Rating of NEMA versus IP Boxes

There is often confusion about the various rating systems for the protection of equipment within an enclosure. We are often asked which system is best and how are they different? If the customer is in the US, are they better off buying NEMA boxes or one with an IP rating, or does it even matter? While there are no hard and fast answers to the question of which is best, we thought it might be helpful to provide a few details to help the customer navigate these systems.

IP, or ingress protection marking, is the International standard, typically used throughout the world and only recently gaining adherents in the US.  It is based on the IEC (International Electrotechnical Commission) standard 60529.  NEMA ratings were established by the National Electrical Manufacturers Association and take a somewhat different approach to designating protection levels than does the IP system. While there can be self-testing (and these are typically noted by phrases such as “designed to meet IPXX”), there are regulatory agencies such as UL for NEMA and TUV for IP that will perform and certify the tests for the various levels of protection. While there are charts that purport to show the relationship between and IP rating and a NEMA rating, the differences can be subtle yet important.

An IP ratings typically is a two digit number. The first digit stands for the level of solid particle protection while the second digit represents the level of liquid ingress protection. The levels for the solid particles range from 0 for no protection to 6 which is dust tight.  The second digit ranges from 0 (no protection) to 9.

The NEMA system uses one number to represent the level of protection although confusingly the higher the number does not necessarily represent increased security but rather different types of water resistance.

The other difference is that the tests performed to certify the ratings might be quite different although they produce a similar level of protection. For example, the spray test on a NEMA 4 box is 65 GPM of water from a 1 inch nozzle delivered from at least 10 feet away for 5 minutes. Some may suggest that NEMA 4 is the same as IP66, but the IP66 test is for 3 minutes instead of 5, 3 meters instead of 10 feet and with a slightly different sized nozzle. Although close, they are not the identical.

Below are the charts with a brief explanation of the protection levels and testing process. used to rate IP Boxes and NEMA Boxes.  As always, if you have any questions, never hesitate to contact the enclosure manufacturer for exact details and certifications.

IP protection explained.

number 1

2nd a

2nd b

2nd c

2nd d

NEMA ratings.

nema a

nema b

Let’s take a look at a NEMA 4 enclosure from our YouTube channel.

With so many box sizes available please contact Sales@Discount-Low-Voltage.com for a detailed quote.

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