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  • Writer's pictureJames Cade

Recommended Work and Safety Practices for Shops Maintaining Electric Vehicles

Updated: Jun 27, 2023

Prepared by: James Cade

PH- 515-528-5497


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Recommended Work and Safety Practices for Shops Maintaining Electric Vehicles

Table of Contents

I. Purpose of This Document………..……………….…..........................………. Page 3

II. Responsibilities…….…………......................…………………..……………… Page 4

a. Management

b. Technicians

III. Definition of High Voltage and Potential Human Impacts…..........................Page 4

IV. Importance of Orange Cables…………...........................……………..….…. Page 7

V. Personal Protection Equipment (PPE)…........................................................ Page 8

a. Clothing and Personal Items

b. Safety Shoe Requirements

c. Insulated Rubber and Leather Safety Gloves

d. ARC Flash Faceguard, Safety Glasses, and Ear Plugs

e. Fluke 1577 Insulation and Multimeter (2-in-1), Or Equivalent

VI. Tooling Requirements……….....…………….......................…………………. Page 13

a. Approach Boundary Barrier and Lockout-Tagout (LOTO) Procedures

b. Recue Stick

c. Insulated Tool Kit

VII. Lifts……………………….…..……….......................……………………………Page 17

VIII. Glossary of Terms…...........….…………………….......................……………Page 18

Work and Safety Practices for Shops Maintaining Electric Vehicles

I. Purpose of This Document

Interest in electric vehicles (EV) is growing at an extremely fast rate, both in the automotive and commercial truck segments. EVs use many of the same components as internal combustion engine (ICE) vehicles but use electric motors for propulsion instead of gasoline or diesel. The energy to drive the electric motors is stored in on-board battery packs. The electric motors and their controllers, the battery packs, and orange colored wiring all make up what is known as the high voltage (HV) system of an EV. The HV system of an EV contains enough electric force to severely injure or cause loss of life, for not only those performing repairs but also for those who may be in proximity to the work area. For this reason, it is imperative that proper EV safety and work practices are not followed.

The purpose of this document is to outline the responsibilities, the required safe work practices and procedures, and the tooling required for person’s performing repairs on EV HV systems. This document does not provide information on how to repair HV systems of EVs but defines the safety practices to be used during any HV system repairs. The appropriate vehicle manufacturer repair guidelines are to be consulted for specific HV repair procedures. Strict adherence to this document’s practices, along with the vehicle manufacturer’s work practices will mitigate the risk for the repairing technician and other shop personnel.

The procedures outlined in this document are only applicable to an EV when the HV system or its components are to be repaired or replaced. Repairs or replacement of components that are not part of the HV system of an EV are not subject to the EV Work Practices guidelines. These Work and Safety Practices only apply when HV systems are to be diagnosed, repaired or components replaced. Any questions as to when the HV system EV Work and Safety Practices guidelines are to be applied must be directed to your supervision and/or vehicle OEM.

If repairs are needed to an EV’s HV system, the HV system must be de-energized using the OEM’s procedures for isolating the EV’s battery packs from the rest of the vehicle. As per FMCSA guidelines for EV design, Master Service Disconnects (MSD) are required to isolate the battery pack from the rest of the vehicle. Refer to the appropriate OEM service manual to determine location, type and number of MSDs used.

Once MSDs are removed, they are to be secured as outlined in the organization’s lock-out-tag-out (LOTO) procedures to ensure HV system is not unintentionally re-energized.

All efforts are to be made to perform repairs to an EV’s HV system and its components after the HV system is de-energized. As per the National Fire Protection (NFPA) 70E Association’s “Standard for Electrical Safety in the Workplace” and applicable OSHA requirements, any repairs performed on an energized HV system must be approved by the appropriate level of supervision.

There is no way to turn off an EV’s battery pack. DO NOT OPEN BATTERY PACKS!

Information outlined in this document is a guideline and must not be used as the sole reference for repairs to a HV system of an EV. Specific OEM guidelines and procedures must be consulted and implemented before performing any HV repairs to an EV.

II. Responsibilities

To properly and safely maintain EVs, both the company and technician(s) have responsibilities.

a. Company Responsibilities

• Provide proper EV training and supervision to develop qualified repair personnel.

