McIntosh 10+ year member
Senior VIP Member
I thought I'd ask them how they rate their wire. Talk about a bunch of BS responses. Can you say backpaddle or talking in circles?
My initial inquiry:
I notice you rate your 1/0 power cable @300 amps. The National Electrical Code lists the best insulated 1/0 @260 amps in free air at 86 degrees F ambient temperature. Underhood, undercarpet etc is certainly not free-air, let alone 86 degrees F ambient temperature. What type of insulation do you use to achieve this rating? I'm sure UL (or another testing agency) will back up your claims as it surely has been tested to perform as claimed. I plan to install a 300 amp service on my house. The code says I need 300MCM wire to carry this much current, if I could use your 1/0 I could save a LOT of money in wire and conduit. Please let me knu.
Response:
Does the NEC take in account the length the cable is being run? If its a commercial or residential application, most likely not. The 12V industry is completely different. In a car you KNOW the load on the system and the length it will be running, not the so much in other fields. 1/0 can handle a lot more then 300A at a 20' length. This cable is not designed to be used to service your home.
Bill
My next query:
Bill,
Thanks for your prompt reply. The NEC certainly does not take into account wire length as it has nothing to do with ampacity (only voltage drop, which is certainly addressed). Commercial, residential, and automotive amperes are the same. No 1/0 I know of is rated for 300 amps whether its 2' or 2000'. You never really KNOW the load, that's why cable is rated for a certain maximum. Anything above the manufacturer's stated maximum ampacity shouldn't be exceeded. My service runs would be far less than 20' in any event (more like 5' actually). Its the matter of changing the conduit (removing meter socket, etc) to accomodate the larger wire the code says I need that I'm trying to avoid. If you're wire is good for "a lot more than" 300 amps at 20' length, it certainly should be good for 300 amps at 5' length, no? I would certainly install a 300 amp main breaker to ensure your recommendations are not exceeded.
response:
In 12V you DO know the load and you DO know the length, that's where car circuits differ from anything in the construction business. Using the resistance of the conductor you can determine what the voltage loss will be at said length and current load. By knowing these you can determine the maximum capacity of the cable within the application. Yes 5' of 1/0 cable in a car would probably handle in excess of 800A and not have an issue. In fact 5' of 1/0 at 800A has nearly the same loss as 20' of 1/0 with a 300A load. See the calculator at the bottom of the page. We do not claim this cable to be rated for use in construction applications
http://www.powerstream.com/Wire_Size.htm
Bill
My next query:
Bill,
Once again thank you for your reply. You seem to be implying that with voltage drop there is a corresponding current drop. I certainly agree that all conductors have a certain voltage drop, but the current going in one end exactly equals the current coming out the other end. This is true regardless of length. The current is the same at every point along the wire. The heat generated by that current flow is also exactly the same along it's entire length. There is no difference in a wire's ampacity whether it's 2' or 200' long. The ampacity table you linked to lists 0 cable's ampacity as 150 amps. There is no mention of adjusting ampacity according to the wire's length. Exactly how are you arriving at your ampacity claims?
I expect no further responses from Knu. They are selling snake oil to uninformed people. He sent a link that clearly states 1/0 is rated for 150 amps then claims it's good for "in excess of 800 amps"! It's obvious to me where these rampant misconceptions come from on this site. The unscrupulous manufacturers are feeding you this BS. He wouldn't commit to my feeding my house with it (with a 300Amp breaker) but knows for sure it can handle a known 800 amp load. Makes sense to me. Reputable company? I think not.
My initial inquiry:
I notice you rate your 1/0 power cable @300 amps. The National Electrical Code lists the best insulated 1/0 @260 amps in free air at 86 degrees F ambient temperature. Underhood, undercarpet etc is certainly not free-air, let alone 86 degrees F ambient temperature. What type of insulation do you use to achieve this rating? I'm sure UL (or another testing agency) will back up your claims as it surely has been tested to perform as claimed. I plan to install a 300 amp service on my house. The code says I need 300MCM wire to carry this much current, if I could use your 1/0 I could save a LOT of money in wire and conduit. Please let me knu.
Response:
Does the NEC take in account the length the cable is being run? If its a commercial or residential application, most likely not. The 12V industry is completely different. In a car you KNOW the load on the system and the length it will be running, not the so much in other fields. 1/0 can handle a lot more then 300A at a 20' length. This cable is not designed to be used to service your home.
Bill
My next query:
Bill,
Thanks for your prompt reply. The NEC certainly does not take into account wire length as it has nothing to do with ampacity (only voltage drop, which is certainly addressed). Commercial, residential, and automotive amperes are the same. No 1/0 I know of is rated for 300 amps whether its 2' or 2000'. You never really KNOW the load, that's why cable is rated for a certain maximum. Anything above the manufacturer's stated maximum ampacity shouldn't be exceeded. My service runs would be far less than 20' in any event (more like 5' actually). Its the matter of changing the conduit (removing meter socket, etc) to accomodate the larger wire the code says I need that I'm trying to avoid. If you're wire is good for "a lot more than" 300 amps at 20' length, it certainly should be good for 300 amps at 5' length, no? I would certainly install a 300 amp main breaker to ensure your recommendations are not exceeded.
response:
In 12V you DO know the load and you DO know the length, that's where car circuits differ from anything in the construction business. Using the resistance of the conductor you can determine what the voltage loss will be at said length and current load. By knowing these you can determine the maximum capacity of the cable within the application. Yes 5' of 1/0 cable in a car would probably handle in excess of 800A and not have an issue. In fact 5' of 1/0 at 800A has nearly the same loss as 20' of 1/0 with a 300A load. See the calculator at the bottom of the page. We do not claim this cable to be rated for use in construction applications
http://www.powerstream.com/Wire_Size.htm
Bill
My next query:
Bill,
Once again thank you for your reply. You seem to be implying that with voltage drop there is a corresponding current drop. I certainly agree that all conductors have a certain voltage drop, but the current going in one end exactly equals the current coming out the other end. This is true regardless of length. The current is the same at every point along the wire. The heat generated by that current flow is also exactly the same along it's entire length. There is no difference in a wire's ampacity whether it's 2' or 200' long. The ampacity table you linked to lists 0 cable's ampacity as 150 amps. There is no mention of adjusting ampacity according to the wire's length. Exactly how are you arriving at your ampacity claims?
I expect no further responses from Knu. They are selling snake oil to uninformed people. He sent a link that clearly states 1/0 is rated for 150 amps then claims it's good for "in excess of 800 amps"! It's obvious to me where these rampant misconceptions come from on this site. The unscrupulous manufacturers are feeding you this BS. He wouldn't commit to my feeding my house with it (with a 300Amp breaker) but knows for sure it can handle a known 800 amp load. Makes sense to me. Reputable company? I think not.
