Automotive Jumper Cable Amperage Claims

[jerryg2112]

Can someone explain to me how a company can claim that their 16' 6 gauge wire jumper cables can handle 400 amps? I've been looking to buy or put together some jumper cables and have been reading about wire gauge and amperage. From what I found 6 gauge wire is rated at 55 / 65 / 75 amps @ 60/75/90 °C (and that is probably a short run not 16'). Are their claims based on a surge rating?

[shorod]

The 55/65/75 ratings are more for constant current carrying, and like you suspect, the 400 amp is a pulse surge. Hopefully they're taking in to account the melting point of the wire insulation, the ohm/ft resistance of the wire, and the rating of the clamps when determining that the cable assembly can handle 400 amps of current for some small amount of time. This is kind of like the portable jump start packs that have a 17 amp-hr battery but claim a 400 amp start current. The battery is capable of delivering 400 amps but for a very short amount of time.

-Rod

[carod]

I would go with a 4 gauge wire.