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Old 06-30-2020, 06:10 PM   #1
sick472
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SFE 15 and 25 amp fuses - where are they?

I think our trucks take the 15 and 25 SFE fuses? But, Summit doesn't show them available, nor does Napa carry them.

AND where does the 15 amp SFE Hazard Flasher fuse go? OR is that just the rating for the flasher itself?

Forgive me...I'm deep into putting the wires back in (I'm no electrician, just a wanna be) and it's getting to my head...lol. What am I missing and/or what is everyone doing with respect to these fuses?
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Old 06-30-2020, 07:15 PM   #2
Steeveedee
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Re: SFE 15 and 25 amp fuses - where are they?

SFE 15 Hazard is the top right fuse in the block, labeled "TRF HAZ"

Grainger carries a high-amp fuse kit, but it looks like you have to order it.
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Old 06-30-2020, 09:19 PM   #3
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Re: SFE 15 and 25 amp fuses - where are they?

Our trucks take AGC fuses. The AG means automotive glass fuse and C means the physical size. You can get fuses at auto parts stores. Littlefuse is a common brand. A "blister pack" of 10 amp AGC fuses at O'Reilly Auto Parts has part number AGC10BP.

All of the fuses in the fuse panel are AGC fuses. If you have an ammeter on the instrument cluster, the fuses for those are SFE4 and they are in little fuse holders near the driver side headlight and battery. SFE fuses are different lengths for each amp rating, so a 4 amp SFE fuse is the only one that will fit in the stock fuse holder.

https://en.wikipedia.org/wiki/Fuse_(...lass_tube_type
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Old 06-30-2020, 10:31 PM   #4
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Re: SFE 15 and 25 amp fuses - where are they?

Then how do you explain the SAE/SFE nomenclature in the page he posted in the repair manual? Not trying to be confrontational. It's right there in the manual, though. I know that all these fuses for our trucks have a glass portion, so AGC makes sense.
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Old 06-30-2020, 11:17 PM   #5
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Re: SFE 15 and 25 amp fuses - where are they?

I think the Society of Fuse Engineers and the Society of Automotive Engineers got together over beers and drew up the specs. I think a LOT of beers were involved, and darts, billiards, and drawing of crude pictures on cocktail napkins. Their girlfriends finished off the specs by introducing the 3AG fuse size, which was the exact same size as AGC but had to have a different name, of course. By the end of that night, it was all figured out. That's my guess. We gotta have many names for the same thing.
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Old 07-01-2020, 01:54 AM   #6
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Re: SFE 15 and 25 amp fuses - where are they?

I just have to question why you feel the need to order fuses from Summit rather than gong to Napa or another full service parts house. They may not have them on the shelf but can have them on the next stock order.
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Old 07-01-2020, 09:38 AM   #7
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Re: SFE 15 and 25 amp fuses - where are they?

I suppose, if someone could prove that AGC and SFE fuses are interchangeable, I would not have a problem going against the manual. The problem might then pop up that the SFE fuses are different lengths depending on the amp rating and a AGC fuse (all the same length) may not fit the hole.

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Originally Posted by mr48chev View Post
I just have to question why you feel the need to order fuses from Summit rather than gong to Napa or another full service parts house...
I went to Napa first and they did not show the SFE's in the books at 15 and 25 amps. All they had were the 20's.

Summit is a great placed to see what's available, they have most everything...you just have to watch some of the prices and compare to local availability.

Quote:
Originally Posted by Steeveedee View Post
SFE 15 Hazard is the top right fuse in the block, labeled "TRF HAZ"

Grainger carries a high-amp fuse kit, but it looks like you have to order it.
Thanks for pointing out the "TRF HAZ" fuse location Steve..good thing it was not a snake! I jumped on Grainger's site and all they offer in the SFE's are 4, 6, 7-1/2, 9, 14, 20, & 30...same as Napa and Summit...same as what the above Wiki site states as available.

It's like the Chevy AND fuse engineers were drinking a bit too much OR the 15 and 25 amp SFE fuses slipped into the Twilght Zone while they were sleeping off the hangovers.

The available 15 and 25 amp AGC fuses are 1-1/4" long...IF the SFE 15 exists, it would be somewhere between the SFE 14 & 20 in length (1-1/16 to 1-1/4" lg)...So, the AGC 15 would likely fit in the hole. The imaginary SFE 25 would be between the SFE 20 & 30 which would put it's length around 1-1/3". That still might fit in the hole...I have to measure it when I get to the shop. Best I can tell by reading between the internet lines (keeping in mind that the internet is NOT always right), the AGC & SFE are both fast acting fuses...the SFE may be a bit faster, but are considered interchangeable so long as they fit the hole and have plenty of contact at the fuse holders.
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Old 07-01-2020, 03:36 PM   #8
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Re: SFE 15 and 25 amp fuses - where are they?

Like most things 50 years old parts have evolved and been superseded. The letter prefixes on fuses relate to size groups, voltage ratings and many times relate to how fast the fuse will blow at the rated voltage and amperage. Some fuses are rated as "slow blow" meaning they will tolerate over current conditions for longer periods of time. This link will help guide you to suitable replacement fuses.

https://www.optifuse.com/crossbus.php

Let's not forget that in the world of fuse protection our trucks only had the crudest and simplest form of protection from the factory, since that was all that was needed. No sophisticated electronics here. So if the voltage and amperage rating is the same, the size is the same and the internal element is the same basic size and shape the fuse will provide the all the protection need for one of our stock trucks. How many of you have bought a running driving vehicle only to discover later one of the fuses had been replaced with a gum wrapper?
If you have added aftermarket equipment then be sure to fuse it according to the manufacturer's requirements.
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Old 07-01-2020, 03:42 PM   #9
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Re: SFE 15 and 25 amp fuses - where are they?

Quote:
Originally Posted by HO455 View Post
Like most things 50 years old parts have evolved and been superseded. The letter prefixes on fuses relate to size groups, voltage ratings and many times relate to how fast the fuse will blow at the rated voltage and amperage. Some fuses are rated as "slow blow" meaning they will tolerate over current conditions for longer periods of time. This link will help guide you to suitable replacement fuses.

https://www.optifuse.com/crossbus.php

Let's not forget that in the world of fuse protection our trucks only had the crudest and simplest form of protection from the factory, since that was all that was needed. No sophisticated electronics here. So if the voltage and amperage rating is the same, the size is the same and the internal element is the same basic size and shape the fuse will provide the all the protection need for one of our stock trucks. How many of you have bought a running driving vehicle only to discover later one of the fuses had been replaced with a gum wrapper?
If you have added aftermarket equipment then be sure to fuse it according to the manufacturer's requirements.
Heh, where I used to work we had remote controlled positioning equipment for antenna testing. Sometimes there would be an intermittent problem. We all know what that's like. The range maintenance guy would come out, and not find the problem, since the equipment decided to work again. One guy's solution was to put in a "#10-32 AGC fuse", as he called it. Then range maintenance was called, and the melted/scorched component replaced. That guy is lucky nothing got burnt down with a machine screw instead of a fuse in the slot.
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Old 07-02-2020, 09:42 AM   #10
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Re: SFE 15 and 25 amp fuses - where are they?

-
I have mixed and matched AGC & SFE fuses for MANY years with no ill effects. As long as you use the correct amperage it makes no difference.

I buy mine at swap meets pretty cheap, and stock up when I see them....

Just my 2 worth.

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Old 07-02-2020, 09:48 AM   #11
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Re: SFE 15 and 25 amp fuses - where are they?

Thanks for chiming in Leon! Just the confidence boost I needed. Certainly worth more than 2.
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