• Proper access to vehicles needing repairs.

• Providing adequate and complete documentation for repair processes

• Availability of the correct tools for the safe operation and maintenance of the vehicle(s)

• Ensuring proper illumination of the work area

• Providing a safe work environment

b. Technician Responsibilities

• Understand the hazards associated with HV work.

• Remain continuously alert and aware of the potential hazards.

• Use the proper tools and procedures for the work.

• Examine all documents provided relevant to the work.

• Maintain clean and safe work environment.

• Use and maintain the proper PPE and tools required to perform the work safely.

• Report any incident that resulted in, or could have resulted in, injury or damage to


III. Definition of High Voltage and Potential Human Impacts

The Occupational Safety and Health Administration (OSHA) defines HV in the automotive world as anything greater than 60 volts direct current (DC) or 30 volts alternating current (AC). Any components utilizing HV exceeding the previously mentioned thresholds are required to display at least one of the following labels. The purpose of this signage is to warn that HV safety protocols and proper personal protection equipment (PPE) are required when interacting with these systems.

HV safety training, vehicle specific training and PPE are required for a technician to touch, repair, or replace any of the components or systems displaying these symbols.

Always assume that a HV system is energized until it has been verified, with the appropriate test equipment, that it has been de-energized.

Be advised that instead of labels, some high voltage components may have the warning sign embossed onto their surface and may not be highlighted with the previously indicated colors.

Warning Label Embossed into Component

Once verified that the EV’s HV system is de- energized (batteries isolated from the HV system) the use of PPE is no longer required. In a de-energized state, all HV components, except for the battery packs, can be accessed and repaired without use of HV PPE.

The use of HV safety practices and PPE only apply to the repair of HV system of the EV. There are many components and systems on an EV that are like an ICE vehicle and can be adjusted or repaired without de-energizing the vehicle or required use of PPE as outlined in the HV safety protocols.

It is important to understand the relationship between HV and current (amps). The battery packs of automotive applications such as Tesla Model 3 vehicles are rated at 60 to 90 kWh, meaning they can produce 60,000 to 90,000 watts of power per hour. Using the following formula, this means that a 90kWh battery pack will deliver 187.5 amps of power.

The following is an overview of the effects of varying levels of electric current on the human body;

  • Below 1 mA (milli equals one thousandth, in this case on thousandths of 1 amp) current is not perceptible and there is no cause for concern

  • From 1 mA to 5 mA, a slight shock is felt, not painful but disturbing, and the average individual can let go of the component they have come in contact with

  • Coming in to contact with a circuit of 6 to 30 mA will result in a “freezing” of muscles and in the case of contractor muscles (hands, arms) the person may not be able to “let go” or disengage from the circuit or component. When extensor muscles (legs or hips) are excited by shock, the person may be thrown away from the power source, in some cases many feet away.

  • Contact with a circuit with 50 to 150 mA can cause extreme pain, respiratory arrest, and severe muscle reactions. The encounter leaves burned marks on the body where the power entered and exited the body. Death is possible.

  • 1 to 4.3 Amps will interrupt the rhythmic pumping of the heart and cease blood flow to the body. Muscular contraction occurs and severe nerve damage is possible; death is likely.

  • Contact with a circuit of 5 Amps and above, will cause serious burns that may require amputation of a limb or cause severe injury to internal organs if person survives; death is probable.

Commercial truck platforms contain battery packs of 450 to 800 kWh of power that will generate amps at power levels that can cause severe injury or loss of life if the proper safety procedures and equipment are not used.

Always follow the proper procedures and use the required PPE to avoid injury or loss of life when accessing HV systems on EVs.

IV. Importance of Orange Cables

HV wiring/cables on all automotive and commercial vehicles are colored orange to identify they are part of the HV system of the vehicle. Although HV wiring/cables are fully insulated, they should not be contacted or handled until it is verified that the HV system has been de-energized. Do not weld, cut, or drill near any orange HV lines or cables.

HV cables will have double or triple step connectors to make it more difficult to remove without the proper training or knowledge. For more information on how to disengage connectors, refer to the appropriate vehicle manufacturer service literature. If the HV system is energized, proper PPE must be used when disengaging or engaging HV cables or wiring. Once the HV system is de-energized connectors can be disconnected without the use of PPE.

