On The Audit Trail:
Electrical Safety Considerations for Paint Booths
Curt Johnson, CPEA, STC Senior Program Director, Richmond, TX
When conducting spray finishing using flammable and/or combustible materials, many facilities use a paint booth or a ventilated spray area to limit employee exposure and prevent accumulation of explosive atmospheres. At the same time, most equipment used in and around such booths requires electricity. Because the vapors from flammable and combustible liquids don't play well with electricity (think fires and explosions), OSHA has established electrical requirements in and around paint booths and spraying areas. Although auditors should have a thorough understanding of these electrical requirements, OSHA's requirements for electrical components leave many auditors and facility safety managers scratching their heads. In my opinion, some of this confusion arises from the disorganization of OSHA's requirements. This article attempts to organize the information about electrical requirements in a more user friendly manner.
OSHA's General Industry standards (29 CFR 1910) regulate paint booths1 and spray areas under both the Ventilation requirements in Subpart G (29 CFR 1910.94) and the Spray Finishing Using Flammable and Combustible Liquids requirements in Subpart H ((29 CFR 1910.107). This article focuses on the design and operating requirements for electrical components in the Subpart H regulations and how they cross-reference with OSHA's Subpart S (Electrical)requirements.
Summary of Applicable OSHA Requirements
OSHA defines the spraying area as any area where dangerous quantities of flammable vapors, mists, and the like result from spraying processes. A spray booth is a power-ventilated structure that completely or partially encloses a spraying operation to control the flammable vapors and other materials. The inside of a spray booth can be considered a spraying area if the ventilation fails or its efficiency has been limited, such as from paint build-up on filters. Open-faced spray booths need to be thought of as spraying areas as well, since they have no doors to serve as a partition from other activities.
29 CFR 1910.107(c) contains the general requirements for spray finishing operations with regard to electrical issues and other sources of ignition. This section also identifies alternative or more specific requirements. For example, automobile undercoating spray operations in garages are exempted from many of the requirements when using certain materials that are less hazardous or solvents with a flash point exceeding 100°F (thus 29 CFR 1910.107(c)(1) refers automobile undercoaters to 1910.107(k)).
OSHA requirements, fire codes, and electrical/building codes are quite specific about electrical wiring and equipment located inside a paint booth or spraying area and in the downstream exhaust path. Paint booths are generally installed with great care to reduce the potential for explosive vapors and combustible residues-no one would want to invest in a paint booth and then watch it burn down or hurt someone. According to 29 CFR 1910.107(c)(5), no electrical equipment can be placed in a spray area where combustible deposits may accumulate except the following:
- Wiring in rigid conduit or boxes or fittings containing no taps, splices, or terminal connections, or
- Equipment that is specifically approved for locations containing both deposits of readily ignitable residue and explosive vapors.
Furthermore, OSHA prohibits space-heating appliances, steampipes, and other hot surfaces from being located in a spraying area (29 CFR 1910.107(c)(3)).Finally,portable electric lamps cannot be used inside a spraying area during spraying activities (29 CFR 1910.107(c)(8)). That's why you often see skylights and clear panels lighted from outside the booth. Paint booths might be heated, but the heating elements must be located outside of the painting areas and upstream of the spraying activity.
OSHA also regulates activity and equipment near a spray area. The following items are prohibited within 20 feet of a spray area unless separated by a partition:
- Any open flames and equipment that can produce sparks (29 CFR 1910.107(c)(2)), and
- Electric lighting, unless it is totally enclosed to prevent paint deposits on the lamp itself and protected from mechanical injury by suitable guards or by location (29 CFR 1910.107(c)(7)).
In its spray finishing rules (29 CFR 1910.107), OSHA states that wiring and electrical equipment must conform to the requirements in 29 CFR 1910.107(c) as well as the electrical requirements under Subpart S (29 CFR 1910.301 - 1910.399). In particular, 29 CFR 1910.107(c)(6) and (c)(8) state that certain items in and around spraying areas must meet the requirements forhazardous locations under Subpart S, as follows:
- Wiring and equipment that is inside a spraying area but not subject to combustible deposits must
- be explosion-proof type approved for Class I, Group D locations, and
- conform to the electrical requirements for Class I, Division 1 hazardous locations.
