Correlating Ingress Protection (IP) and Explosion Protection (EP)

Complicated area mate. Your best bet is to google DSEAR (Dangerous Substances and Explosive Atmospheres), these are the regulations we have to comply to. You can get some good guidance. It sounds like you need to rate you equipment into zones, thats the easy part.

Thanks for your response, mate. I too agree with you that they are regulations & we have to comply. But I strongly believe there should be a correlation as it seems quite logical. Let us discuss on the following example (Pl correct me if I'm wrong)

For example, let us consider an example of an electrical equipment with explosion protection Ex d and ingress protection IP20. As we know, IP20 rating means the equipment is protected against ingress of solid objects of size of 12.5mm & above and not protected against water ingress. Not protected against water ingress can be considered as not protected against ingress of gas! (i.e. if water can go in, why not gas can go in?!) If gas can go into an electrical equipment, ultimately the probability for explosion exists.

So, the conclusion is IP20 is not sufficient for an Ex d rated electrical equipment! The question on minimum IP rating for an Ex certified equipment and existence of a correlation between Ex & IP ratings arises here.

Can you please clarify on the subject as I'm confused?

Exp proof is not necessarily water proof. Before we came up with the USA NEMA 4/7 rating all we had was NEMA 7 which is an indoor rating. Many NEMA 7 devices installed on outdoor switchracks invariably had water entry problems. Exp proof means that the explosion is contained within the enclosure, hence the wide flanges on that type of equipment. The idea is that the wide flanges would provide a flame path to adequately vent the explosion but that the flame would be sufficiently "cooled" by the time it got to the outside of the enclosure so as not to propagate the explosion to gases outside of the enclosure. Or at least that's the theory.

Clear as mud right?

Dear Guest,

Yes, I understand/got your point. Thanks for the explanation. But, still I want to know whether there is any minimum IP rating requirements for an Ex certified electrical equipment.

Can you clear my doubt, please?

EX d has no protection against gas ingress. It is designed to keep the eventual explosion inside the box and to limit the rise in temperature on the outside.

To release the pressure due to an internal explosion, they have holes that let the gases cool before they reach the outside of the box.

"So, the conclusion is IP20 is not sufficient for an Ex d rated electrical equipment! "

Wrong way round. Ex d rated equipment will have an IP rating typically of 55 or greater. Just because a piece of equipment has a high IP rating does not make it Ex d. For example, IP68 equipment need not be Ex d rated, as the flame path may be too short and the case not substantial enough to withstand and contain an internal explosion.

Ex i equipment need not have an IP rating; provided they are fed from an approved barrier, two bare conductors forming a switch would be acceptable as "simple apparatus".

Ex e would typically have an IP rating of 55, though it is not a requirement.

Ex o and Ex q, well there one goes...

Never try to apply logic to regulations. Regulations are completly independant of logic.

This is not completely true.

But if you read an actual regulation you see only the result of logics: the logics are in the history and preliminary work.

But as stated before: at one moment we invented the accountant (we are still looking for the engineer who did this) and the un-logical exceptions entered the system.

There is no correlation between IP and EX, for this the NEMA classification is better: an un-logical list. If you find a new way that is not in the list and you prove the usefulness they just add it. With the IP system you can't distinct it.

Refer for more details Electrical Engineering

Ingress Protection (IP) ratings are developed by the European Committee for Electro Technical Standardization (CENELEC) (NEMA IEC 60529 Degrees of Protection Provided by Enclosures - IP Code), specifying the environmental protection the enclosure provides.

The IP rating normally has two (or three) numbers:

1. Protection from solid objects or materials
2. Protection from liquids (water)
3. Protection against mechanical impacts (commonly omitted, the third number is not a part of IEC 60529)

Example - IP Rating

With the IP rating IP 54, 5 describes the level of protection from solid objects and 4 describes the level of protection from liquids.

An "X" can used for one of the digits if there is only one class of protection, i.e. IPX1 which addresses protection against vertically falling drops of water e.g. condensation..

IP First number - Protection against solid objects

IP Second number - Protection against liquids

IP Third number - Protection against mechanical impacts (commonly omitted, the third number is not a part of IEC 60529)