IP Code for Motor Enclosure

Hi John,

Let say, I want to install motor for driving a Fan in Battery Room.
Regarding with Classification Area in Oil&Gas Industries and some Process Safety requirement, the motor shall be Class I Zone 1 Group C T3 ATEX certified.

I am trying to looking in the vendor catalog and I find if the minimum IP suitable with this case is minimum IP 55 T3.
And other vendor state for zone 1, it shall be IP 65.

For me it's very debatable. If we back to the philosophy IP code, it will be intended for Solid object and water object.
I select IP 55 because minimum enclosure protection for Class I Zone 1 is IP 55 (regarding with vendor offering)and for Hazardous protection I selected Ex "d" for motor enclosure and Ex "e" for terminal box.

If some vendor come and offer me optional / modify product such IP 55 for enclosure and IP 41 for terminal box, for me it is make sense because its a indoor location as long as Ex "d" and Ex "e" can be proven.

My Question:
1. Is it possible to achieve IP 41 and Ex "e" in same terminal box?? Is it marketable??

2. Is it possible to put IP 55 Ex "d" T3 for motor enclosure and IP 41 Ex "e" T3 for Terminal box? Have any problem with ATEX,BASEEFA, UL, and any other notified body certification for explosive atmosphere??

A1, yes, provided it states so on the certificate.

A2, yes, provided it states so on the certificate.

However, if the terminal box is IP41, then the assembly won't achieve overall IP55. If IP55 is required, then select a different piece of equipment.

Remember also that the cabling and glanding need to be selected correctly too for the Ingress Protection number to be valid.

No special glanding is needed for Ex e.

I'm sorry, but I'm not qualified to give you advice on this.

I'd also point out that you cannot guarantee the qualifications of or the quality of advice from anyone else on this site. I'd advise you to contact the motor suppliers directly, and ask for written evidence that the items they are supplying are suitable of use in your application.

You are treading on dangerous ground - be careful.

For what it's worth, I believe there's little or no correlation between IP rating and Ex rating (but I could be wrong).

The ingress protection code will be the higher of the two in the case of a non-hazardous area device and will relate to the whole assembly. It is not possible to achieve Ex d protection at IP ratings lower than IP55.

In the case of non-hazardous area equipment, the IP rating of the installation will be the lowest of that provided by the motor, the termianl box and the gland, for obvious reasons.

In the case of a hazardous area device under Ex d, correctly selecting and installing Ex d glanding is as just as important as selecting the IP rating of the equipment and its connection box.

PWSlack & John,

So I can summaries, For Hazardous Area:

- It better to achieve Ex protection first and then IP-enclosure.

- It is possible to put different protection for "motor enclosure" and "terminal box".

I state like that because of some rule of thumbs said when we see the name plate of motor, let say IP 55 it means IP 55 for enclosure and IP 55 for terminal box as well.

My concern actually for certification. If I select IP 55 Ex "d" and IP 41 Ex "e" and then notification body will reject my product. When, let said ATEX, will conduct a test to give a ATEX certification, is it usually testing in one package (Motor + Terminal Box) or separate between "motor" and "terminal"??

<...It better to achieve Ex protection first and then IP-enclosure....>

Ex d withstands an internal explosion so that transmission of the flame to the surroundings is unlikely to occur. By definition, high IP rating numbers may be expected under Ex d, as concurrent with the explosion protection, mating surfaces are so tight that as well as flames getting out, water cannot get in readily. And that's why there are special requirments on glanding.

Ex e is a high construction stndard that makes the risk of sparking and hot spots unlikely. IP4x is entirely possible under Ex e; under Ex e there is no need to contain any explosion within the equipment, as the construction standard makes the explosion unlikely. And that's why there are no special requirements on glanding. However, one might expect minor water ingress into the Ex e terminal box under some circumstances.

<...It is possible to put different protection for "motor enclosure" and "terminal box"....>

Of course, though an IP43 Ex e terminal box won't achieve an IP55 rating requirement for the total package.

If the box were IP55 instead, then the whole assembly might be classified Ex d provided it is of suitable substance and construction, and that is why the certificate is of principal importance in selecting the equipment to match the requirement.

.........or it might be certified Ex de at IP55; under these circumstances it would not be necessary to use an Ex d gland for explosion protection in an Ex e terminal box, though the use of an Ex d gland will certainly achieve IP55.

http://en.wikipedia.org/wiki/Electrical_equipment_in_hazardous_areas#Multiple_Protection

Motor and terminal box are rated as one, both for Ex and IP. It would be a nonsense to do otherwise since the terminal box is part of the motor and located in the same area, and certifying bodies would not certify them seperately. What is on the nameplate applies to the whole unit, including terminal box (but pay attention to glanding, as PWSlack correctly highlights).

In fact, you could probably ignore the IP rating. The motor will be selected with the level of Ex protection according to the zone in which the equipment is located. As PWSlack also correctly points out, the IP rating will not be less than IP55. If the equipment is in a zone requiring more than this (eg IP68 for submerged) then it is less likely to be a hazardous area.

.....although submersible pumps would not be used in liquids with a potentially explosive vapour in zone 0, as the area classification would not permit it. Wet wells in sewage pumping stations are usually classed Zone 1.

Atex ratings and environmental ratings are generally separate issues, apart from Exe certification which relies on the containment to block the hazard from reaching the possible internal ignition sources. Exd motors tend to be IP-54 or IP-55, they are not sealed as the flamepath allows controlled emissions (cooled) to the external atmoshere. If you require higher enviromental protection on an Exd motor you need to look at dual certification such as an Exde, which means the motor is flameproof but the connection box is IP-Rated.

My simple answer is that IP55 is code for motor enclosures which are sealed so that even water from the hose can not enter the motor windings.Such protection is provided for outdoor motors. This also is applicable for terminal covers. Motor covers are sealed with rubber or other gaskets so as to avoid any liquids to enter the windings.For gaseous atmosphere such protection will not work. Normally motors are provided with IP44 protection for indoor applications.

A terminal box is very much part of the motor enclosure. As such when somebody claims IP 55 for his motor, it MUST include IP 55 for the terminal box too. This is achieved by suitbale gesketing of the terminal box covers and by suitable blanking plates for the gland holes.

But, I remember what I read in a Motor Installation Manual (way back in 1983). The motor was IP 55. The manufacturer had very beutifully put that "IP 55 is like virginity; Guaranteed only until first opening". When I contacted the motir manufcaturer for explanation, he explained that while the motor is despatched from his works he ensures that it is IP 55; but, what is the guarantee that the installation electrician would not loose or damage the terminal box cover gasket? If it so happens, (i.e.) lost or cracked gasket, the IP 55 for the terminal box is lost. I had to agree with him.