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Tag Archives: Underwriters Laboratories

Categories Electrical

Wire Gauge and Current Limits

Wire gauge is a HUGE concern when developing proof of concepts (PoC); however, because of how the rapid iterations are done it normally doesn’t get enough attention during the entire assembly or testing. If proper diligence isn’t done wire gauge comes up when the assembled device is exhibiting “abnormal” behavior(s). This has become more prominent with the newly, more powerful ARM-based boards because of the higher power requirements across the board and with increased reliability needs in IoT when UPS get introduced.

I often find myself or my engineers looking up online AWG standards (often landing on the Wikipedia Chart or the PowerStream chart) for proper amp ratings when verify wiring or when doing a finalized wiring diagram for a project I wanted to provide a place where someone would be able to get a better understanding of some of the concepts of AWG or just a quick reference that saves a couple of minutes of “Googling”.

To start, AWG stands for the American Wire Gauge (AWG) system; often this is closely tied to the National Electric Code (NEC) or comes up with discussions of Underwriter Laboratories (UL) for any large appliances. This chart should just be used for rough gauging on “where to start”; often additional calculations have to be applied based on length of runs and application. 

Chassis Wiring and Power Transmission

An important wiring distinction that isn’t commonly understood well would be whether an item gets classified as either chassis wiring or power transmission wiring. If the wrong standards are applied it can lead to either “abnormal” behavior within the electronics as electronics hit caps or TOO much wiring and devices cannot be closed up properly.

Chassis wiring assumes each wire is routed separately, normally implying better airflow whereas power transmission wiring assumes the wires are bundled (e.g. conduit); chassis wiring normally assumes MUCH shorter runs that bring lower overall resistance(s).

As with every chart oddly found on the internet; this is just meant as a quick reference and not used as a bible.

AWGMaximum amps for chassis wiringMaximum amps forpower transmission
00283190
0245150
1211119
218194
315875
413560
511847
610137
78930
87324
96419
105515
114712
12419.3
13357.4
14325.9
15284.7
16223.7
17192.9
18162.3
19141.8
20111.5
2191.2
2270.92
234.70.729
243.50.577
252.70.457
262.20.361
271.70.288
281.40.226
291.20.182
300.860.142
310.70.113
320.530.091