FAQ: Evolving Intrinsic Safety Standards

What does ‘Intrinsically Safe’ actually mean?


Electronics sometimes create tiny arcs or produce heat during normal operation; both of which could become an ignition source under the right circumstances. This likely doesn’t concern you unless, of course, you work in an area where tiny sparks can cause big explosions. In such a case, you have to use intrinsically safe radios… but what does that mean? Intrinsic Safety (IS) is an approved protection level for the safe operation of electronic equipment in explosive/hazardous locations by limiting the energy available for ignition. Basically, that means a device labeled ‘Intrinsically Safe’ must be incapable of producing heat or a spark sufficient to ignite an explosive atmosphere. Manufacturers accomplish this by incorporating several considerations into the design process including the reduction or elimination of internal sparking, control of component temperatures and the elimination of component spacing that could allow dust to short a circuit. The device is then subjected to testing in which combinations of internal failures are inflicted. Only after it passes the ignition test with these imposed failures present can it be certified IS.


Why are the regulations changing?


As IS standards evolved, they did so geographically. The result? Eleven different standards for the same technology from eleven different agencies dependent entirely upon the part of the world you’re doing work in (see Figure 1).


Eleven standards from eleven agencies.


As you might guess, this is not an ideal scenario for IS equipment manufacturers, end users, or the mutual advancement of technology. In an effort to make it easier to achieve global IS standards, the U.S. and Canada are adopting more stringent standards that are harmonious with international standards (IECEx/ATEX). It is important to note that there have been no safety issues found with the current standards; it was simply changed to help facilitate world trade without redundant testing and certification.


What changes are happening?


Factory Mutual (FM) released a more stringent standard (FM 3610_10) to harmonize with international standards. These new requirements impose a lower transmit power level and other restrictions that would mandate a costly redesign of all IS radios. Fortunately, ANSI/TIA-4950 was developed to provide a standalone set of IS standards specific to two-way radios. ANSI/TIA-4950 is similar to the current standard (FM 361-1988) and radio manufacturers are now given the choice to design products to international standards or domestic standards. Motorola Solutions (among other manufacturers) is already transitioning to the new TIA standard with UL administering the compliance testing.


Who makes the regulations and who certifies them?


The Telecommunications Industry Association (TIA) is accredited by the American National Standards Institute (ANSI) to develop industry standards for communication technologies products. FM Approvals (FM) and Underwriters Laboratories (UL) are both private companies that certify and test products as well as write standards. FM certifies equipment to FM standards while UL certifies to the new ANSI/TIA standards.


What does that mean for you?


Radio manufacturers can no longer manufacture devices to FM 361-1988 standards after December 31, 2015. FM approval label will change to a UL approval label on IS devices/batteries. FM approved radios in the field will maintain approval status (provided any repairs are done at an FM audited site). Motorola will also continue to sell FM replacement batteries and accessories. All new UL-certified devices are approved for operation in the same areas as the previous FM certification allowed.


IMPORTANT: Your current inventory of FM radios, batteries and accessories will not be interchangeable with their new UL counterparts. This will create confusion when swapping batteries or accessories in the field; equipment should be clearly labeled/distinguished or kept separate. Many companies are stocking up on FM equipment to prevent this potential mismatching. 


Summary/next steps?


Safety certification standards in North American Class I/Div I areas are gradually moving to harmonize with more stringent international standards. This is to simplify global trading, NOT because there were any safety issues with the previous standards. Many LMR manufacturers will be adopting the new ANSI/TIA-4950 standards, which are similar to the previous FM standards, and will be utilizing UL for testing and certification. Keep this in mind when ordering and receiving radio equipment. Many customers have been specifying ‘FM Approved’ radios on their POs; instead, you should begin specifying ‘Intrinsically Safe’ radios to avoid confusion. FM batteries/accessories are NOT interchangeable with new UL radios. If you need more FM radios to utilize your inventory of FM batteries & accessories, they will need to be ordered (and shipped by the manufacturer) prior to the discontinuation date of December 31, 2015. If you have any questions or would like additional information; please don’t hesitate to contact us. 


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