Is it permitted (not necessarily good practice) to troubleshoot or repair an intrinsically safe circuit located in a DIV 1 location? Some manufacturers of IS equipment advertise that one of the advantages of IS equipment is that you can troubleshoot the equipment in the hazardous (classified) atmosphere without a "hot work" permit. Does this conflict with OSHA "Log out, tag out" requirements?
Thank you

 

You can safely (whether it is "permitted" or not is another issue) troubleshoot faults in an IS circuit without isolating the circuit - PROVIDED you do not do anything that could inject energy downstream of the barriers. In particular, if you are using eg a multimeter to check continuity or circuit voltage in the protected part of the circuit, it must be a meter certified as IS for the particular atmosphere you are working in. You must also consider the possibility of adding capacitance or inductance to the loop. Note that this applies to any measurements made on the field side of the barriers, even in the marshalling cubicle or junction box in a safe area. It is not a good idea to try to repair IS certified components. Because IS circuits usually work at less than 30 V, electrical safety rules may not apply - but think about what your tests could do to the
process or plant you are trying to protect.

Bruce

 

Two issues are covered here: work permit and spark/explosion concern. It may not be required to obtain a hot work permit, as most instrument maintenance work don't include "hot" works like welding, but you would still require a "cold" work permit, and you may have to tag out affected equipment as well. Operations people would have your neck if they see you working without any permit in hazardous areas. Regarding spark potential of the work, IS circuits by themselves are safe. However, the right type of testing equipment for IS circuits must be used.

 

I've not familiar with a "cold work" permit. Could you give me some information or explanation? Thank you.

 

Usually that's just a permit to enter a hazardous area. It may have requirements that vary with the environment.. Hot work requires more precautions like fire spotters and attendants, oxygen monitors, etc. Confined spaces almost always require a permit and oxygen monitoring.

Regards
cww