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Same rating for fuses and circuit breakers?

 
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PostPosted: Tue Oct 23, 2018 11:41 am    Post subject: Same rating for fuses and circuit breakers? Reply with quote

I think he means because you can't get the glow-when-blown fuses smaller than 3amp. A 3amp fuse is able to protect a 24-gauge wire so I'm not sure there's any reason to use smaller fuses. I don't have any wires smaller than that in my plane anyway. That said, there's nothing wrong with using smaller if a manufacturer calls for it and you don't mind that it doesn't light up.
--Rick

On 10/23/2018 3:11 PM, Art Zemon wrote:

Quote:
Joe,


Why do you say not to use a fuse smaller than 3 amps? My backup ASI/altimeter came with installation instructions calling for a 1 amp slow blow fuse. I splurged the $1.02 and installed it. 


    -- Art Z.

On Tue, Oct 23, 2018 at 1:52 PM user9253 <fransew(at)gmail.com (fransew(at)gmail.com)> wrote:

Quote:
--> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)>

Here is my opinion:
Use the same size.
Do not use fuses smaller than 3 amps. 



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PostPosted: Tue Oct 23, 2018 11:53 am    Post subject: Same rating for fuses and circuit breakers? Reply with quote

I'll jump in, because that's one of my pet peeves. First, the mfgr of a widget shouldn't be asking the end user to supply protection for their device. Circuit protection protects circuits; not devices. If the mfgr thinks their device needs a 1A fuse, it should be in the device. Ever seen a piece of consumer or industrial electronics that came with a requirement that you supply its fusing? (They tell you the *minimum* size circuit needed; not a spec for device protection.)  Second, a 1A fuse isn't going to protect anything; the equipment will either die before the fuse blows, or the fuse will be blowing needlessly on a more or less random (possibly regular) basis. That's likely why Joe said not to use any fusing under 3A; a policy I also use.

Charlie

On 10/23/2018 2:11 PM, Art Zemon wrote:

Quote:
Joe,


Why do you say not to use a fuse smaller than 3 amps? My backup ASI/altimeter came with installation instructions calling for a 1 amp slow blow fuse. I splurged the $1.02 and installed it. 


    -- Art Z.

On Tue, Oct 23, 2018 at 1:52 PM user9253 <fransew(at)gmail.com (fransew(at)gmail.com)> wrote:

Quote:
--> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)>

Here is my opinion:
Use the same size.
Do not use fuses smaller than 3 amps. 



--
https://CheerfulCurmudgeon.com/ "We do not see the world as it is. We see the world as we are."














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Kellym



Joined: 10 Jan 2006
Posts: 1548
Location: Sun Lakes AZ

PostPosted: Tue Oct 23, 2018 12:51 pm    Post subject: Same rating for fuses and circuit breakers? Reply with quote

I seem to recall there is a reason that ammeters call for a 1 amp fuse
on each lead from the shunt. It certainly isn't for wire protection,
maybe to protect the meter movement.

On 10/23/2018 12:44 PM, Charlie England wrote:
Quote:
I'll jump in, because that's one of my pet peeves. First, the mfgr of a
widget shouldn't be asking the end user to supply protection for their
device. Circuit protection protects circuits; not devices. If the mfgr
thinks their device needs a 1A fuse, it should be in the device. Ever
seen a piece of consumer or industrial electronics that came with a
requirement that you supply its fusing? (They tell you the *minimum*
size circuit needed; not a spec for device protection.)  Second, a 1A
fuse isn't going to protect anything; the equipment will either die
before the fuse blows, or the fuse will be blowing needlessly on a more
or less random (possibly regular) basis. That's likely why Joe said not
to use any fusing under 3A; a policy I also use.

Charlie

On 10/23/2018 2:11 PM, Art Zemon wrote:
> Joe,
>
> Why do you say not to use a fuse smaller than 3 amps? My backup
> ASI/altimeter came with installation instructions calling for a 1 amp
> slow blow fuse
> <https://www.digikey.com/product-detail/en/littelfuse-inc/0218001.HXP/F2419-ND/777135>.
> I splurged the $1.02 and installed it.
>
>   -- Art Z.
>
> On Tue, Oct 23, 2018 at 1:52 PM user9253 <fransew(at)gmail.com
> <mailto:fransew(at)gmail.com>> wrote:
>
>
> <fransew(at)gmail.com <mailto:fransew(at)gmail.com>>
>
> Here is my opinion:
> Use the same size.
> Do not use fuses smaller than 3 amps.
>
> --
> https://CheerfulCurmudgeon.com/
>
> /"We do not see the world as it is. We see the world as we are."/


