Dielectric boots are electrically insulating safety boots that are used where there is a risk of electric shock from high voltages. They provide protection because their insulating properties stop electric current from being grounded. High voltage electric current can stop the heart or produce fatal burns.
Dielectric boots are used for working on live power or in the area of live power as current can jump large distances, especially in wet or damp conditions. There have also been fatalities caused by digging in locations where power cables are buried underground and the cable has been inadvertently cut by a drill, shovel, or with a mole.
Dielectric boots are covered under the ASTM F2413-05 standard and covers minimum requirements for the design, performance, testing and classification of protective footwear. Footwear certified as meeting ASTM F2413-05 must meet the minimum requirements of Section 5.1 “Impact Resistant Footwear” and Section 5.2“Compression Resistant Footwear.” Additional sections have requirements of specialty shoes such as metatarsal protection, conductive protection, electric shock protection, static dissipative protection and protection against punctures.
ASTM specification must be marked with the specific portion of the standard with which it complies. One shoe of each pair must be clearly and legibly marked (stitched in, stamped on, pressure sensitive label, etc.) on either the surface of the tongue, gusset, shaft or quarter lining. An example of ASTM style markings for protective footwear is: ASTM F2413-05 M I/75/C/75/Mt75PREH
First Line: ASTM F2413-05:
This means the protective footwear meets the performance requirements of ASTM F2413 issued in 2005.
Second Line : M I/75 C/75 Mt75:
M in this case means the footwear is designed for a Male (F would be Female).
(I) denotes impact resistance followed by the impact resistance rating (75 or 50 in foot-pounds), (C) denotes compression resistance and the compression resistance rating (75 or 50 which correlates to 2500 pounds and 1750 pounds of compression
respectively). (Mt) designates that this shoe has metatarsal protection and rating (75 or 50 foot-pounds).
Third and Optional Fourth Line: PR EH.
The last two lines are used to identify footwear made to offer protection from other specific types of hazards referenced in the standard. They designate conductive(Cd) properties, electrical insulation properties (EH), static electricity
dissipative (SD), puncture resistance (PR), chainsaw cut resistance (CS) and dielectric insulation (DI), if applicable. The last line is only used when more than three sections apply. Electrical Hazard (EH) footwear is manufactured with non-conductive electrical shock resistant soles and heels.
The outsole can provide a secondary electrical shock resistance protection to the wearer against the hazards from an incidental contact with energized electrical circuits or parts. Testing ensures the materials are capable of withstanding 14,000 v at 60 Hz for one minute with no current flow or leakage current in excess of 3.0 mA, under dry conditions. (This is NOT usually acceptable for wet service or higher voltages.). ASTM 2413 cites ASTM F1117 for dielectric shoes.
Not many people are aware that Annex B2 of the standard for dielectric footwear - EN 50321-1:2018 (Electrically insulating footwear for working on low voltage installations), requires that all approved dielectric footwear is retested every year.