Question on article 440.22 (a)

[Davidson Electrical]

440.22 (a) gives me the impression that we aren't supposed to use 225% to size the overcurrent protection device unless 175% is not sufficient for the starting current. However, in Mike holts 2014 electrical exam prep book all of the protection sizing calculation examples for motor compressors use 225%.. so what am I missing?? I know I can use the nameplate most of the time and I Probably won't see this on my upcoming test but I would really like to know thanks!!

 

[Smart $]

Welcome. :thumbsup:

If the question asks for the maximum overcurrent protection rating, using 225% is correct.

 

[Dennis Alwon]

Smart-- go to sleep---:lol:

Seriously, when a question came up a long time ago you stated we should always use the rule not the exception when answering a question. Is this not the same?

 

[Davidson Electrical]

Welcome. :thumbsup:

If the question asks for the maximum overcurrent protection rating, using 225% is correct.

The questions ask for the required protection device.

 

[Smart $]

Smart-- go to sleep---:lol:

Seriously, when a question came up a long time ago you stated we should always use the rule not the exception when answering a question. Is this not the same?

:huh:

In this case, 225% isn't written as an exception to that section. It is actually stated right in the section. Test question authors will likely consider that fair game.

 

[Davidson Electrical]

Found it

Found it

Found some other calculations in the same book using 1.75 and 2.25 if that doesn't work.. so guess that is right. Those examples just confused me..

 

[kwired]

Poor question as worded I would say. Without "maximum" being in the wording anything under 226% is an acceptable level code wise.