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Tag Archives: Educational

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
Categories Mechanical Engineering

What’s an IP rating?

Why should I care about enclosure conditions?

When starting any project that involves an enclosure the first questions that get asked are about ratings on the enclosure. There are a couple of different rating systems (i.e. UL, IP, NEMA) that need to be taken into account depending on device deployment; however, the first one that is going to be discussed is the Ingress Protection (IP) rating system.

The IP rating system is critical to discuss when taking on a project because it covers the use cases for the product and the potential hazards it will face. The majority of the time IP ratings are used to discuss how an enclosure will handle water in a given situation; however, the IP rating system covers any objects that intrude into the enclosure (i.e. dust, sand, oil).

As the IP rating increases the cost of an enclosure typically does as well because more care has to be taken when choosing materials for the enclosure as well as the sealing of the enclosure.

If this is not discussed at the beginning of a project this shortcoming in a discussion can lead to costly enclosure changes, device critical failure, and costly tooling changes to accommodate.

A great example of this topic being overlooked was an LED light I ran across from a startup years ago in Seattle, WA that had not discussed IP ratings at any point even though their product was made for outdoor/indoor use. When the device was implemented in the field the startup discovered a high failure rate reported by the customer. The issue was two-fold: 1) the farmers were spraying oil onto the fixtures when spraying the fields and 2) moths were getting through the fans then expiring within the case. Both of these caused the device to overheat and fail to cause the entire enclosure to be redesigned for issue accommodation.

What do the numbers mean?

All IP ratings follow the same formatting within the standard and it is important to get acquainted with them because they will mean a lot not only to engineers but to the customers that will buy the product. The rating always starts with the two letters IP followed by a 2 digit number, which contains the meaning. Each individual number has a separate meaning apart from one another.

The first number represents solid object protection for the enclosure and the second number indicates the level of protection against liquid infiltration.

#First Digit – SOLIDSSecond Digit – LIQUIDS
IPXXProtection unspecified (untested)Protection unspecified (untested)
IP54Protected from limited dust ingressProtected from water spray from any direction
IP55Protected from limited dust ingressProtected from low-pressure water jets from any direction
IP56Protected from limited dust ingressProtected from high-pressure water jets from any direction
IP57Protected from limited dust ingressProtected from immersion between 15 centimeters and 1 meter in depth
IP58Protected from limited dust ingressProtected from long term immersion up to a specified pressure
IP60Protected from total dust ingressNot protected from liquids
IP61Protected from total dust ingressProtected from condensation
IP62Protected from total dust ingressProtected from water spray less than 15 degrees from vertical
IP63Protected from total dust ingressProtected from water spray less than 60 degrees from vertical
IP64Protected from total dust ingressProtected from water spray from any direction
IP65Protected from total dust ingressProtected from low-pressure water jets from any direction
IP66Protected from total dust ingressProtected from high-pressure water jets from any direction
IP67Protected from total dust ingressProtected from immersion between 15 centimeters and 1 meter in depth
IP68Protected from total dust ingressProtected from long term immersion up to a specified pressure
IP69KProtected from total dust ingressProtected from steam-jet cleaning