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Bob Barrow
Joined: 11 Jan 2006
Posts: 29
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 Posted: Fri Jul 17, 2009 7:06 pm Post subject: Fat feed confusion |
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I note in a June post that Bob Nuckolls said that "fat feed" wires (6 AWG or larger) do not need a fuse or current limiter. I understand the logic behind that.
However I note in the Nuckolls Z14 architecture that the wire between the Crossfeed Contactor and the Auxiliary Bus is 10 AWG and has no protection.
Why is this an exception to the rule.
Make ninemsn your homepage! Get the latest news C goss and sport [quote][b]
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william_slaughter(at)att.
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| Posted: Sat Jul 18, 2009 3:35 am Post subject: Fat feed confusion |
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A 10 AWG wire is smaller than a 6 AWG, not larger. In wire gauge notation a low number is a big wire, a higher number is a smaller wire.
William Slaughter
From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Bob Barrow
Sent: Friday, July 17, 2009 10:03 PM
To: aeroelectric-list(at)matronics.com
Subject: Fat feed confusion
I note in a June post that Bob Nuckolls said that "fat feed" wires (6 AWG or larger) do not need a fuse or current limiter. I understand the logic behind that.
However I note in the Nuckolls Z14 architecture that the wire between the Crossfeed Contactor and the Auxiliary Bus is 10 AWG and has no protection.
Why is this an exception to the rule.
Make ninemsn your homepage! Get the latest news, goss and sport | Quote: | | http://www.matronics.com/Navigator?AeroElectric-List |
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[quote][b]
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icubob(at)gmail.com
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| Posted: Sat Jul 18, 2009 4:18 am Post subject: Fat feed confusion |
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william,
since 10 ga is smaller than 6ga that is why the question ''why no protection''.
bob noffs
On Sat, Jul 18, 2009 at 6:32 AM, William Slaughter <william_slaughter(at)att.net (william_slaughter(at)att.net)> wrote:
[quote]
A 10 AWG wire is smaller than a 6 AWG, not larger. In wire gauge notation a low number is a big wire, a higher number is a smaller wire.
William Slaughter
From: owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com) [mailto:owner-aeroelectric-list-server(at)matronics.com (owner-aeroelectric-list-server(at)matronics.com)] On Behalf Of Bob Barrow
Sent: Friday, July 17, 2009 10:03 PM
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Subject: Fat feed confusion
I note in a June post that Bob Nuckolls said that "fat feed" wires (6 AWG or larger) do not need a fuse or current limiter. I understand the logic behind that.
However I note in the Nuckolls Z14 architecture that the wire between the Crossfeed Contactor and the Auxiliary Bus is 10 AWG and has no protection.
Why is this an exception to the rule.
Make ninemsn your homepage! Get the latest news, goss and sport 012 34567 89
0
[b]
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nuckollsr
Joined: 24 Mar 2009
Posts: 95
Location: Medicine Lodge, KS
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| Posted: Mon Jul 20, 2009 6:05 am Post subject: Re: Fat feed confusion |
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Sharp eye! I think that's a typo. To qualify as a "fat feeder" with inherent resistance to ground-fault-burning of wire/insulation, the current carrying ability of the wire compared with highest hypothesized fault needs to be pretty high. While the 10AWG buss feeder is adequate to the task of servicing electro-whizzies that load the 20A alternator, it's also small enough to be at risk for burning the length of the wire along with the attendant risk of smoke in the cockpit, etc.
We have two choices here to slide this feeder under the umbrella of legacy design goals: (a) add a fusible link to the feed-end of this wire (6" of 14 AWG would be fine) or (b) increase the 10AWG feeder to at least a 6AWG. Since we're already wired with lots of 4AWG, that would be good too.
Actually, there's a third option. We bought the Delrin stock from which we can fabricate mounting blocks for the minature robust, ANL style fuses. See
http://aeroelectric.com/Pictures/Fuses/Fuses/ABI_fuses.jpg
http://aeroelectric.com/Pictures/Fuses/Fuses/megafuse250.gif
http://www.knukonceptz.com/productMaster.cfm?category=Mini-ANL%20Fuse#
We're going to stock one of these fuse topologies and offer a mounting block to to with it. But these can be fabricated locally from the right nuts, washers, screws, and block of Delrin or cloth filled phenolic.
While on the subject of fuses, check out this little treatis I found on the 'net. Nicely done . . .
http://www.bcae1.com/fuses.htm
Note the author's caveat concerning the quality levels of glass cartridge fuses.
Bob . . .
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pwmac(at)sisna.com
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| Posted: Mon Jul 20, 2009 7:39 am Post subject: Fat feed confusion |
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When we put a high amp alternator in the truck we used a fuse with
holder to protect against alt internal failure. Same kind should work
fine for the batt feeder as recommended by Littelfuse?
http://www.littelfuse.com/part/0298175.html No need to fabricate a
holder. Pretty common in my truck world.
Use it in-line or bolt it to the structure. Very low tech and functional.
PW
==========
At 08:05 AM 7/20/2009, you wrote:
| Quote: |
<bob.nuckolls(at)aeroelectric.com>
Sharp eye! I think that's a typo. To qualify as a "fat feeder" with
inherent resistance to ground-fault-burning of wire/insulation, the
current carrying ability of the wire compared with highest
hypothesized fault needs to be pretty high. While the 10AWG buss
feeder is adequate to the task of servicing electro-whizzies that
load the 20A alternator, it's also small enough to be at risk for
burning the length of the wire along with the attendant risk of
smoke in the cockpit, etc.
We have two choices here to slide this feeder under the umbrella of
legacy design goals: (a) add a fusible link to the feed-end of this
wire (6" of 14 AWG would be fine) or (b) increase the 10AWG feeder
to at least a 6AWG. Since we're already wired with lots of 4AWG,
that would be good too.
Actually, there's a third option. We bought the Delrin stock from
which we can fabricate mounting blocks for the minature robust, ANL
style fuses. See
http://aeroelectric.com/Pictures/Fuses/Fuses/ABI_fuses.jpg
http://aeroelectric.com/Pictures/Fuses/Fuses/megafuse250.gif
http://www.knukonceptz.com/productMaster.cfm?category=Mini-ANL%20Fuse#
We're going to stock one of these fuse topologies and offer a
mounting block to to with it. But these can be fabricated locally
from the right nuts, washers, screws, and block of Delrin or cloth
filled phenolic.
While on the subject of fuses, check out this little treatis I found
on the 'net. Nicely done . . .
http://www.bcae1.com/fuses.htm
Note the author's caveat concerning the quality levels of glass
cartridge fuses.
Bob . . .
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p 53876#253876
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nuckolls.bob(at)aeroelect
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| Posted: Mon Jul 20, 2009 11:37 am Post subject: Fat feed confusion |
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At 10:36 AM 7/20/2009, you wrote:
| Quote: |
When we put a high amp alternator in the truck we used a fuse with
holder to protect against alt internal failure. Same kind should
work fine for the batt feeder as recommended by Littelfuse?
http://www.littelfuse.com/part/0298175.html No need to fabricate a
holder. Pretty common in my truck world.
Use it in-line or bolt it to the structure. Very low tech and functional.
|
Yup, that's a righteous product. It's a miniaturize
version of the 70 year old ANN/ANL series devices.
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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