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py26129

Adler Barbour Cold Machine wiring

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Hello

I am replacing the DC wiring to my Cold Machine.  Some previous owner had wired it using outdoor wire (solid copper).   

Based on the cable run, the table in the Cold Machine installation manual  specifies 8 gauge wire in order to prevent excessive voltage drop. The issue is that the connectors at the compressor end are .25" spade connectors which do not seem to be available for 8 gauge wire.

10 gauge connectors don't work with 8 gauge wire, so the question is:

Since the heavy wire is required to prevent a voltage drop, would it be acceptable to have a short length of 10 gauge wire (say 6" or less) at the compressor end to accommodate the connector?

IIRC the circuit is protected by a 10 amp breaker.

Flame away
 

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That works fine. You could also run the 8 gauge to a terminal strip and run 10 gauge from there to the unit.

This may be blasphemy, but you could also cut a few wire strands on the 8 gauge so the 10 gauge connectors can be installed, then heatshrink the end to protect and strain relieve it. This minimizes the number of crimp/screw connections and maximizes the length of the 8 gauge run. Note that it's good to anchor and support the heavy/stiff 8 gauge wire close to the spade connectors so they don't take the strain.

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Thanks for the quick response.  

Option 2 had occurred to me but it seemed even more of a kludge than option 1.  Good point about securing the wire close to the terminal.

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I'd take Option 2 in the real world any day.

A terminal strip, while probably best practice and the approved way to do it just introduces a lot more connections where resistance could increase.

A 8-10 step down butt connector would be a very reasonable and non-kludgey way of doing it.

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Those compressors draw only a few amps. Even 10awg wire is likely over kill.

What's the current draw, what's the cable run distance?

 

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The cable run is 19' and the circuit is protected by a 10 amp breaker.  I have not measured actual amperage when the fridge is running.

The breaker is as the installation manual and their cable sizing table recommends 8awg starting at 18' .   I bought the wire thinking;" Let's do it right" before checking whether the bleeding connectors were available.

Thanks all for the suggestions.  I'll update this thread when I've done something.

 

 

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Use a 4 screw terminal strip to get close, then 10 gauge to the spades.

I do this for a living.

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Sold! 

Thanks everyone for your help

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You're using way, way too much copper and getting some questionable advice.

You say the distance is 19 feet. Presuming that's actually 38' (11.5m) round trip and your compressor draws 4 Amps and your system voltage is 13V and you want a 3% loss then you can do fine with 14AWG wire.

10AWG will take you to 10A with that same 3% drop.

8AWG will take you to 16A.

 

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https://crimpsupply.com/connectors/12-10-to-8-ga-step-down-heat-shrink-butt-splice-terminals.html

2 of the above.  

If the run is as long as you listed It could be getting installed with 10/2 flat sheathed cable run the whole way(assuming Moonduster's note on expected power consumption for the unit is correct, and fused @ 10 amps it probably is).    However if it were my own boat and I happened to have 8ga in my hand and would have to run back to the shop to grab a spool of 10, then I'd just use two of those step down connectors and a short 10Ga bit on the end, making sure to secure it both sides of the step down, and leaving it long enough to let the wire flex(not a 2" stub, say 8" or so).  The fuse is still sufficient to protect the 10ga wire.  

While a terminal strip is technically correct, but not my preference when it's not required.  If it was a circuit you often changed things on, or you you were running a bunch of circuits all at once,  or you had multiple loads to with a single feed(low power draw LED lights for example) then definitely.  For a single system that is not likely to be changed often(fridge), you have now 4 additional mechanical fasteners involved(and exposed) and an extra thing to buy and install, adding more failure points. 

The manufacturer should list the exact power draw in the info on the unit, I find this chart is the nicest for for a quick reference, the colour coding makes it fast to use when you need to double check something.   It could be the manufacturer was expecting you not to double the length and was trying to avoid problems by specifying the cable size based on distance from breaker panel/ground to the fridge in which case the 18' 8ga specification would be correct.  

 

DC_wire_selection_chartlg.jpg

 

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Put the strip in a water tight carlon box, and be done with it ffs. That way when you call me to fix it when the module dies, or you stab the evap plate with a screwdriver, and I tell you to bring it to my shop for repair, you just unwire it cleanly, rather than cut the wires and have to deal with that.

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