966(at)aol.com
Guest

Posted: Mon Apr 07, 2008 9:42 am Post subject: Facet Fuel pump amperage

In a message dated 4/7/2008 10:29:52 A.M. Eastern Daylight Time,  dougsnash(at)yahoo.com writes:

  	  Quote: 	
		  Jeff,    remember that the fuse/breaker is there to

protect the wiring not the    load.  Size you breaker

according to the size of wire.   	


 

 Makes sense to me, but, any harm in also having a fuse at the  pump( or any electronic device) to protect it ?

   Kinda like the circuit breaker in the house is there to protect the  wiring, but many of the gizmos that plug in

 at the other end have fuses in them to protect the gizmo.

 Phil

 please do not archive



Planning your summer road trip? Check out AOL Travel Guides.

  [quote][b]

daveaustin2(at)primus.ca
Guest

Posted: Mon Apr 07, 2008 9:47 am Post subject: Facet Fuel pump amperage

As an old electrical engineer, there is a rule of thumb that says you should 

fuse at three times the normal circuit load.  That pretty well ensures that 

the fuse will not blow under normal (and start-up) load but will if a short 

develops in the circuit.  I agree that there should be a separate fuse for 

each pump.

Dave Austin  601HDS - 912, Spitfire Mk VIII

dougsnash(at)yahoo.com
Guest

Posted: Mon Apr 07, 2008 1:49 pm Post subject: Facet Fuel pump amperage

Actually Phil, the extra fuse at the pump is not

really needed.  The purpose of the internal fuse in

your houshold appliance is to prevent it from catching

fire if it melts down.  Remember, the 15A breaker on

your house panel is sized for the 14/2  cable in your

walls and the internal fuse is sized for the 22ga

wiring inside your TV, etc.  Not likely an issue with

the plane.  It is a common misconception that fuses

are to protect "gizmos"  The are not.  They are there

to disconnect the power when the "gizmo" melt down.



Of a bigger concern might be putting each of the pumps

on a different circuit.  Then if you were to loose one

pump due to a chafed wire or someting, you would still

be able to run the other.  Designing low wing fuel

systems however, is beyond my expirience as I have

gravity feeding mine.



Doug MacDonald

CH-701 Scratch Builder

NW Ontario, Canada



Do Not Archive



--- Flydog1966(at)aol.com wrote:



 	  Quote: 	
		    

 In a message dated 4/7/2008 10:29:52 A.M. Eastern

 Daylight Time,  

 dougsnash(at)yahoo.com writes:

 

 Jeff,  remember that the fuse/breaker is there to

 protect the wiring not the  load.  Size you breaker

 according to the size of wire.  

 

 

 Makes sense to me, but, any harm in also having a

 fuse at the  pump( or any 

 electronic device) to protect it ?

   Kinda like the circuit breaker in the house is

 there to protect the  

 wiring, but many of the gizmos that plug in

 at the other end have fuses in them to protect the

 gizmo.

 Phil

 please do not archive

 


	


You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost.  

http://tc.deals.yahoo.com/tc/blockbuster/text5.com

jeffrey_davidson(at)earth
Guest

Posted: Mon Apr 07, 2008 4:47 pm Post subject: Facet Fuel pump amperage

Terry,  

   

            I overstated the importance of the 30 AMP fuse.  It is located between the battery contractor and the main fuse block.  The 30 AMP fuse is not in the path from the battery to the starter.  The starter pulls an amazing amount of amperage, but only for a few seconds in most cases!  But that fuse does protect everything that draws its power from the main fuse block including the avionics fuse block.  This design is stolen from flying 601s with 3300s up front and is, or used to be, recommended by Jabiru USA.  The Jabiru 3300 installation manual includes a suggested wiring diagram that includes the 30 Amp fuse on Page 10.  My electrical system is a combination of Jabiru instructions and AeroElectric advice tempered with real life experience from some other very helpful builders and some of my own "common sense".  Of course Jabiru never imagined a fuel system like mine in any of their aircraft.  Anyway, thanks for the comments.   I'm Okay with a larger amperage fuse now that I find 5 AMP fuses are common for each fuel pump circuit.  That is what I wanted.  It seems to me that there is more involved than just the fact that the fuses are there to protect the wires.  The maximum electrical load is pretty important too.  Evidently is common to have fuses that blow at about three times the expected normal load for each circuit.  That is what I didn't know.  

   

            Thanks to everyone that responded to my question.  

   

            Time to go pick out a fabric for my seat cushions!  

