quick question

[Papermaker85 5,000+ posts]

I skipped over alot, but just wanted to throw this out there. A guy I built a box for called me to see if I could come figure out why his sub wasn't playing anymore. Here's what the problem was. The amp was an sq2200@2ohm.

Sent from my Motorola 2950 Special Edition 3w

me too!

 

[Papermaker85 5,000+ posts]

**** im just trying to help them make a more informed decision. but these people refuse to even look at the FACT they have a basis for this. SMH its cool when htey have to trouble shoot ****** accesories and equpiment thats them..

like those ****** *** fuse holeders melting. Id bet it was becasue they useing copper brass nickel and alum through and thermanial expension and ampictly is terrible so the connection slowly get worse and worse and bam arcing and fire..

 

[keep_hope_alive Premium Member]

we use a PF of .9 or .8 the power factor is going to be .95 give or take.. but hte power factor isn't corrected in the amperage ratings.. the NEC code typicall rates there amperage ratings with a 75C and at 90 degrees ambient tempature. glad you pointed that out though becasue it can be a factor..

The 75 deg C and 90 deg C columns aren't ambient temperature, they are listed temperature rating of the wiring and terminations. Typically, set screws are 60 deg C and lugs are 75 deg C. Most THHN/THWN wiring these days is 90 deg. C. rated but you can't use the 90 deg. C. column due to the terminations.

Rich V.

 

[Papermaker85 5,000+ posts]

The 75 deg C and 90 deg C columns aren't ambient temperature, they are listed temperature rating of the wiring and terminations. Typically, set screws are 60 deg C and lugs are 75 deg C. Most THHN/THWN wiring these days is 90 deg. C. rated but you can't use the 90 deg. C. column due to the terminations.
Rich V.

yes i understand that Rich but as you know we also derate more as ambiant tempature rises. i always order/use UL rated 90' connnectors and thhn wire for all applications. Unless otherwise specificed.. while the car audio wire isnt rated I assume the worst of coniditions. that why you always find me recommending larger wire and good connections but i get shunned for it.

 

[Papermaker85 5,000+ posts]

Rich i know. but they also use a ambiant temp rating on top of that and its typically 86 degrees. the higher the ambiant temp the more you dertate.

Artical 310.15 B under wiring ampacity

http://mjobee.com/projects&news/nec%20art%20310.15.pdf

sorry for the double post..

 

[keep_hope_alive Premium Member]

For THHN, I figure an 82% multiplier for 60 deg. C copper for 100 deg. F.

Rich V.

 

[keep_hope_alive Premium Member]

But 310.16 doesn't apply to car audio. It is for 3 conductors in conduit in air.

Rich V.

 

[Papermaker85 5,000+ posts]

But 310.16 doesn't apply to car audio. It is for 3 conductors in conduit in air.
Rich V.

freeair ratings are listen on some sites.

 

[Papermaker85 5,000+ posts]

i just had to take another certification test. im forgetting some of the stuff i never use.. ******* code book is alot of ****!

 

[keep_hope_alive Premium Member]

freeair ratings are listen on some sites.

Agreed. I'm not saying we can't reference NEC, just that load factor (not power factor), termination rating, wire rating, UL Listing of the wire, and ambient temperature play a role in applying the tables, and we need to use the right table.

Sadly, you won't find ratings or UL Listings on most car audio products.

Rich V.