InfraMation 2018 Application Paper Submission
Vice President US Infrared Inspections
The marijuana grow industry in the United States is undergoing rapid expansion. The discovery of the medical benefits of the drug is gaining traction in wide areas. Electrical power consumption is very heavy due to the type of equipment used to grow the product. Along with this expansion comes the possibility of life and property damage due to unforeseen causes of electrical fires. Many of the fires can be directly attributed to poor power quality, excessive power usage and electrical harmonic distortion.
This discussion will focus on harmonics in electrical power systems and how that both impacts and leads to excessive power grid imbalances in commercial and residential grow operations. Infrared Thermography can be used to forecast and possibly prevent electrical fires, by establishing levels of criticality, methods and corrective procedures. The equipment used in the operation includes Air Conditioners, Fans, Air Scrubbers, Humidifiers, De-Humidifiers, Metal Halide Luminaires (conventional or electronic ballasts) and Carbon Dioxide Injection systems. The Marijuana Grow industry consumes 1% of total U.S. electrical output.
Harmonics are sinusoidal wave forms at frequencies that are multiples of the power system frequency, typically 60Hz, in the U.S. Harmonics can be deconstructed into discrete sinusoids of 2nd and 3rd harmonics. Harmonics are caused by saturated undersized transformers, personal computers, adjustable speed drives, photocopiers, electronic ballasts, etc. These electronic loads demand current only at peaks of voltage waveforms
These harmonic distortions are caused by unbalanced/overloaded energized equipment; extended power consumption or excessive power consumption. The Neutral conductor, in an electrical system, is the “master” conductor, most responsible for sensing and opening protective devices under overloaded or short-circuited conditions. It will perform this function within 5-25 cycles. (Alternating Current is generated at 60 cycles per second.) When this conductor is compromised and doesn’t perform well, it builds up heat. If the system loses the Neutral completely, the energized conductors will lose their reference, and the system will be unstable and out of balance. The system approaches catastrophic conditions.
The excessive heat saturates the mechanical connections, and they become loosened. The cycle oscillates and continues to build until there is failure of the mechanical connections and lugs, and often a fire results. Many of the single phase electrical services present thru the meter and meter base, which is in series with the main service. When the Neutral lugs default from excessive power consumption, extended power consumption, unbalanced or overloaded conditions, the meter will see more than 12KW, and will breakdown.
Three phase systems are designed so that the meter is not in series with the service meter but gets its information from a set of CT’s (current transformers, and ratios). If all the conditions exist, especially with the service neutral connections, the prospect of losing the transformer bank becomes the reality.
This discussion gives insight to the effects of harmonic distortion; to understand how harmonics can play a role that may lead to electrical fires, in the marijuana grow industry. While harmonics aren’t the primary cause of these fires, there are indicators that the electrical system is experiencing harmonic issues. One of the indicators is the lighting, in the building, suddenly blinks off and on, seemingly spontaneously, for no apparent reason. Extreme care must be exercised by wearing the proper PPE equipment when exposed to electrical equipment, operating under full load. The recommendation is to be familiar with NFPA 70E, Arc Flash information and OSHA standards. Every electrical service demonstrating harmonic imbalances or distortion, affects the entire electrical grid. The Utility Industry and the NFPA are establishing best practices and examples of a well- balanced power grid The NFPA is bringing forth a new Fire Code chapter(38): “Marijuana Growing, Processing or Extraction Facilities”, in the latter part of 2018. Furthermore, utilities are searching for information, in order to forecast the future demand on the electrical infrastructure, associated with the speed of the growth of this growing industry.
Marijuana Grow & Extraction Facilities
Marijuana Facility Guidance PDF March 11, 2016
Proposed National Fire Codes in works for Cannabis Business
Mike Holt’s Power Quality Book
How To Check For Harmonics in an Electrical Power System
Marijuana Facilities: Codes, Standards, and Managing the Hazards
ABOUT THE AUTHOR
Gregory Black is a Level III thermographer; a Master Electrician, including Radio Broadcast Electronics. Mr. Black has residential, commercial, industrial, Smelter/Alloy and Utility electrical experience. A current member of the IEAI, IBEW and an instructor for JATC electrical apprenticeship programs, Mr. Black is Vice President of U.S Infrared Inspections’ Western Division