              

            Jeff Davidson  

   

         

  

From: owner-zenith-list-server(at)matronics.com [mailto:owner-zenith-list-server(at)matronics.com] On Behalf Of Terry Phillips

 Sent: Sunday, April 06, 2008 11:07 PM

 To: zenith-list(at)matronics.com

 Subject: RE: Facet Fuel pump amperage   

  

   

Interesting approach, Jeff. 

 

 If I understand you correctly, you are concerned that a momentary, short circuit load on, e.g., a fuel pump power lead might blow your main system fuse.

 

 I'm just a reader of the aeroelectric connection, and most of what I know about airplane electric systems comes from there. And, God knows, I don't understand all that I've read. So, take this with that in mind. 

 

 I haven't seen your schematic, so I'm not sure what the function is of the 30 amp fuse that "protects the entire electric system." I know that the Jabiru 3300 alternator is rated at 20 amps. That says to me that the steady state load on the electrical system should be less than 20 amps (so there are some amps left over to recharge the battery after starting). A transient load can be much greater than 20 without compromising the system--what does your  starter draw? More than 30 amps, I'd guess. 

 

 So, if the 30 amp fuse is designed to protect the cable from the battery to the main bus, you might consider a larger cable. Then you don't have to worry about blowing the 30 amp fuse. If you're happy with 30-amp capacity, you might consider using some sort of slow-blow 30-amp fuse so that a momentary 5 amp overload on some circuit would not blow the main fuse. (Something like the LITTELFUSE JCASE HIGH AMP FUSE, PINK 30 AMP (JCAS30BP)) 

 

 The fuse-to-protect-the-wiring approach makes sense to me. Other approaches might work for you. But I think that the last thing I'd want in my airplane is a fuse to the fuel pump that is operating right at the limit of its capacity.

 

 Terry

 

 

   

       [quote][b]

Terry Phillips

Joined: 11 Jan 2006
Posts: 346
Location: Corvallis, MT

Posted: Mon Apr 07, 2008 6:47 pm Post subject: Facet Fuel pump amperage

Jeff



 As I'm always telling my wife, sounds like it will all work out OK. In case you haven't seen it, you might take a look at Nuckolls' schematic Z21A which says it's for a Jabiru 3300 with EFCI. I don't know where the EFCI came from, but I'm planning on adapting Z21A--when I get that far. It wasn't in my copy of Aeroelectric Connection, but I got it off Bob's website. I had a hard time finding it, so I'll post the link, in case anyone is interested.



 http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z21A.pdf



 Terry



 



 

 At 08:44 PM 4/7/2008 -0400, you wrote:



  	  Quote: 	
		  Terry,

 

  

 

             I overstated the importance of the 30 AMP fuse.  It is located between the battery contractor and the main fuse block.  The 30 AMP fuse is not in the path from the battery to the starter.  The starter pulls an amazing amount of amperage, but only for a few seconds in most cases!  But that fuse does protect everything that draws its power from the main fuse block including the avionics fuse block.  This design is stolen from flying 601s with 3300s up front and is, or used to be, recommended by Jabiru USA.  The Jabiru 3300 installation manual includes a suggested wiring diagram that includes the 30 Amp fuse on Page 10.  My electrical system is a combination of Jabiru instructions and AeroElectric advice tempered with real life experience from some other very helpful builders and some of my own "common sense".  Of course Jabiru never imagined a fuel system like mine in any of their aircraft.  Anyway, thanks for the comments.   I'm Okay with a larger amperage fuse now that I find 5 AMP fuses are common for each fuel pump circuit.  That is what I wanted.  It seems to me that there is more involved than just the fact that the fuses are there to protect the wires.  The maximum electrical load is pretty important too.  Evidently is common to have fuses that blow at about three times the expected normal load for each circuit.  That is what I didn't know.

 

  

 

             Thanks to everyone that responded to my question.

 

  

 

             Time to go pick out a fabric for my seat cushions!

 

             

 

             Jeff Davidson 	
 

 

 Terry Phillips

 ttp44~at~rkymtn.net

 Corvallis MT

 601XL/Jab 3300 s .. l .. o .. o .. w build kit - Tail, flaps, & ailerons are done; working on the wings

 http://www.mykitlog.com/N47TP/     [quote][b]

_________________
Terry Phillips
Corvallis, MT
ttp44<at>rkymtn.net
Zenith 601XL/Jab 3300 slow build kit - Tail feathers done; working on the wings.

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