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Running Big Battery Wire Through Firewall

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DaveG601XL

Joined: 27 Oct 2006
Posts: 351
Location: Cincinnati, Oh

Posted: Wed Mar 10, 2010 6:06 am Post subject: Running Big Battery Wire Through Firewall

I have a friend who is building a metal airplane where the battery will be mounted in the tail with a big 2GA positive wire going through the firewall.  I did not run into this on my airplane so I am asking what is the best way to lead this wire through the firewall.  Do you run a continuous wire with a grand-daddy grommet or use a bolted stud on either side?  We can figure the fire protection part out seperately after we find out which way is best for routing the electrical path. 



Thanks,

_________________
David Gallagher
Cincinnati, OH area

corey.crawford(at)gmail.c
Guest

Posted: Wed Mar 10, 2010 7:04 am Post subject: Running Big Battery Wire Through Firewall

I'm not sure if this is exactly what you are asking about, but this is the

product I'm using for my firewall power pass-through.



Feed-through Terminal<http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/144078/377%20710%201635/0/High%20Amp%20Distribution/Primary%20Search/mode%20matchallpartial/0/0?N=377%20710%201635&Ne=0&Ntt=High%20Amp%20Distribution&Ntx=mode%20matchallpartial&page=CategoryDisplayLevel1&isLTokenURL=true&storeNum=5002&subdeptNum=9&classNum=119#>



--

Corey Crawford

corey.crawford(at)gmail.com



On Wed, Mar 10, 2010 at 7:06 AM, DaveG601XL <david.m.gallagher(at)ge.com>

wrote:

 	  Quote: 	
		   

david.m.gallagher(at)ge.com>
	


 	  Quote: 	
		  

 I have a friend who is building a metal airplane where the battery will be

mounted in the tail with a big 2GA positive wire going through the firewall

jaybannist(at)cs.com
Guest

Posted: Wed Mar 10, 2010 7:04 am Post subject: Running Big Battery Wire Through Firewall

Dave,

 

 I used a Moroso thru panel battery connector, P/N 74145.  I think I got it from Summit Racing on line.

 

 Jay Bannister

 

   

 

  

   

 

   

 

  --

longg(at)pjm.com
Guest

Posted: Wed Mar 10, 2010 7:04 am Post subject: Running Big Battery Wire Through Firewall

David,



I can tell you there is more than one way to skin a cat, but if you look

at one of the gazillion Piper Cherokees out there, the cable runs from

under the back seat along the left panel through the generally dry

rotted grand-daddy grommet to the contactor mounted on the firewall.

Size does matter but for 2 or 4 GA that won't make a difference. Good

enough for Piper...



Glenn



--

Allen Fulmer

Joined: 10 Jan 2006
Posts: 79
Location: Alexander City, AL

Posted: Wed Mar 10, 2010 7:50 pm Post subject: Running Big Battery Wire Through Firewall

I used stud pass through I purchased from West Marine online.



Allen Fulmer

RV7 Finish wiring

_________________
RV7 QB Fuselage
Eggenfellner H6 on orde
N808AF reserved
Alexander City, AL

aerobubba(at)earthlink.ne
Guest

Posted: Thu Mar 11, 2010 4:37 am Post subject: Running Big Battery Wire Through Firewall

Hi Dave-



I used Bob's shower bar arrangement, and am quite happy with the result.  I

actually ended up with two penetrations, one aircraft left that carries the

engine control cables and higher power electrical lines, and one aircraft

right that carries sensor lines.



glen matejcek

aerobubba(at)earthlink.net



 	  Quote: 	
		   Time: 06:08:23 AM PST US

 Subject: Running Big Battery Wire Through Firewall

 From: "DaveG601XL" <david.m.gallagher(at)ge.com>

 I have a friend who is building a metal airplane where the battery will

be mounted
	


 	  Quote: 	
		   in the tail with a big 2GA positive wire going through the firewall.  I

did
	


 	  Quote: 	
		   not run into this on my airplane so I am asking what is the best way to

lead
	


 	  Quote: 	
		   this wire through the firewall.  Do you run a continuous wire with a

grand-daddy
	


 	  Quote: 	
		   grommet or use a bolted stud on either side?  We can figure the fire

protection
	


 	  Quote: 	
		   part out seperately after we find out which way is best for routing the

 electrical path. 



 Thanks,



 --------

 David Gallagher

 601 XL/Jabiru 3300

 First flight 7/24/08

 116.5 hours and holding (incorporating upgrade)

longg(at)pjm.com
Guest

Posted: Thu Mar 11, 2010 8:50 am Post subject: Running Big Battery Wire Through Firewall

Dave,



Lancairs often use Industrial Cable Grips for pass through items. They

look good, are leak proof and do a great job of protecting the wire(s).

Much better than a grommet and very easy to install.



I too like the stud bolts ala West Marine but find that also creates

addition exposed connections for stuff to rub against.



Glenn



 	  Quote: 	
		   Time: 06:08:23 AM PST US

 Subject: Running Big Battery Wire Through Firewall

 From: "DaveG601XL" <david.m.gallagher(at)ge.com>

 I have a friend who is building a metal airplane where the battery

will
	


be mounted

 	  Quote: 	
		   in the tail with a big 2GA positive wire going through the firewall.

I
	


did

 	  Quote: 	
		   not run into this on my airplane so I am asking what is the best way

to
	


lead

 	  Quote: 	
		   this wire through the firewall.  Do you run a continuous wire with a

grand-daddy
	


 	  Quote: 	
		   grommet or use a bolted stud on either side?  We can figure the fire

protection
	


 	  Quote: 	
		   part out seperately after we find out which way is best for routing

the
	


 	  Quote: 	
		   electrical path. 



