electrical risers 2

[stevemechanical]

I'm trying to determine if i need to upgrade the electrical riser to a 6th floor apartment in NYC.
The existing service is 160 amps 208v/1ph.
My service evaluation of the new proposed loads according to NEC 2002 article 220, section 220.31 (ac equip, appliances, receptacles & lighting) is 150 amps.

Do I consider a 25% safety factor (and upgrade the riser) or is that built into the NEC calcs?

 

[rbulsara]

NEC (and NYCEC too i am sure) requires condcutors to be sized for 125% of 'calcualted' loads. So it is not built into the calcs.

Your safety margin or room for growth is on top of it. Alwyas allow ample growth factor in your serice sizing, so that some one does have to upgrade again what you are doing.

Do not forget to check for voltage drops.

Side question: 208V single phase? you mean 208/120V, 3 wire plus ground? You better get help of a competent electrical engineer....

 

[stevemechanical]

Rbulsara
Thank you for your post. Is there a section in the NEC that calls for sizing risers at 125% of calculated loads?
Thank you in advance.
Steven

 

[rbulsara]

yes...Articles 220 and 230 also see 240


Don't recall exact paragraph

NYCEC has some more stringet requirements than NEC..please check that too..

Good luck..

 

[RonShap]

If these are considered "service entrance conductors", they get sized at 100% of non-continuous load plus 125% of continuous load. Consider that there are few continuous loads in an apartment. See article 230.42(A)(1).
NYC now follows 2002 NEC with amendments.

http://www.nyc.gov/html/dob/pdf/sec4a_ll_81_2003.pdf