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nuckolls.bob(at)aeroelect
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 Posted: Mon Mar 15, 2010 10:31 am Post subject: Running Big Battery Wire Through Firewall |
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At 08:37 AM 3/10/2010, you wrote:
| Quote: | --> AeroElectric-List message posted by: <longg(at)pjm.com>
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... |
I don't think I've yet seen a commercial-off-the-shelf firewall
feedthru where the insulating material would have stood off
Jack Thermin's "puff the magic dragon" test. Electrically
and mechanically, these critters function as advertised.
The price is low and they seem adequately robust.
However, if one subscribes to the notion of protecting
firewall integrity with processes like . . .
http://www.aeroelectric.com/articles/Firewall_Penetration/firewall.html
then devices like . . .
[img]cid:.0[/img]
and . . .
[img]cid:.1[/img]
Are incompatible with the design goal cited in the
article. So if your design goals include attention
to details of fire-wall integrity, then perhaps
single fat-wires are best brought through grommets
with fire-shields and application of fire-putty
per Tony B's writings.
Bob . . .
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grosseair(at)comcast.net
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| Posted: Tue Mar 16, 2010 6:51 am Post subject: Running Big Battery Wire Through Firewall |
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I'm sorry, but I'm not understanding something. The devices below look
more secure to me than a wire through a hole in the firewall filled with
fire putty. I can see that the bolt could conduct heat from a fire, but
then so could a wire. The concept with these devices seems the same to
me as a bulkhead fitting for hydraulic lines which is apparently okay.
So could someone explain why these electrical fittings are incompatible
with firewall security.
Thanks.
John Grosse
Robert L. Nuckolls, III wrote:
| Quote: | At 08:37 AM 3/10/2010, you wrote:
>
>
> 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...
I don't think I've yet seen a commercial-off-the-shelf firewall
feedthru where the insulating material would have stood off
Jack Thermin's "puff the magic dragon" test. Electrically
and mechanically, these critters function as advertised.
The price is low and they seem adequately robust.
However, if one subscribes to the notion of protecting
firewall integrity with processes like . . .
http://www.aeroelectric.com/articles/Firewall_Penetration/firewall.html
then devices like . . .
Emacs!
and . . .
Emacs!
Are incompatible with the design goal cited in the
article. So if your design goals include attention
to details of fire-wall integrity, then perhaps
single fat-wires are best brought through grommets
with fire-shields and application of fire-putty
per Tony B's writings.
Bob . . .
|
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william_slaughter(at)att.
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| Posted: Tue Mar 16, 2010 12:56 pm Post subject: Running Big Battery Wire Through Firewall |
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The plastic insulator portion would be incinerated within seconds, leaving a
hole in the firewall for the fire to pass through to the cockpit.
--
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grosseair(at)comcast.net
Guest
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| Posted: Tue Mar 16, 2010 2:08 pm Post subject: Running Big Battery Wire Through Firewall |
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Okay, I get that. I thought that was a metal part. Guess I should have
checked the specs.
John
William Slaughter wrote:
[quote]
The plastic insulator portion would be incinerated within seconds, leaving a
hole in the firewall for the fire to pass through to the cockpit.
--
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retasker(at)optonline.net
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| Posted: Tue Mar 16, 2010 2:27 pm Post subject: Running Big Battery Wire Through Firewall |
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Because the plastic holder melts/burns/disappears in a fire, leaving a
hole for fumes (and possibly creating fumes), flames and a short from
the "bolt" to the firewall.
Dick Tasker
John Grosse wrote:
| Quote: |
<grosseair(at)comcast.net>
I'm sorry, but I'm not understanding something. The devices below look
more secure to me than a wire through a hole in the firewall filled
with fire putty. I can see that the bolt could conduct heat from a
fire, but then so could a wire. The concept with these devices seems
the same to me as a bulkhead fitting for hydraulic lines which is
apparently okay. So could someone explain why these electrical
fittings are incompatible with firewall security.
Thanks.
John Grosse
Robert L. Nuckolls, III wrote:
> At 08:37 AM 3/10/2010, you wrote:
>>
>>
>> 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...
>
> I don't think I've yet seen a commercial-off-the-shelf firewall
> feedthru where the insulating material would have stood off
> Jack Thermin's "puff the magic dragon" test. Electrically
> and mechanically, these critters function as advertised.
> The price is low and they seem adequately robust.
>
> However, if one subscribes to the notion of protecting
> firewall integrity with processes like . . .
>
> http://www.aeroelectric.com/articles/Firewall_Penetration/firewall.html
>
> then devices like . . .
>
> Emacs!
> and . . .
>
> Emacs!
> Are incompatible with the design goal cited in the
> article. So if your design goals include attention
> to details of fire-wall integrity, then perhaps
> single fat-wires are best brought through grommets
> with fire-shields and application of fire-putty
> per Tony B's writings.
>
> Bob . . .
|
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Bob McC
Joined: 09 Jan 2006
Posts: 258
Location: Toronto, ON
|
| Posted: Tue Mar 16, 2010 6:03 pm Post subject: Running Big Battery Wire Through Firewall |
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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
| Quote: | Date: Mon, 15 Mar 2010 19:18:30 -0500
From: grosseair(at)comcast.net
To: aeroelectric-list(at)matronics.com
Subject: Re: Running Big Battery Wire Through Firewall
--> AeroElectric-List message posted by: John Grosse <grosseair(at)comcast.net>
I'm sorry, but I'm not understanding something. The devices below look
more secure to me than a wire through a hole in the firewall filled with
fire putty. I can see that the bolt could conduct heat from a fire, but
then so could a wire. The concept with these devices seems the same to
me as a bulkhead fitting for hydraulic lines which is apparently okay.
So could someone explain why these electrical fittings are incompatible
with firewall security.
Thanks.
John Grosse
Robert L. Nuckolls, III wrote:
> At 08:37 AM 3/10/2010, you wrote:
>> --> AeroElectric-List message posted by: <longg(at)pjm.com>
>>
>> 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...
>
> I don't think I've yet seen a commercial-off-the-shelf firewall
> feedthru where the insulating material would have stood off
> Jack Thermin's "puff the magic dragon" test. Electrically
> and mechanically, these critters function as advertised.
> The price is low and they seem adequately robust.
>
> However, if one subscribes to the notion of protecting
> firewall integrity with processes like . . .
>
> http://www.aeroelectric.com/articles/Firewall_Penetration/firewall.html
>
> then devices like . . .
>
> Emacs!
>
>
> and . . .
>
> Emacs!
> Are incompatible with the design goal cited in the
> article. So if your design goals include attention
> to details of fire-wall integrity, then perhaps
> single fat-wires are best brought through grommets
> with fire-shields and application of fire-putty
> per Tony B's writings.
>
> Bob .====================
|
[quote][b]
| | - 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:
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_________________
Bob McC
Falco #908
(just starting) |
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