HV safety training, vehicle specific training, and PPE are required to access HV connectors.

Examples of High Voltage Cables and Wiring

1. The conductor stranded bare copper.

2. Tape plastic

3. Insulation

4. Tin plated screen to reduce electro-magnetic noise.

5. Plastic or aluminum screen

6. Elastomer sheath, orange

V. Personal Protection Equipment (PPE)

Personal Protection Equipment (PPE) is designed to minimize the risks to technicians when working with HV systems on EVs. Due to the voltage levels of HV systems in commercial EVs, the following PPE is to be used whenever a technician is working on or near an energized HV system.

PPE must be worn when testing, energizing or deenergizing the HV system of an EV.

Disengaging the HV system on a vehicle involves isolating the batteries from the vehicle by removing or turning off the Manual Service Disconnects (MSD) for the vehicle. This deenergizing process is unique to each vehicle manufacturer and the proper training on the vehicle specific procedure is required before a technician is authorized to perform. The MSDs will be covered in more detail later in this document.

PPE for HV is a multi-layered system designed to minimize risk to the technician. The following equipment and their procedures are required to be used by technicians when working on HV systems of EVs.

a. Clothing and Personal Items

When dealing with an energized HV system, an arc flash (a sudden flashover of electric current due to it leaving its intended path and traveling through the air to a ground) is possible and utilizing the proper clothing is one way to minimize injuries to technicians. Due to the potential temperatures generated by an arc flash, polyester or synthetic clothing may melt and become embedded into a technician’s skin if an Arc Flash occurs.

The National Fire Protection Association (NFPA) in its 70E guidelines, classifies clothing into four categories based on the level of voltage being encountered by a technician. Based on the voltage used in EVs today, the minimum use of ARC 2 clothing when working on HV systems is required.

Most uniform suppliers offer clothing which meets the NFPA 70E ARC 2 rating. Check with the supplier to determine if existing clothing meets requirements or must be upgraded.

Prior to performing any repairs or work on energized HV systems, remove all jewelry, including watches, rings, necklaces, or any other metal objects on your person. Belt buckles under the right conditions can become a major conductor of electricity. Either remove the belt and its buckle, replace it with a plastic or non-conductive material, or cover it with an insulating material prior to entering the approach boundary of an energized HV system.

b. Safety Shoe Requirements

When working with HV, it is important that the servicing technician does not become a ground path for the electricity in the HV system.

To reduce this HV potential, technicians performing HV work are required to wear “electric hazard” (EH) rated footwear.

In recent years, the American Society for Testing and Materials (ASTM) updated it’s F2413-11 standard for work related footwear by creating an EH requirement. EH (electric hazard) rated footwear can be identified by the required label printed on the interior of the shoe or boot.

ASTM F2413-11 Label Definitions

o M / F – male or female

o I – toe impact resistance of up to 75 pounds

o Mt -protect metatarsal area of foot with an impact resistance of up to 75 lb.

o EH – provide electrical protection for up to 600 volts.

o PR - puncture resistant

EH rated footwear can have steel or composite toe protection. If steel is used, it must be encapsulated in a di-electric material to receive the EH safety rating.

c. Insulated Rubber and Leather Safety Gloves

Whenever work is to be performed on an energized HV system (includes test, deenergizing or energizing the system) insulated rubber gloves must be used along with protective outer leather gloves. The leather outer gloves protect the insulated rubber gloves from becoming damaged during repair processes.

OSHA has developed standards around the type of insulated rubber gloves to be used when working on electrical systems based on the voltage potential. Based on the voltage used in EVs,

As of today, the HV systems in commercial vehicles require the use of Class 0 insulated gloves, which are rated at 1,000 volts AC and 1,500 volts DC, when working on energized HV systems.

Class 0 Insulated Rubber Gloves

Outer Leather Glove Protectors

The rubber insulated gloves come in assorted colors and have a date stamp of manufacture and last time they were tested by a third party (red label). OSHA requires rubber insulated gloves to be evaluated periodically and prior to being placed into service. Glove manufacturers incorporate some form of production code or date coding to indicate the date of initial testing. Insulated rubber gloves cannot be placed into service if more than a year old without independent third-party testing. Once placed into service, the insulated gloves must be evaluated every six months and certified as being in good condition.

