NFPA 70E
NFPA 70E
National Fire Protection Association
Five to ten arc flash explosions occur in electric equipment every day in the United States, according to statistics compiled by CapSchell, Inc. This number does not include cases in which the victim is sent to an ordinary hospital or clinic for medical treatment. Unreported cases and "near misses" are estimated to be many times this number. Instead these injuries are so severe the victims require treatment from a special burn centre.
What is an Arc Flash?
Think of an arc flash as a short circuit through the air. In an arc flash incident, an enormous amount of concentrated radiant energy explodes out wards from the electrical equipment (see video), creating pressure waves that can damage a persons hearing, a high-intensity flash that can damage their eyesight and a superheated ball of gas that can severely burn a workers body and melt metal. The pressure waves can also send loose material like pieces of damaged equipment, tools and other objects flying through the air.
The NFPA 70E regulations define a series of boundaries related to electrical safety when working on energised equipment.
Prohibited Approach Boundary
Restricted Approach Boundary
Limited Approach Boundary
Flash Protection Boundary
The flash protection boundaries define the safe working distances in which any tradesman can operate in from a energised component. Thermographers must be fully conversant with these regulations, as occasionally we need covers to be removed to allow access for an inspection to be completed.
Remember ignorance is no excuse!
Note:
The NFPA 70E regulations also stipulate that unless the thermographer is a certified electrician they will need to be accompanied by qualified personnel.
NFPA 70E 2004 Equipment Requirements
Once a thermographer has identified the need to complete a live inspection within a flash protection boundary, they must then identify the level of Personal Protection Equipment PPE that is required.
Below is the proposed equipment requirement based on the expected Arc Flash energy level of the equipment being inspected.
Arc flash is a serious hazard that can be devastating to those exposed to it. It can also cause lengthy downtime to repair or replace severely damaged equipment. The requirements of NFPA 70E help plant and facility managers to reduce the probability of an arc flash event and its effects. This is where the use of thermography in conjunction with infrared windows can assist
The vast majority of arc flash incidents occur when there is a change of state within the panel (opening the panel doors, removing covers, etc) or through operator error (dropping tools, touching live components, etc). Using infrared windows means that there is no need to remove covers in order to allow a full thermographic inspection of an electrical panel to be completed, thus negating exposing an operator to energised electrical components, therefore removing the major causes of arc flash incidents.
Inspecting electrical systems during peak loading with no interruption to process has always been the preferred time to test an electrical system, however, due to the perceived risks and downtime associated with traditional inspection methods is normally the most difficult time to gain access, thermographic inspections in conjunction with infrared windows allow you to inspect any system at any time with no interruption to process, thus allowing a more accurate assessment of the electrical systems condition to be completed.
REMEMBER infrared windows are not designed to protect you from an arc flash incident (see video) they are designed to allow a thermographer safe access to inspect the condition of electrical switchgear, transformers, etc., and thus REDUCE the RISK of failure through regular, safe, live inspections.
"PREVENTION IS BETTER THAN CURE"
Global Maintenance Technologies Ltd
+44 (0) 1245 500 460
g-m-tech.com