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Thread: Amp size and power cord gauge

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    Supporting Member Randall's Avatar
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    Amp size and power cord gauge

    I am putting a new 3 prong power cable on a 72 Ampeg V2. The fuse is rated at 4 amps (in series with an internal 6 amp, what's up with that) and the original cord has no info on the jacket, but it looks like 16 gauge. The hole and retainer will accomodate the old 16/2 (assuming that is what it is), but is too small for 16/3 (at least what I have). Is it safe to go down to 18/3, which is what I put on most other smaller amps? Or is there maybe a smaller diameter 16/3 I could use?

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    Last edited by Randall; 02-19-2019 at 09:43 PM.
    It's weird, because it WAS working fine.....

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    Senior Member nevetslab's Avatar
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    Quote Originally Posted by Randall View Post
    I am putting a new 3 prong power cable on a 72 Ampeg V2. The fuse is rated at 4 amps and the original cord has no info on the jacket, but it looks like 16 gauge. The hole and retainer will accomodate the old 16/2 (assuming that is what it is), but is too small for 16/3 (at least what I have). Is it safe to go down to 18/3, which is what I put on most other smaller amps? Or is there maybe a smaller diameter 16/3 I could use?
    18/3 cordage is good up to 7A continuous (30 deg C ambient). 16/3 is good up to 10A, 14/3 good up to 15A, 12/3 good up to 20A.

    UL_CSA_Power Cord Current Ratings.pdf

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    Last edited by nevetslab; 02-19-2019 at 09:55 PM.
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    Supporting Member Randall's Avatar
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    Thanks nevetslab!

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    It's weird, because it WAS working fine.....

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    Lifetime Member Enzo's Avatar
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    (in series with an internal 6 amp, what's up with that
    A common enough Ampeg trick. That is done so that if you blow the 4A fuse and stick a 15A fuse in there instead, the amp still has fuse protection inside.

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    Senior Member SoulFetish's Avatar
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    Quote Originally Posted by Enzo View Post
    A common enough Ampeg trick. That is done so that if you blow the 4A fuse and stick a 15A fuse in there instead, the amp still has fuse protection inside.
    Ampeg was clever enough to know their customer base!
    I've seen enough that I try and remember to check the fuse value of each amp that comes in, regardless of the reason for service (particularly in vintage amps). I just worked on a blackface deluxe which had a 32V/15A fuse on the mains. But I haven't seen the infamous tinfoil bypass mod yet, which is.... encouraging?

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    Maybe we should call the internal a "Beavis Fuse" or "Dim-Bulb Fuse." I'll not forget getting my Bassman home & finding a 20A fuse in it... Now no amp comes home without pulling the fuse first.

    Justin

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    Lifetime Member Enzo's Avatar
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    I did once find a piece of 1/4" bolt cut to length and stuck in a fuse clip.

    In their defense, is was one of those gold plated bolts like they use in car stereo setups.

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    Quote Originally Posted by Enzo View Post
    I did once find a piece of 1/4" bolt cut to length and stuck in a fuse clip.

    In their defense, is was one of those gold plated bolts like they use in car stereo setups.
    I used to see 1/4 aluminum dowel from time to time cut to length in fuse recepticles. That and speaker protection relay covers put on sideways to keep the contacts closed...

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