- Wiring and equipment that is outside a spraying area but within 20 feet and not separated by a partition must
- not produce sparks under normal operating conditions, and
- conform to the electrical requirements for Class I, Division 2 hazardous locations.
- Portable electric lamps may be used inside of a spraying area during cleaning or repairs, but only if approved for Hazardous Class I locations.
The requirements for electrical items in hazardous locations (of all classes) are found in 29 CFR 1910.307. With respect to the electrical requirements for paint booths and spraying areas, auditors can normally focus on the following criteria from 29 CFR 1910.307(c):
Equipment, wiring methods, and installations of equipment in hazardous (classified) locations shall be
- intrinsically safe,
- approved for the hazardous (classified) location, or
- safe for the hazardous (classified) location.
The section goes on to explain what is required to satisfy each of these three options. While not defined within the electrical sections of OSHA, intrinsically safe means that the available electrical energy is limited such that even if the electrical components spark under normal operating conditions, they do not release enough energy to cause ignition.2 That is, the wiring does not possess enough electrical energy for a spark to ignite flammable gas. If wiring and equipment is intrinsically safe, it can be used in any of OSHA's hazardous locations. Equipment that is intrinsically safe was designed and constructed this way, and there will be documentation to support this. But intrinsically safe equipment is normally limited to signal and control circuits that can operate with low currents and voltages.
If appropriately designed, higher current and voltage equipment can be approved for use in hazardous (classified) locations by a nationally recognized testing laboratory (e.g., Underwriters Laboratories). Other parts of 29 CFR 1910.307 define specific requirements for particular location classes and divisions (e.g., being explosion-proof, dust-tight, hermetically sealed, etc.) and refer to NFPA 70, the National Electrical Code, for the meaning of these requirements. Fortunately for auditors, this equipment must bear a label identifying it as suitable for the particular hazardous location. Figure 1 shows an example of such a label for a piece of equipment that is suitable for a Class I, Division 2 location.
Figure 1 - Example of a label for a piece of electrical equipment suitable for use in a Class I, Division 2 hazardous location. (Source: www.cisco.com/en/US/docs/wireless/access_point/1552hz/installation/guide/1552hz_ch2.html)
Safe for the hazardous (classified) location is the last option allowed for electrical equipment and wiring. This provision (in 29 CFR 1910.307(c)(3)) allows the employer to demonstrate that the system as designed meets the needs and requirements for the location:
Equipment that is safe for the location shall be of a type and design that the employer demonstrates will provide protection from the hazards arising from the combustibility and flammability of vapors, liquids, gases, dusts, or fibers involved.
OSHA notes that the National Electrical Code, NFPA 70, contains guidelines for determining the type and design of equipment and installations that an employer can use to demonstrate this requirement. Therefore a qualified employee (or a qualified person acting on behalf of the employer)may produce a description defining how the design meets the requirements of NFPA 70 and thusdemonstrate that the installation issafefor the hazardous location. As examples, NFPA contains diagrams of protection and separation distances for paint booths and associated electrical equipment and allows exceptions to OSHA's absolute exclusion distances.
OSHA has one additional electrical requirement for hazardous locations, including paint booths or spraying areas,built after August 13, 2007. Such installationsmust be documented, and the documentation must be available to those who are authorized to design, install, inspect, maintain, or operate electric equipment at the location (29 CFR 1910.307(b)).
As is always the case when identifying nonconformities and potential risks to an operation, it is incumbent upon auditors to accurately present their findings so the facility can responsibly design and implement an action plan. The balance of this article discusses audit findings and, in some cases, what one would expect in the related action item.
