Are current ratings BS?

[Buck 5,000+ posts]

Most companies rate their 1/0 at 300a.

My question is that rating at 12v? Or is it at a higher voltage?

This brings up another question. Does the amount of current a wire can carry vary depending on how low or high the voltage is? Say if a wire is rated at 300a @ 120v, would the current rating be less at 12v?

I think some of you might see what I'm getting at.

Click to read more...

 

[helotaxi 5,000+ posts]

Amperage rating is independent of voltage. The amperage rating is based on the amount of voltage drop and thus the amount of heat that will be generated within the wire.

 

[Buck 5,000+ posts]

Ok. So a 300 amp rating is going to be 300 amps no matter what voltage? Is there any tests that prove this? (Especially for car audio, like 12v vs. 16v)

 

[Magnus 10+ year member]

This is why I ALWAYS do two runs of 1/0 gauge when doing the big 3. Plus I use KLMX so lol.

 

[Louisiana_CRX 5,000+ posts]

 

[Buck 5,000+ posts]

Is that directed at me? I think it's a legit question.

 

[Louisiana_CRX 5,000+ posts]

you've been here long enough...you should already know the answer...i'd expect a question like that from a 10er

 

[Buck 5,000+ posts]

you've been here long enough...you should already know the answer...i'd expect a question like that from a 10er

Well somebody brought an interesting concept to my attention, I was seeing if it was correct or not. I've always known it to be 300 amps no matter the voltage.

If you want the real answer, I'm bored as hell and wanted something to talk about. Knowing this for sure just extends my car audio knowledge that much more...at least that's the way I look at. If I'm not sure about something, I ask about it.

 

[CHEMMINS 10+ year member]

I think the ratings are wrong. Unless they are testing a 1 ft piece. At 300 amps, the temperature of 1/0 is going to increase, causing the resistance to be less and less, until failure.

 

[Phoenix Risen 10+ year member]

starting like someone needs to get a 20ft piece of 1/0 and build something to test this out.

 

[CHEMMINS 10+ year member]

You volunteering?

 

[RAM_Designs 5,000+ posts]

I think the ratings are wrong. Unless they are testing a 1 ft piece. At 300 amps, the temperature of 1/0 is going to increase, causing the resistance to be less and less, until failure.

In a car audio application where you never see 100% power for more than a split second, I think it's a perfectly fine rating. That's why 1/0 welding cable is rated so much lower, because it has a solid amount of current being ran through it for extended periods of time...this just doesn't happen with car audio installs. So instead of being the one guy who rates his stuff based on continuous amperage, everyone kinda accepts that a 3kw amp(aka: 300 amp draw for simplicity's sake) can be safely ran in a daily system with a single run of 1/0.

If one company were to actually rate their 1/0 based on what kind of amperage it can continuously handle, the mainstream buyer who knows no better would never buy their product...kinda like rms vs max power figures.

 

[CHEMMINS 10+ year member]

Funny you say that though, because Iasca and engineers rate it for continuous use, but wire manufacturers rate for intermittent. Look at welding cable, they rate 300 amps on 1/0 as well. Which is very very wrong to do.

 

[Louisiana_CRX 5,000+ posts]

Well somebody brought an interesting concept to my attention, I was seeing if it was correct or not. I've always known it to be 300 amps no matter the voltage.
If you want the real answer, I'm bored as hell and wanted something to talk about. Knowing this for sure just extends my car audio knowledge that much more...at least that's the way I look at. If I'm not sure about something, I ask about it.

i'm always for building my poast count...so talk away....but i know you've seen diffrent 1/0 some will fill the connector some will barely fill a 4 ga connector...some is aluminum some is copper...some is copper coated aluminum...they rate them the same...common sense knows they arn't the same

 

[CHEMMINS 10+ year member]

True, but voltage is a concern really, cause 300amps at 12v is a lot different than 300 amps at say 600v. When they test these cables what is the testing voltage?