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Old 26-09-2020, 13:09   #1
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Wire size

My solar panels use 12ga wire to the main panel.
I would like to add a analogue amp gauge into the circuit.
The gauge I have has 18 or 20ga wires 6” long each (total length 12”) to go in series With the 12ga wires. This length could be shortened.
I know that shorter length of wires can carry larger amps, but this seems to drastic.
Amperage is often equated to water. Larger pipes (wires)can carry a larger flow of water (amps). If a smaller pipe(wire) is installed it reduces the flow of water (amps).
It would seem that installing a 18/20 ga length of wire would have a similar effect.
I could install a digital gauge with no effect on the wiring size, but I was looking for the increased accuracy of the analogue gauge.
Comments would be appreciated.
Thanks. Nick
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Old 26-09-2020, 13:54   #2
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Re: Wire size

What is the maximum current produced by the panes(s)?

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Old 26-09-2020, 14:05   #3
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Re: Wire size

Max panel 10amp +/-
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Old 26-09-2020, 14:22   #4
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Re: Wire size

Most shunts for that amperage are built into the gauges. Larger amperage usually uses shunts separate from the gauges. True for both digital and analog.


A short length of smaller wire would be OK if you're just connecting the gauge to your main wire run. Your analogy is apt, although "...If a smaller pipe(wire) is installed it reduces the flow of water (amps)..." is only partially true. The smaller pipe or wire CAN, within reason, carry the same flow but with increased resistance.


Ammeters & Shunts 101 http://c34.org/bbs/index.php/topic,6032.0.html


Good luck.
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Old 26-09-2020, 14:32   #5
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Re: Wire size

Thanks. Yes the smaller pipe would have a higher pressure.
It seems a short lgt. of smaller wire will be ok.
I’ll keep it as short as possible.
Thanks again, Nick
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Old 26-09-2020, 17:22   #6
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Re: Wire size

Are you sure those are not data cables for a shunt?

If this is an in-line meter with 18 or 20awg I would not use it.

20awg can not be used for power. 18awg is limited to 1a via abyc. 16awg is the smallest power wire allowed.

Sounds like Your gauge is junk.
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Old 26-09-2020, 17:33   #7
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Re: Wire size

Quote:
Originally Posted by Cat Nap3 View Post
My solar panels use 12ga wire to the main panel.
I would like to add a analogue amp gauge into the circuit.
The gauge I have has 18 or 20ga wires 6” long each (total length 12”) to go in series With the 12ga wires. This length could be shortened.
I know that shorter length of wires can carry larger amps, but this seems to drastic.
Amperage is often equated to water. Larger pipes (wires)can carry a larger flow of water (amps). If a smaller pipe(wire) is installed it reduces the flow of water (amps).
It would seem that installing a 18/20 ga length of wire would have a similar effect.
I could install a digital gauge with no effect on the wiring size, but I was looking for the increased accuracy of the analogue gauge.
Comments would be appreciated.
Thanks. Nick
To have an analog ammeter you need a shunt. It may be internal for a ammeter which handles low amp loads (such as your 10 amp). Or external shunt, on which the wires from your solar panel goes directly to the shunt, and then smaller wires in parallel with the shunt go to the gauge. I think your gauge has an internal shunt. I would not put 18/20 ga wire, of any length, in series with your solar output.

I have an internally shunted analog gauge on my solar output which reads 0-20 amps. The solar output wires go directly to the gauge, not to any smaller wires. My wires are 10ga.
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Old 26-09-2020, 18:46   #8
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Re: Wire size

If wired in series, it would not be a good idea to insert a length of smaller gauge wire. I suggest coughing up the $20 and using the same 12 gauge wire as the rest of the circuit.
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