Taps don't need OCPD

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kid_stevens

kid_stevens

Senior Member
Location
Albuquerque, NM
The question was: You have an 800 Amp busyway and you pull a tap for 200 amps from it. At what length tap are you required to have an OCPD?

Beat my head into the screen for 8 minutes on this one and never found it in the 2005 NEC. I was one point from passing.
 
celtic

celtic

Senior Member
Location
NJ
chris kennedy said:
So what is the answer to kids question? 10',25'?
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We don't give answers...just references.
You check the reference and tell us the answer.
We then tell you OK...or provide further reference.

:D
 
celtic

celtic

Senior Member
Location
NJ
chris kennedy said:
Then I want my money back.
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Not a problem....just send us your account numbers and SSN and we will refund your purchase price in full ;)


chris kennedy said:
Celtic I don't see that 240.21(B) is the right referance.(but I got nothing better)
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ok...why not?
 
eric stromberg

eric stromberg

Senior Member
Location
Texas
kid_stevens said:
The question was: You have an 800 Amp busyway and you pull a tap for 200 amps from it. At what length tap are you required to have an OCPD?

Beat my head into the screen for 8 minutes on this one and never found it in the 2005 NEC. I was one point from passing.
Click to expand...

240.21 is the right reference. Here's an executive summary.
Taps 10 Feet or less. The tap must be rated for 1/10 the Feeder OCPD
Taps over 10 but 25 or less. The tap must be rated for 1/3 the Feeder OCPD
Taps outdoors have no length limit
Taps in high bay manufacturing must be 1/3 but they can only be 75 feet long

MCC vertical buses fall under the 10' rule. This is why you can have an MCC with a 2000 Amp horizontal bus that connects to 300 Amp vertical buses.

But if this is an exam question, it might be a trick question. Taps are never required to have an OCPD. That's the whole point. They are considered to be protected by the downstream OCPD.
 
kid_stevens

kid_stevens

Senior Member
Location
Albuquerque, NM
chris kennedy said:
Thats a reduction in bussway ampacity. Not a tap.
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It also gives Maximum length.

eric stromberg said:
But if this is an exam question, it might be a trick question. Taps are never required to have an OCPD. That's the whole point. They are considered to be protected by the downstream OCPD.
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The test gave 4 lengths none that matched 240.21 one number was 50ft so that matched the 368.17(B)

So close and so far away. I let my personal Masters drop because I was working for corporations on Telecomm sites and large buildings. So now I am paying the price.
 
eric stromberg

eric stromberg

Senior Member
Location
Texas
kid_stevens said:
So close and so far away. I let my personal Masters drop because I was working for corporations on Telecomm sites and large buildings. So now I am paying the price.
Click to expand...

I teach exam preparation classes. At the end of each class i used to say "Good Luck" to the students. Then i watched an Arnold Schwarzenegger movie where he was getting ready to go to the FDA for something (I don't remember the name of the movie, but i think it was the one where he was pregnant) and someone wished him "Good Luck." As he was closing his brief case he retorted, as only Arnold could do, "Luck is for the ill-prepared." Since then i haven't known what to say at the end of class. But the fact remains that luck is still involved. In any exam there are badly worded questions that have multiple correct answers.

Anyway, good luck, or, best wishes, or better yet...

Live long and Prosper!
 
S

steveng

Senior Member
Location
Texas
eric, where do you teach class?

eric, where do you teach class?

eric, do you teach in the houston area?
what exam materials would you suggest for the j-men exam?
any info would be humbly appreciated..:grin:
 
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