steelerdude
Member
- Location
- washington
What is the max amperage for a half inch (emt) conduit? You can get 3 # 12's so is the answer 20?
thank you
thank you
half inch condit
- Thread starter steelerdude
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- New Jersey
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- Journeyman Electrician
Is this a test question?
Welcome to the Forum.
Welcome to the Forum.
steelerdude
Member
- Location
- washington
yes and the instructor said it was 30
If it is (and not regarding ground fault current capabilities), I'm wondering how the test writer got qualified...:?
Doh!!!!! Thanks Gus, I think you have the answer.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
Roger
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I want to take this opportunity to mess with you.
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? :?
Ahh, but you didn't read note 7 in "The Notes to Tables" in Chapter 9I want to take this opportunity to mess with you.
I don't know either.
Roger
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
?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.
You can fit 3 # 8's in 1/2" emt. So by that 55 amps
K8MHZ
Senior Member
- Occupation
- Electrician
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.
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.
could be 22,000 amps, maybe more.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
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:Ahh, but you didn't read note 7 in "The Notes to Tables" in Chapter 9
Roger
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I still don't understand why a less fill will change anything in Reason 2.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
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.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
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
Senior Member
- Occupation
- Electrician
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.
....length was not given, what % fill are you basing your reply on?
table 430.72(B)
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