half inch condit

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roger

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The question doesn't make sense 1/2" EMT could have two number 6 THWN conductors in it so, if it were feeding a motor it could contain a circuit protected at over 100 amps.

Roger
 

augie47

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a 4" piece of 1/2" EMT is not sufficient diameter to fit in a 60 amp fuse clip, so it's obviously limited to 30 amps :D. The instructor apparently has performed HVAC work.
 

roger

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a 4" piece of 1/2" EMT is not sufficient diameter to fit in a 60 amp fuse clip, so it's obviously limited to 30 amps :D. The instructor apparently has performed HVAC work.
Doh!!!!! Thanks Gus, I think you have the answer. :D:D:D

Roger
 

Dennis Alwon

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The question doesn't make sense 1/2" EMT could have two number 6 THWN conductors in it so, if it were feeding a motor it could contain a circuit protected at over 100 amps.

Roger

I want to take this opportunity to mess with you. :D 1/2" emt with 2 wires can only be loaded 31% so it is .094 #6 is .0507. But I do get your drift.:happyyes:

Now the real reason I am writing this is to ask why 2 wires requires less fill. Is it for the potential that a third wire may be needed? :?
 

roger

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I want to take this opportunity to mess with you. :D 1/2" emt with 2 wires can only be loaded 31% so it is .094 #6 is .0507.
Ahh, but you didn't read note 7 in "The Notes to Tables" in Chapter 9 :)
Now the real reason I am writing this is to ask why 2 wires requires less fill. Is it for the potential that a third wire may be needed? :?
I don't know either.

Roger
 

jim dungar

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Now the real reason I am writing this is to ask why 2 wires requires less fill. Is it for the potential that a third wire may be needed? :?

?Reason #1? Ease of pulling, less damage to conducotrs. three conductors usually results in a 'rounder' bundle rather than the flat bundle of two wires.

?Reason#2? Capacitive coupling and cancellation of magnetic forces. Two conductors could possibly lay completely parallel against each creating a large capacitor. Three or more conductors will tend to twist and overlap in a random manner negating the capacitive effect.
 

K8MHZ

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?Reason #1? three conductors usually results in a 'rounder' bundle rather than the flat bundle of two wires.

You are on the right track. Two conductors take up more space per conductor than any other number in a round pipe.. One is perfectly round, (the best), two is almost perfectly oval (the worst) and three and up start taking up space like a round conductor again.
 

acrwc10

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I would say the MAX amps that you could run through a 1/2'' EMT is only limited by the avalible fault current from the transformer. it's not for a very long time, maybe a half cycle, but it would be the MAX amps. :angel:

could be 22,000 amps, maybe more.
 

Dennis Alwon

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Ahh, but you didn't read note 7 in "The Notes to Tables" in Chapter 9 :) I don't know either.

Roger
I knew about Note 7 but did the math in my head and I forgot about Note 7. That's what I get for trying to be a smart arse. :lol:
 

Dennis Alwon

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?Reason #1? Ease of pulling, less damage to conducotrs. three conductors usually results in a 'rounder' bundle rather than the flat bundle of two wires.

?Reason#2? Capacitive coupling and cancellation of magnetic forces. Two conductors could possibly lay completely parallel against each creating a large capacitor. Three or more conductors will tend to twist and overlap in a random manner negating the capacitive effect.
I still don't understand why a less fill will change anything in Reason 2.
 

Dennis Alwon

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What is the max amperage for a half inch (emt) conduit? You can get 3 # 12's so is the answer 20?


thank you

IMO, the way this question is worded it is talking about the conduit used as a conductor. If you knew the resistivity of the conduit you could then figure what ampacity it is good for. Now what the instructor had in mind is anybodies guess.
 

jim dungar

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I still don't understand why a less fill will change anything in Reason 2.

Taking less time to think than to type.
induction heating from improper magnetic field cancellation? Choking effect during fault conditions?
No real idea, but these are things I would look into.
 

K8MHZ

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IMO, the way this question is worded it is talking about the conduit used as a conductor. If you knew the resistivity of the conduit you could then figure what ampacity it is good for. Now what the instructor had in mind is anybodies guess.

I don't know where, but I did see a chart about conduit concerning how much fault current it could handle. I think that is what the question is centered around.
 

jusme123

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The question doesn't make sense 1/2" EMT could have two number 6 THWN conductors in it so, if it were feeding a motor it could contain a circuit protected at over 100 amps.

Roger

....length was not given, what % fill are you basing your reply on?
 
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