IS Barriers and EEXe JB


Thread Starter


If you are limiting the energy into a haz area using a barrier or isolator for, say, a EEx ia/ib or EEx [ia/ib] loop powered/simple device, which is terminated in a junction box in the haz area, does the junction box need to be EEx e rated or can a normal enclosure with a IP rating above IP55 be used?
My caveat is that you really need to read and understand your local legal and company requirements to determine what the exact requirements are.

That said my understanding of current practice in my area (Europe) is that the I.S. standards do not require explicitly the use of Exe JBs. However both the standards for devices and installations do place construction constraints on the equipment used. The reason Exe boxes have been used in the past is that they have satisfied these constraints.

If applicable check out the relevant parts of IEC60079 for guidance.

Hope this helps.

The same age old question!!!! This subject keeps coming up every now and then with different opinions depending on where you are based.

The answer is really quite easy. If your Intrinsically Safe barriers or Galvanic Isolators are mounted in a SAFE area, then the external equipment need only be IP rated. If, however, your barriers, etc. are field mounted in a hazardous area then the JBs, etc. need to be certified EEx e.
Dear TXDMan,

It depends on the device, if it is a EEx ia/ib or EEx [ia/ib] loop powered/simple device, then it is not required to be kept in ex-proof JB. However if it is a un-certified device, not a simple device, then it is required to be kept in ex-proof JB.

C Potdar
C Potdar-

If the device connected to the barrier is not considered as a simple apparatus or is not certified Ex i, then it should not be connected to the barrier regardless of whether it is in an Ex d enclosure or not. This is because any energy stored within the device could be released into the cable thus causing a potential hazard.

Depending on how the barrier/interface is certified, you may not need an Ex e enclosure. I have checked the ATEX certificate for the MTL5500 series and this only requires an IP54 enclosure when the isolators are mounted in zone2, there will be a similar requirement for the FM Div 2 approval.