Is your board being directly connected to AC power distribution of a 
     building?  If so, you'll have to make sure that it conforms to the NEC 
     (National Electrical Code).  This is where I have a problem with IPC 
     specification of trace construction.
     
     The NEC  rates 14 gauge wire for 20 amps and 10 gauge wire for 35 
     amps.  Since this is for solid wire, 14 gauge wire has a 
     cross-sectional area of 3227 square mils, 10 gauge wire has 8156 
     square mils.  If your 2oz. copper is 2.8 mils thick, then your 
     corresponding widths are 1.2 inches and 2.9 inches!!!
     
     Cross-sectional areas that are specified by the IPC as opposed to the 
     above procedure can lead to a difference in areas of up to of 5 TIMES.
     
     Someone have an answer for this?
     
     Doug McKean
     ADC Video Systems
     [log in to unmask]


______________________________ Reply Separator _________________________________
Subject: Conductor widths
Author:  [log in to unmask] at internet-mail
Date:    4/10/96 9:54 AM


Help,
     
 We are laying out a power distribution board. We have current
requirement of 35 amps and 15 amps. Our design is using 2oz copper, 
2 layers, and 20 degrees temperature rise.
     
 I am not sure of the conductor width required for both 35 & 15 amps.
Can anyone help answer this question?
     
     
     
Any help would be appreciated....
     
     
Ray.....
     
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    Ray McKinnon   Email: [log in to unmask]                                      
     
     
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