In my experience, wiring located inside of paint booths and spray areas is normally installed to be intrinsically safe. Audit findings, therefore, rarely involve wiring or lighting inside of a paint booth or spray area that was installed when the booth or area was built. It is not unusual, however, to observe portable electrical equipment brought into a spray area that is not intrinsically safe (e.g., cellular phones, portable stereos, extra lighting, and portable heaters).
Another finding I've frequently observed is an insufficient separation from the spraying area. In most cases facilities were originally designed properly and paint booths and spray areas were installed carefully, but activities may have been moved and other equipment may have been brought into the facility over time, causing problems. I have seen uncovered lamps, spark-producing grinders, and even welding units that had been moved into the 20-foot exclusion zone without being separated by a partition. When considering partitions, by the way, OSHA provided the following guidance in 1976:
An adequate partition is one that would be vapor proof, and of such a height that the vapors and/or spray material could not go over the top. For most operations, eight feet should be sufficient.
To successfully audit electrical requirements for paint booths and spraying areas, I use a combination of common sense and diligence. While I readily admit to not being trained as an electrician and only have a passing understanding of the National Electric Code, I can tell when lighting or wiring is not enclosed, and I know that power strips and most plug-in tools and equipment are not approved for use in hazardous locations. Beyond those basics, however, I would need to check to ensure that all equipment in an exclusion area bears a label showing it is approved for use in a hazardous location. Finally, if something is still in question, rather than assuming that I know better, I check with facility personnel. The maintenance manager or an electrician may have helped install the paint booth or spraying area. They might even have a copy of a demonstration showing how their operation meets the requirements. With access to the employer's demonstration, it is a relatively simple task to verify that conditions havenot changed. If the employer has substituted a different piece of equipment or an item is not contained in the demonstration (probably because it was moved into the area later), there's a problem.
The findings I've discussed above are relatively clear cut, and the actions required to correct the problem and prevent its recurrence are also relatively straightforward. First, offending item(s) must be moved outside of the work area and zone of separation. To prevent future problems, the employer must instill an understanding of requirements, using training and/or signs, and then verify compliance through regular inspection.
Findings concerning unacceptable electrical equipment in a hazardous location (e.g., inside a paint booth or within 20 feet of a spray area) should fully explain the requirement and describe the finding so that the facility can choose the best option for action. The following example describes a finding pursuant to 29 CFR 1910.107(c)(8) and provides the three possible options for action under 29 CFR 1910.307(c):
Wiring and equipment (e.g., metal lathe, radio, computer terminal, power strip) was observed within 20 feet of the spraying area,was not separated by a partition, and did not conform to the electrical requirements for Class I, Division 2 hazardous locations by being either:
- intrinsically safe,
- approved for the hazardous (classified) location, or
- demonstrated as safe for the hazardous (classified) location.
When facility personnel meet to develop their action plan, their approach could be to install a partition, move the equipment, upgrade to equipment that is approved for the hazardous location, or develop a demonstration that whatever they plan to keep within 20 feet of the spray area is safe considering their operating conditions.
Although OSHA's electrical requirements within paint booths and spray areas can seem overwhelming, the following tips can help you successfully navigate the requirements:
- Break down and evaluate the area based on whether the wiring and equipment is actually inside the booth or outside but within the 20-foot separation distance;
- For electrical equipment that is located inside a hazardous location, look for labels that identify whether it is properly rated for the class and division; and
- If it is still unclear, ask to review the employer's demonstration to determine which equipment is allowed in that space.
Curt Johnson, CPEA, is an STC Senior Program Director in Richmond, TX. He has more than 30 years experience in the development and implementation of environmental, health and safety management systems. Recent projects include developing the management system and its documentation for a major food producer; analyzing regulatory requirements for a large U.S. oil refiner and distributor; and assessing management systems conformance for an offshore fleet operation.
To discuss this article or for more information about STC's audit services, contact Curt at (281) 341-8289 or email@example.com.
1 OSHA uses the terms "spray booth" and "spray area" to encompass spray application of any flammable or combustible material. Because the majority of persons are familiar with painting activities, I refer to "paint booths" in this article.