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PostPosted: Sun Oct 28, 2018 9:07 am    Post subject: Same rating for fuses and circuit breakers? Reply with quote

Actually I think you will find that a GFI activates when the outgoing
and incoming current does not match.  ie there is current going
somewhere other than the intended load.  I don't see how you can compare
the two values if a device does not have a dedicated return ground
wire.   Residential GFI's trip upon seeing about 5 ma difference.  I
don't see that AC or DC matters but I'm open to learning something new.
Ken

On 28/10/2018 12:27 PM, FLYaDIVE wrote:
Quote:
Bob:

Of course GFI will not work on planes, not as yet! The present GFI for
homes uses inductance in the AC circuit.  Our planes are DC,
inductance is not there, AC is not there!
The type of Ground does not matter.

Barry


On Sat, Oct 27, 2018 at 10:59 AM Robert L. Nuckolls, III
<nuckolls.bob(at)aeroelectric.com <mailto:nuckolls.bob(at)aeroelectric.com>>
wrote:

At 09:41 AM 10/26/2018, you wrote:
> At 07:29 PM 10/25/2018, you wrote:
>> Right You Are Charlie:
>>
>> Here is another thought?
>> In the AC world there is a thing know as a Ground Fault
>> Interrupt (GFI)  ...  Barry

>

  So I'll correct my earlier assertion . . . GFIs
  don't exist for aircraft. In fact, they wouldn't
  work in a system that specifically uses airframe
  ground as the return power path.

  Bob . . .



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harleydixon



Joined: 17 Sep 2016
Posts: 12
Location: Henrietta, NY

PostPosted: Sun Oct 28, 2018 9:50 am    Post subject: Same rating for fuses and circuit breakers? Reply with quote

Don't forget to take into consideration the FUTURE costs of building your own plane.  The MUCH lower cost of adding new, not necessarily STC'd, equipment, and the saving when doing your own maintenance and annuals...even at a high initial cost (IF you consider the hours when you would normally be watching football!) in the end, it's far less costly to own and operate a plane you've built.  And, as Dick said, the experience and education of building your own and the satisfaction of flying something you built is priceless. 

And, that's why I built my Long EZ!

Harley

On 10/28/2018 1:41 PM, Dick Tasker wrote:

Quote:
--> AeroElectric-List message posted by: Dick Tasker <dick(at)thetaskerfamily.com> (dick(at)thetaskerfamily.com)

Not sure how long it has taken you to build your plane, but mine certainly isn't worth hundreds of thousands at the McDonald's rate.

Yes, at the rate of my actual job it would start getting into that range, but I didn't build to save money (although some people do). I could have just purchased a plane, but I built it for the fun and education experience and ability to modify it how I want to.

And Bob is not averse to spending money.  He is just averse to spending money where it really has no useful benefit.  But he certainly doesn't have a problem if you want to spend money on your plane for what you think is worth it.  On the other hand, money spent on something with no significant benefit is money not available for gas and actually flying.

Dick Tasker

FLYaDIVE wrote:
Quote:
Bob:

You are a COMPANY MAN, you think too much of ridiculous things like the CO$T to install a device.
The fellows out there do not think of the "cost/benefit ratio" , for if they did they would NEVER build a plane.
Guys, if you think my statement is incorrect just sit down and work out thee TRUE hours you invested in the building of your plane.
At a Very Conservative rate of say $2.00 / Hour - Just In Labor - Work out how much your plane has cost you.
Then take the $2.00 / Hr rate and replace it with your TRUE hourly work rate that you are being paid in your current job.
Even if you worked at McDonald's - Considering their hourly rate...  Your plane would be worth Hundreds of Thousands of Dollars and that is JUST for the LABOR!




On Fri, Oct 26, 2018 at 10:44 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com) <mailto:nuckolls.bob(at)aeroelectric.com> (nuckolls.bob(at)aeroelectric.com)> wrote:

    At 08:05 PM 10/25/2018, you wrote:
Quote:
    Thanks Don,

    Ya know guys, the circuit is so simple it can be added to a CB. probably easier than a fuse.
    Good for the CB that is out of the standard field of view.

    Barry

      But what is the cost/benefit ratio? 99.99% of all
      breakers/fuses installed in all vehicles at the
      factory go to the junkyard never having been
      tasked to do their job.

