chazb
Member
- Location
- Colorado Springs, Colorado. USA
I have a question regarding a structure/space not being considered a hazardous location. The facility I work at is preparing to bring two large industrial boilers on line. Other electrical technicians have questioned why the structures these units are in would not be classified as a "hazardous location"? I recently was asked to review a work order for the installation of an EPO station on the exterior of the "houses" the boilers are in and after performing a walk-down of the units, I myself questioned why the structures they are in, is not considered at a minimum a Class 1, Div. 2 location. Here is some info on the spaces: The boilers are dual fuel and supplied with both natural gas and #2 fuel oil. The natural gas line is 2-1/2" and operates at 5lbs of pressure. The fuel oil feed line is 3/4" and has a small assist pump located inside the space. Numerous valves, regulators and other instruments control/monitor flow, pressure, etc. and are co-located inside the space occupied by the boilers. As well, all of the electrical power, control cabinets and disconnects are installed inside the houses. At present, an operator or maintenance technician would have to enter the structure to engage the EPO switch in the event of an "abnormal operating condition" or an actual emergency. There are not any gas detection devices inside the houses nor are there any exterior mounted signaling or alarm devices to alert an operator/technician of a hazardous condition inside. Both fuel types have control interlocks to shut down fuel delivery into the boiler combustion chamber in the event of a malfunction. However, the fuel shut- offs do not restrict entry into the boiler "houses" themselves. Another consideration is that there isn't any provision for ventilation of the space other than an exhaust fan controlled by a wall thermostat. This fan of course is not designed to vent any type of vapors or gases but simply hot air. Finally, the large boiler exhaust fan(s) only vent combustion air and will no doubt cause considerable vibration inside the boiler houses so the probability of valve, instrument, seal and gasket failure or leakage of either or both of the fuel delivery lines due to excessive vibration seems likely under normal operating conditions. That being said, the potential for the accumulation of explosive gases, liquids or vapors does exist.
After reviewing 500.5(B)(2) paragraph (1), it would appear clear to me that these spaces would meet the conditions outlined in the article and should therefore, be considered a hazardous location? As well, I think the EPO switch should be remoted away from the houses by a considerable distance rather than mounted on them and that some type of leak detection device and an externally mounted alarm/signaling device(s) should be installed. Among the other electricians familiar with the boiler units/houses, there is a consensus in agreement with these evaluations. Is it possible that since these units are manufactured as "package units", they have been UL approved for this configuration and do not meet the conditions described in 500.5(B)(2)? Thanks.
After reviewing 500.5(B)(2) paragraph (1), it would appear clear to me that these spaces would meet the conditions outlined in the article and should therefore, be considered a hazardous location? As well, I think the EPO switch should be remoted away from the houses by a considerable distance rather than mounted on them and that some type of leak detection device and an externally mounted alarm/signaling device(s) should be installed. Among the other electricians familiar with the boiler units/houses, there is a consensus in agreement with these evaluations. Is it possible that since these units are manufactured as "package units", they have been UL approved for this configuration and do not meet the conditions described in 500.5(B)(2)? Thanks.
