Electrical equipment should be kept clean for maximum efficiency and service longevity. Photo Credit: Andrew Barna, flickr (CC).
Keeping electrical equipment clean is an important part of any electrical preventive maintenance program, but using the wrong cleaning methods could be costly.
Determine the cleaning method by observing the type of contamination to be removed and the time allowed until the equipment needs to be returned to service.
Sufficient dry time is required when using liquid solvents or water to clean electrical equipment. Insulation should be tested to determine whether it has been properly reconditioned before re-energizing equipment.
Methods of Cleaning Electrical Apparatus
Never attempt to clean electrical power equipment while its energized. Remember to observe all safe work practices and lockout/tag out procedures prior to cleaning. Personnel should be properly qualified before cleaning electrical equipment.
1. Rags and Brushes
Wiping off dirt with a clean, dry, lint-free cloth or soft brush is usually satisfactory if the apparatus is small, the surfaces to be cleaned are accessible, and only dry dirt is to be removed.
Don't use waste rags when cleaning electrical equipment because lint will adhere to the insulation, acting as a further dirt-collecting agent, which can cause tracking. Cloth rags should be clean and free of oil, grease, and metallic deposits.
Use care to avoid damage to delicate parts. Rags can easily catch on edges other and sharp objects, which could damage small plastic or moving parts.
2. Liquid Solvents and Water
Accumulated dirt, oil, or grease might require a solvent to be removed. A rag barely moistened (not wet) with a nonflammable solvent can be used for wiping. Solvents used for cleaning of electrical equipment should be selected carefully to ensure compatibility with materials being cleaned.
Do not use any liquid cleaners, including spray cleaners, unless specified by the equipment manufacturer, because of the risk of residues causing damage, interfering with electrical or mechanical functions, or compromising the integrity of insulation surfaces.
Allow sufficient time for drying after cleaning equipment with a liquid solvent or water!
Observe all material data sheets prior to using chemical cleaners. Wear the required personal protective equipment (PPE) such as goggles, gloves, aprons, and respirators when working with potentially hazardous solvents.
3. Vacuum Cleaning
Loose dust, dirt, and particles can be removed using a vacuum-type cleaner with non-metallic attachments and hoses. Blowing equipment out with compressed air is likely to spread contamination and damage insulation.
Equipment enclosures and substation room filters should be cleaned at regular intervals and replaced if they are damaged or clogged. Loose hardware and debris should be removed from the enclosures. New or unusual wear or loss of parts occurring after the cleaning can be detected during subsequent maintenance.
4. Sweeping and Moping
If the sweeping of a substation room is required, use a sweeping compound to limit the amount of dirt and dust becoming airborne. When mopping, keep the mop bucket as far as practical from the switchgear to prevent damage from spillage.
Compressed Air Methods for Cleaning Electrical Equipment
Where dirt cannot be removed by wiping or vacuuming, compressed air blowing might be necessary.
CAUTION: Cleaning with compressed air can create a hazard to personnel and cause equipment to fail or malfunction. If compressed air is used, protection should be provided against injury to workers' faces and eyes from flying debris and to their lungs from dust inhalation.
The use of compressed air should comply with OSHA regulations in 29 CFR 1910.242(b), "Hand and Portable Powered Tools and Other Hand Held Equipment," including limiting air pressure for such cleaning to less than a gauge pressure of 208.85 kPa (30 psi) and the provision of effective chip guarding and appropriate personal protective equipment.
Use care when working with compressed air to avoid contaminants from become airborne, which can contaminate insulation surfaces, cause injury to personnel, or affect the mechanical operation of nearby equipment. Compressed air should be dry and directed in a manner to avoid further blockage of ventilation ducts and recesses in insulations.
Protection might also be needed against contamination of other nearby equipment if the insulation is cleaned in place with compressed air. Removed the apparatus to a suitable location for cleaning, or other exposed equipment should be covered before cleaning starts to keep the debris out.
Sandblasting and Shot Blasting
Electrical equipment might require cleaning by nonconductive sandblasting. Shot blasting should not be used.
Abrasive blasting operations should comply with OSHA regulations in 29 CFR 1910.94(a), "Occupational Health and Environmental Control — Ventilation." Use personal protective equipment to protect the face and eyes from abrasives and flying debris, and the lungs from dust inhalation.
Asbestos is a toxic substance subject to government regulations. Special considerations should be taken when cleaning aged equipment that may contain asbestos, especially when using compressed air methods. Knowledge of government regulations is required in handling asbestos and other such materials.