Amps and Fusible Links

[jack orchard]

What are the max amps for wire size for 12VDC in auto applications (10GA, 12GA, 14GA, 16GA, 18GA?
If i had a 20 amp load on 10 GA wire how do i determine the size of a fusible link to protect it. An example of this would be a feed wire to a small fuse panel that is hot at all times.
Thanks to all for your time....jack

[Old Henry]

Use a fusible link 4 gauge sizes smaller than the wire that you want to protect. So, to protect a 10 gauge wire you'd use 14 guage fusible link.

From here: http://en.wikipedia.org/wiki/Fusible_link

Here's the chart for amp capacities of various gauges of wire at 12 volt DC:
http://www.offroaders.com/tech/12-vo...gauge-amps.htm

(You're right on running 20 amps through 10 gauge wire.)

Here's a chart for 6 volt if anyone is interested: http://www.flatheadv8.org/rumblest/electric.pdf

[wga]

Do not use a fuseable link under any circumstances, they cause all kinds of problems. The circuit breaker and fuses will react faster, so that your system does not smoke.
For higher amp loads use a circuit breaker, which can be sourced from NAPA.

If you are switching loads use a relay. http://www.the12volt.com/relays/relays.asp

[Old Henry]

Originally Posted by wga

Do not use a fuseable link under any circumstances, they cause all kinds of problems. The circuit breaker and fuses will react faster, so that your system does not smoke.

I agree. I have too many fuseable links on my 90's Dodge Van and they are a nightmare. When they burn out there's virtually no way to know where they are or which one has burned out. And to replace them once burned out? Nightmare like I said. Fuse or circuit breaker is the way to go.

[31chevy]

I agree with the don't use fusible link advice , use fuses or circuit breaker. My 2 cents.
Gary.

[jack orchard]

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Old Henry, wga, and 31Chevy:
Thank you for taking the time to respond to my questions. I will take your advice and use circuit breakers instead of fusible links.
I also learned that short runs of wire can carry 12VDC at a far greater amperage than i thought. For instance 10 feet of 18GA wire will carry 15 amps. I probably would not load that much on 18GA, would most likely use 14GA, but it is nice to know the limitations of each size of wire. Thanks again to all...jack

[Topsterguy]

I can understand not using fuseable links because they leave you screwed when they go, but what about inline fuses?......and if so what amperage would you use on the battery power 10 gauge wire?

[Drbrown]

As you've seen and Old Henry indicted, wire gauge and length determines its amperage carrying capacity - there are many tables on the internet to help. Fuse size should not exceed that rating. You can double check your installation by putting an amp gauge on a particular circuit and turning on all the devices it serves. General Rule of Thumb: Oversize the wire and under size the fuse.

Long-term: Just like ground wire connections, fuse blades/stub-ends and fuse holders tend to oxidize, thus increasing resistance/voltage drop and heat. Check and clean them from time to time to maximize performance.

[wga]

http://www.engineeringtoolbox.com/wi...ges-d_419.html

[gmc1941]

If your link is getting hot it could be poor contact on the link.