      For every fault that takes a system down by
      opening the power feeder protection, there
      are MANY more faults equally deleterious
      to system operation that do not open the
      feeder protection.

Barry - Yeah, so???   I don't see your point.
Are you concerned about the CO$T again?
Or the Quantity of indicating fuses/CB'ers installed?
It does not have to be on every fuse/CB, only the ones the Builder/Pilot thinks they would like a bit more information from.


      When circuit protection does operate in
      a thoughtfully designed system, the thing
      is broke. Resetting the breaker or replacing
      the fuse will not bring it back.

Barry - It WON'T!!!???
Then why even have a resealable CB?
Why is the in-flight procedure of Resetting a CB only once while in the air, taught?
There is one poor design on a certified plane where the Strobes and the Boost Pump are on the same CB.  There have been reports where if the Boost Pump is left on during Start the CB will pop.  Of course a smart pilot will shut-off the boost pump after the system is pressurized.  But, human nature being what it is... Pilots will forget to shut-off the boost pump.  So, I guess a resealable CB is a wast of money?


      The pilot's first clue that something is
      amiss is when an expected event doesn't
      occur on the airplane . . . but what value
      is there in knowing the state of power
      feeder protection? The reason for malfunction
      is not relevant to the pilot's prime
      directive: effect a return to earth
      without bending airplanes or people.

Barry - Yeah! There is NO Value in saving a few seconds and calming the mind when something goes wrong and does not function as it should.  I guess that is why companies like E.I., JPI and Safe Air  have separate Idiot Lights so they can be mounted directly in your field of view.
Just to warn you seconds sooner...  Any IFR pilots out there?  Anyone have a Low Vacuum Warning Light? Get rid of it. You don't need it!  Bob said so.
Whoops, I'm VFR and I have one on my VFR plane!
Not for long as I'm going G5.
Indicating fuses are cute but the feature

      saves only seconds of diagnostic time which
      is done on the ground.

Barry - O!  I guess you and no one else out there EVER experienced a fuse or CB to pop in the air???
I think you should go back and read past posts of electrical/alternator issues where they popped ONLY during flight!

Your Green is showing!

It was ONLY a thought.

Barry



      Bob . . .

































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PostPosted: Sun Oct 28, 2018 9:57 am    Post subject: Same rating for fuses and circuit breakers? Reply with quote

All,

There appears to be a lot of mythology surrounding GFCIs (Ground Fault Circuit Interrupters) or GFI for short.
Here's how they work:
1. GFI are anti-electrocution devices. Not over-current protection devices. (A very common mis-conception)

2. The GFI measures the current on both legs of the circuit, the hot and the neutral.
3. If it detects and imbalance between the two legs, it trips. It has nothing to do with the magnitude of the overall current. That's what the circuit breaker is for. I think the imbalance is as small as 5 mA (not sure but it is pretty small).
The theory is that if, for example, the hot leg is conducting 1000 mA but the current in the returning neutral is only 995mA, then 5mA of stray current is going somewhere bad, like thru your heart to ground.

Side Note (for electrical contractors):

Therefore a GFI cannot be use on a shared-neutral circuit - if you don't know what that is, don't worry about it. It is a fairly common practice in house wiring.

Comments:
1. Since GFI are anti-electrocution devices, they are generally not needed on low-voltage systems like the 12V ones in our planes. So they don't really apply to OBAM stuff.
2. In theory, you could make a 12v DC GFI using the same principle explained above. (But why bother?) It is not necessarily an AC or DC thing.

-Jeff
On Sunday, October 28, 2018 9:43 AM, FLYaDIVE <flyadive(at)gmail.com> wrote:



Bob:
Of course GFI will not work on planes, not as yet! The present GFI for homes uses inductance in the AC circuit. Our planes are DC, inductance is not there, AC is not there!
The type of Ground does not matter.
Barry

On Sat, Oct 27, 2018 at 10:59 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

Quote:
At 09:41 AM 10/26/2018, you wrote:
Quote:
At 07:29 PM 10/25/2018, you wrote:
Quote:
Right You Are Charlie:

Here is another thought?
In the AC world there is a thing know as a Ground Fault Interrupt (GFI) ... Barry


Quote:
Quote:


So I'll correct my earlier assertion . . . GFIs
don't exist for aircraft. In fact, they wouldn't
work in a system that specifically uses airframe
ground as the return power path.

Bob . . .