 Thanks,



 --------

 David Gallagher

 601 XL/Jabiru 3300

 First flight 7/24/08

 116.5 hours and holding (incorporating upgrade)

DaveG601XL

Joined: 27 Oct 2006
Posts: 351
Location: Cincinnati, Oh

Posted: Thu Mar 11, 2010 12:02 pm Post subject: Re: Running Big Battery Wire Through Firewall

Thanks for the input.  I think we have decided on the single wire through a flange & tube arrangement with RTV protection.  I guess that is what was referenced as the "shower bar" approach.  First time I heard it called that, but I guess it fits.



Great to have a discussion board such as this!

_________________
David Gallagher
Cincinnati, OH area

sarg314(at)gmail.com
Guest

Posted: Thu Mar 11, 2010 1:06 pm Post subject: Running Big Battery Wire Through Firewall

David:

Actually it's the end cut off a toilet grab bar.Â  It's stainless steel and - very important - it turns a 90 degree angle.Â  It's a 90 deg elbow on a flange.Â  I have always thought, though I can't prove it, that the 90 deg. bend adds substantially to the fire-barrier qualities of the tube.Â  It's fairly thin wall tube, but the flange is pretty thick, so the only downside is it's kind of heavy.Â  One made specifically for this purpose would probably have half the weight.

 

On Thu, Mar 11, 2010 at 1:02 PM, DaveG601XL <david.m.gallagher(at)ge.com (david.m.gallagher(at)ge.com)> wrote:

 	  Quote: 	
		   --> AeroElectric-List message posted by: "DaveG601XL" <david.m.gallagher(at)ge.com (david.m.gallagher(at)ge.com)>

 

 Thanks for the input. Â I think we have decided on the single wire through a flange & tube arrangement with RTV protection. Â I guess that is what was referenced as the "shower bar" approach. Â First time I heard it called that, but I guess it fits.

  

 Great to have a discussion board such as this!

 

 	


-- 

Tom Sargent

  [quote][b]

aerobubba(at)earthlink.ne
Guest

Posted: Fri Mar 12, 2010 7:03 am Post subject: Running Big Battery Wire Through Firewall

HI David-



To expand on this topic a bit, the preferred sealant is an intumescent fire

block, not RTV.  You can get it in the aviation department of Lowe's et al.

I believe Bob has a tutorial on his website that covers all the detail.  



All my sensor lines, including MP, pass thru these fittings.



glen matejcek

aerobubba(at)earthlink.ne

longg(at)pjm.com
Guest

Posted: Fri Mar 12, 2010 7:55 am Post subject: Running Big Battery Wire Through Firewall

Correct, also available at Ace and other fine Aero-motive department

stores. Cost is about $10/tube. After that you can install the remote

halon tubing and tips to put out the fire once it really gets going.

That will set ya back $500-$600 for the push type with a 5 lb tank.



http://www.acehardware.com/family/index.jsp?categoryId=2624911



Glenn



--

corey.crawford(at)gmail.c
Guest

Posted: Thu Mar 18, 2010 9:10 pm Post subject: Running Big Battery Wire Through Firewall

Because I was curious, I emailed Blue Sea Systems to get information on the flammability properties of their Bulkhead Electrical Pass-through unit (found here: http://bluesea.com/products/2201). For those also curious, this is the information I received back:

  

PN: 2201 is molded in Zytel FR50 NC010, which has a UL94 V0 flammability rating. I'm pretty certain the Zytel FR50 is an SAE approved under the hood material though. Almost all electrical connector housings (Molex, FCi, Deutsch, etc.) are molded in glass reinforced Nylon 6 6.

  

If you didn’t already know, UL94 is the Underwriters Laboratory test standard for plastics flammability. V0 is the best you can do. There are constraints or design guidelines for different thicknesses of materials though. A 1/16" thick section of a material will likely burn more readily than one  1/8" thick, and each material tested comes with a rating at a thickness, but they're not all the same. In our product's case, design thickness has been handily exceeded.

  

Another gauge for plastics materials underhood is elevated temp properties. The heat deflection temperature(HDT) is actually quite high for Nylon 6 6 - especially when glass filled as ours is. One excellent feature of a VO thermoplastics materials is that it can still be tough. Phenolics (think Bakelite) have the best high temperature performance, but can be very brittle.

  

Having written all of that, I must confess PN: 2201 predates my tenure here at Blue Sea. I personally have not flame tested it, though I understand the guy who's chair I took was fond of such activities. I can say from years of experience that PN: 2201 has some good features to help keep it from melting or burning besides the plastics material. For one thing there is a large (relative to molded component) brass heat sink in the thru-conductor that is insert molded within.

  

Provided you don’t plan on using it for welding for extended periods, and that you size wires appropriate for your application(s), there are probably very few if any better products on the market.



Interesting stuff. I come from computer software, so all this materials science is something new to learn.

  --

Corey Crawford

corey.crawford(at)gmail.com (corey.crawford(at)gmail.com)

 



On Tue, Mar 16, 2010 at 11:48 AM,  <robert.mccallum2(at)sympatico.ca (robert.mccallum2(at)sympatico.ca)> wrote:

[quote]       The plastic from which they're made, (at least most of them) melts, then burns leaving you with flames on the "wrong" side of the firewall and an open hole admitting more smoke and flames. Also you now have a bare, uninsulated, live heavy wire, (stud) arcing like crazy against the firewall sheetmetal. Doesn't seem like a "safe" penetration to me. The intumescent caulk idea swells up with heat keeping the hole sealed and insulating the interior from flames and smoke and preventing the wires, even if they themselves are compromised, from shorting to the firewall.

    

 Bob McC 



[b]

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