Fusing a winch

[dwh]

2 AWG wire is good for 450A max for 48" runs

Sweet. So with a 500a fuse, the wire will protect the fuse.

But actually, that chart says "Total System Length" at the very top. So a 48" total system length would be a 24" run. For a run of 48", the total system length would be 96" and according to that chart, #2 would be good for 200 amps.



But technically, my question wasn't, "What's it good for?" - my question was, "What's it rated at?"

According to the National Electrical Code, Table 310.15(B)(16), 2 gauge AWG is rated between 95 and 130 amps depending on insulation type and temperature.

Anyone can make up their own chart, and many do. Those are NOT official wire ratings.

If I were using welding cable and wanted to ignore the NEC ratings, I'd go with welding ratings. Here's a chart from Lincoln:

http://www.lincolnelectric.com/en-u...ges/selecting-proper-size-welding-cables.aspx


[Note that duty cycle plays a part in how welding cable is rated.]


Personally, if I wanted to serve a load protected by a 450a or 500a fuse, I'd go with 2/0 (two-ought) welding cable, not #2. Unless I expected to have a 100% duty cycle, in which case I'd bump it up to 3/0.

 

[dwh]

Also, in the fine print of that SVC chart, they only allow for a very little voltage drop. As voltage drops, current increases, and a winch under full load could drop the system voltage quite a lot. Even if it only dropped the voltage 10%, that would still be a 10% increase in current - so a 400a load, with a 10% voltage drop could actually be pulling 440a through the wire.

 

[verdesardog]

Wire rating charts are fine for normal current carrying capability but a fuse is not the same as a wire. A 500A fuse will blow way before even a #2 wire will melt the insulation....And installing a fuse will increase the total resistance of the circuit, consider the connections and the fuse has more resistance than wire, it is designed to get hot and melt, can't do that with out resistance.

If you are concerned about safety a heavy duty switch or power pole type disconnect would be better but not automatic like a fuse.

 

[outofrshell]

That is the same fuse & holder that I am using for the #2 welding cable that goes to the rear of my Trooper (about 15 Ft.) where there is another plug in for the winch. I am not a real techy guy so I just use what I know works, I have winched my Trooper backward out a very deep snow drift and experienced no problems with any of the components of the system. The reason I wanted a fuse versus a switch was that I wanted some degree of protection for the cable going to the rear. Dave

 

[jkosten]

Hmmmm... while there is no direct down side to a fuse, I prefer to run oversize cables (less voltage drop) through a battery disconnect switch so when not in use it will not be "live".

Blue Sea systems make some sweet battery accessories btw.

sent from my pocket...

 

[brushogger]

My next test is to monitor the voltage drop under load. I'm going to have a camera on the scangauge for the system voltage and another on a voltmeter at the winch. I figure it's safer than having my big ol' head stuck down next to an operating winch. I'll just video it running under load. I sure wish I had a way to measure the current. I have an a amp meter for AC that's big enough. I doesn't have a DC setting though. My ammeter is an old Amprobe. As I understand it, it would need to a more modern one with a Hall effect sensor to accurately measure DC.

 

[dwh]

I've got an old Amprobe RS-3A model. Bought it new in the 80's. Mine has all the accessories as well.

Next time I buy a new amp meter (if I ever do...), I'll buy one that can do AC/DC and also do a sample and hold of inrush current. Sampling inrush is something that I've wanted to do quite a few times, and never owned a meter that'd do it. Always ended up borrowing one. Then of course, when I don't actually need it at the moment, I never get around to buying one for myself.

There's some decent looking AC/DC meters with inrush on Amazon for under 100 bucks.

 

[slomatt]

Small world! I just fused my winch with the same fuse and fuse block last month. I haven't had an opportunity to use the winch since then, but if the fuse is an issue it is easy to move the +12 lead from the winch to the un-fused post on the block.

- Matt

 

[brushogger]

The easy bypass was one of the things I liked about it too.

 

[flyingwil]

Small world! I just fused my winch with the same fuse and fuse block last month. I haven't had an opportunity to use the winch since then, but if the fuse is an issue it is easy to move the +12 lead from the winch to the un-fused post on the block.
- Matt

Nicely done. I like the thought process for failure.

 

[Brewtus]

Has anyone looked into a secondary power distribution box with circuit breakers rather than fuses? Then you could run lights, winch, inverter, etc. etc. etc. without having to worry about carrying extra fuses all from the same spot. Just like you have a breaker panel at home.

I've looked around a little bit to find DC circuit breakers, but have only found ones that go up to 150A 12v for auto applications. I suppose that you could get really big industrial breakers, but those are typically for high voltage applications, so their amperage ratings go out the window and may not translate to a low voltage system by simply multiplying by the ratio of voltages. Especially if they're thermal breakers rather than magnetic. Perhaps running some experiments with cheap thermal AC breakers like you would find in your house in a DC circuit would let you select say maybe a 50 amp 110v AC (5500 watts) breaker that would trip at 458A 12v DC (5500 watts)?

 

[eggman918]

You might try a marine supply house for higher amperage DC stuff.

 

[Borrego60]

Look at Eby.

 

[Brewtus]

Brushogger, did you order those through Del City? I'm rather leery of ordering things from websites I don't know well, and I can't find anyone else locally that can get them.

 

[65BAJA]

I've ordered from bestboatwire.com quite a lot and they have always shipped fast. The one time I did have an issue with a package busted up by USPS they reshipped the same day.