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Spt2 wire


JDH
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Newbe here,

How to you determine how long of Spt2 wire you can use before you change over to a heavier extension cord. Can I use as long as 100' of spt2 for less than 8amps.Frist year with LOR and I can't wait to get the lights on. Thank you for your help.

John in Ill.

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yup, i did. get yourself one of those kill-a-watt meters, to be sure you don't go over the 80% rule. i've got several that are over the 100' mark.

Can you expand on that a bit as far as using the kill-a-watt as it relates to cord length and the 80% rule? Maybe I'm just not understanding your approach.

,

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Gary,

All wire has resistance. There comes a point where the resistance of the wire at near its rated current carrying capacity, there will be a voltage drop. We call it the IR drop. What big Joe does that has worked for him is something like this. 18 ga wire can carry 8 amps (not all 18ga wire created equally some less current, but that it is a different topic.) So 80% of that is like 6.25 amps or there about. So, as long as his load draws less than 6.25 amps he can go out to 100' of wire. But if he needs 8 amps then he should go to a lower gage number like 16 ga which is a large wire.

There did that make things as clear as mud?

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Gary,

All wire has resistance. There comes a point where the resistance of the wire at near its rated current carrying capacity, there will be a voltage drop. We call it the IR drop. What big Joe does that has worked for him is something like this. 18 ga wire can carry 8 amps (not all 18ga wire created equally some less current, but that it is a different topic.) So 80% of that is like 6.25 amps or there about. So, as long as his load draws less than 6.25 amps he can go out to 100' of wire. But if he needs 8 amps then he should go to a lower gage number like 16 ga which is a large wire.

There did that make things as clear as mud?

Max, I was expecting Joe to respond, and I doI understand basic electricity, but thanks for the dumbed-down explanation. There will always be voltage drop in any length of wire, won't waste time debating the first few sentences and your explanation.

While uising the kill-a-watt to verify whether his IR drop is beyond what he considers the limit is fine, the channel limit (8A) is also a determining factor, so before going to larger gauge wire, as you mention in your explanation, I'd be looking at spreading the load across more channels, but thats another (separate) design issue altogether and has nothing to do with the original question.

My point in asking is its not the way I would do it (not saying its incorrect), so was curious as to the approach and thought process.

Edited by GaryM
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Thanks for the Duh, Gary. Forget myself sometimes with the unwashed masses, esp at this time of year. Thanks for reminding me, that you are one that actually gets it. Suppose we will have to wait and see if my explanation is close to what Joe does.

Joe, was I close to getting it right?

BTW I was taught to build up from something that the person you are talking with and then move into the new material. Thats my M.O. Gary. Not meant to be dumbying down.

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Thanks Big Joe for replying.

Uh, was there a misunderstanding with me and you Gary. I just was rereading and hope you did not misunderstand. I was not including you in the "unwashed masses" Gary. I am referring to all of those who have shown up in the last month or so, asking all of the off of the wall questions. Ones who can barely plug a plug into the wall outlet. Anything above that is beyond them. The ones that think you just plug and it plays all on its own. You know the type. So, no, was not including you in that groups and sorry if you thought I was.

Edited by Max-Paul
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