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John M Tipton



Joined: 07 Aug 2018
Posts: 10
Location: Devon - England

PostPosted: Sun Oct 28, 2018 10:41 am    Post subject: Same rating for fuses and circuit breakers? Reply with quote

This is getting silly now —-

Sent from my iPad

----x--O--x----

Quote:
On 28 Oct 2018, at 5:41 pm, Dick Tasker <dick(at)thetaskerfamily.com> wrote:



Not sure how long it has taken you to build your plane, but mine certainly isn't worth hundreds of thousands at the McDonald's rate.

Yes, at the rate of my actual job it would start getting into that range, but I didn't build to save money (although some people do). I could have just purchased a plane, but I built it for the fun and education experience and ability to modify it how I want to.

And Bob is not averse to spending money. He is just averse to spending money where it really has no useful benefit. But he certainly doesn't have a problem if you want to spend money on your plane for what you think is worth it. On the other hand, money spent on something with no significant benefit is money not available for gas and actually flying.

Dick Tasker

FLYaDIVE wrote:
> Bob:
>
> You are a COMPANY MAN, you think too much of ridiculous things like the CO$T to install a device.
> The fellows out there do not think of the "cost/benefit ratio" , for if they did they would NEVER build a plane.
> Guys, if you think my statement is incorrect just sit down and work out thee TRUE hours you invested in the building of your plane.
> At a Very Conservative rate of say $2.00 / Hour - Just In Labor - Work out how much your plane has cost you.
> Then take the $2.00 / Hr rate and replace it with your TRUE hourly work rate that you are being paid in your current job.
> Even if you worked at McDonald's - Considering their hourly rate... Your plane would be worth Hundreds of Thousands of Dollars and that is JUST for the LABOR!
>
>
>
>
> On Fri, Oct 26, 2018 at 10:44 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com <mailto:nuckolls.bob(at)aeroelectric.com>> wrote:
>
> At 08:05 PM 10/25/2018, you wrote:
>> Thanks Don,
>>
>> Ya know guys, the circuit is so simple it can be added to a CB. probably easier than a fuse.
>> Good for the CB that is out of the standard field of view.
>>
>> Barry
>
> But what is the cost/benefit ratio? 99.99% of all
> breakers/fuses installed in all vehicles at the
> factory go to the junkyard never having been
> tasked to do their job.
>
> For every fault that takes a system down by
> opening the power feeder protection, there
> are MANY more faults equally deleterious
> to system operation that do not open the
> feeder protection.
>
> Barry - Yeah, so??? I don't see your point.
> Are you concerned about the CO$T again?
> Or the Quantity of indicating fuses/CB'ers installed?
> It does not have to be on every fuse/CB, only the ones the Builder/Pilot thinks they would like a bit more information from.
>
>
> When circuit protection does operate in
> a thoughtfully designed system, the thing
> is broke. Resetting the breaker or replacing
> the fuse will not bring it back.
>
> Barry - It WON'T!!!???
> Then why even have a resealable CB?
> Why is the in-flight procedure of Resetting a CB only once while in the air, taught?
> There is one poor design on a certified plane where the Strobes and the Boost Pump are on the same CB. There have been reports where if the Boost Pump is left on during Start the CB will pop. Of course a smart pilot will shut-off the boost pump after the system is pressurized. But, human nature being what it is... Pilots will forget to shut-off the boost pump. So, I guess a resealable CB is a wast of money?
>
>
> The pilot's first clue that something is
> amiss is when an expected event doesn't
> occur on the airplane . . . but what value
> is there in knowing the state of power
> feeder protection? The reason for malfunction
> is not relevant to the pilot's prime
> directive: effect a return to earth
> without bending airplanes or people.
>
> Barry - Yeah! There is NO Value in saving a few seconds and calming the mind when something goes wrong and does not function as it should. I guess that is why companies like E.I., JPI and Safe Air have separate Idiot Lights so they can be mounted directly in your field of view.
> Just to warn you seconds sooner... Any IFR pilots out there? Anyone have a Low Vacuum Warning Light? Get rid of it. You don't need it! Bob said so.
> Whoops, I'm VFR and I have one on my VFR plane!
> Not for long as I'm going G5.
> Indicating fuses are cute but the feature
>
> saves only seconds of diagnostic time which
> is done on the ground.
>
> Barry - O! I guess you and no one else out there EVER experienced a fuse or CB to pop in the air???
> I think you should go back and read past posts of electrical/alternator issues where they popped ONLY during flight!
>
> Your Green is showing!
>
> It was ONLY a thought.
>
> Barry
>
>
>
> Bob . . .
>






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