Under no circumstances are insulted rubber gloves to be used past their six-month certification date.

Many fleets choose to work with third parties to manage the testing and evaluation process for the insulated gloves. There are no requirements for the leather gloves to be tested other than they must be in good condition and provide the proper protection for the rubber insulated gloves.

In addition to the annual certification, insulated rubber gloves are to be visually inspected and evaluated prior to each use. To inspect the insulated rubber gloves, check the exterior of the glove for any knicks, cuts or discoloration in the glove, especially in the fingertip area. Once satisfied with the exterior, turn the gloves inside out and perform the same inspection on the interior of the glove. If damage to the glove is identified during the inspection, the gloves are not to be used and are to be disposed of immediately.

Remember that any cut or nick in the glove will reduce its insulating capability and become a pathway for current.

Once the visual inspection is completed, blow into the opening of the glove inflating it and quickly trap air in the glove by pinching off at the cuff opening. Apply pressure to the exterior of the glove and listen for any escaping air, especially in the fingertip area.

Example of How to Test Insulated Rubber Glove

Rubber insulated gloves must be evaluated each time prior to use.

If gloves are used then removed, they must be evaluated again before a technician places his/her hand in the glove. This means that if you remove the rubber insulated gloves to perform work, the gloves must be inspected and evaluated again before being used to insure they were not inadvertently damaged when being removed or not in use. A simple pin hole in an insulated glove can become a pathway for current leading to injury or death.

For a visual overview of how to inspect rubber insulated gloves, go to the following link

d. ARC Flash Faceguard, Safety Glasses, and Ear Plugs

When working on HV safety systems, ARC2 rated faceguard, safety glasses with side shields are required. Since an arc flash can generate very loud sounds at levels that can damage ear drums, ear plugs are also a required part of PPE.

An ARC 2 rated faceguard, standard safety glasses and ear plugs are required when working on testing, deenergizing and energizing HV systems.

e. Fluke 1577 Insulation and Multimeter (2-in-1), Or Equivalent

Due to the voltages used on the HV systems of EVs, an International Electrotechnical Commission (IEC) category three (CAT III) multimeter is required for testing. A CAT III multimeter is capable of measuring DC voltages of up to 1,000 volts.

It is important that multimeter test leads be inspected prior to each use to insure they are CAT III (1,000 volt rated) leads and are not damaged.

The Fluke 1577 is a CAT III multimeter with the added capability of performing Isolation Testing of the HV system. The Isolation Testing procedure will not be covered in this document as it is vehicle specific.

The most important use of the Fluke 1577 Multimeter is testing to confirm that the HV system has been deenergized prior to performing any work on any of its components.

The “test-measure-test” process must be used to verify that a HV system has been de-energized and is safe to begin repairs.

Each vehicle manufacturer will have a procedure for deenergizing its HV system, but it will involve removal or switching off the MSD(s). It is important to note that the HV system will require time to dissipate power from the system’s capacitators, refer to the specific OEM guidelines for the procedures.

It is recommended that once the MSDs are removed, disconnecting the HV batteries from the vehicle, technicians need to wait at least fifteen (15) minutes before testing the system for its status.

After the required fifteen-minute waiting time, the multimeter “test-measure-test” process, as outlined below, must be used to verify the HV system is safe to begin repair work.

Step 1 – Use a known good voltage source, such as 12v battery, to evaluate that the multimeter is in working condition. This is not a calibration test; this just confirms the multimeter is functioning properly.

Step 2 – Using proper PPE and vehicle manufacturer’s procedures check HV system voltage. Voltage must be less than three (3) volts before proceeding.

Step 3 – After verifying the HV system has been de-energized (less than 3 volts), test meter again using the same known good voltage source (12v battery) as used in step 1, to verify multi-meter is in good working condition.

The “test-measure-test” multimeter procedure is a verification that the HV system is deenergized and that the meter is in good working order. When it comes to technician safety, do not assume anything.

All HV system components are to be considered energized until it is verified, using a multimeter, that they have been deenergized.

Remember that when the vehicle’s HV system has been deenergized, the vehicle’s battery packs are isolated from the rest of the HV system but that they still contain active HV electric power. There is no way to “switch-off” the vehicle battery packs.

VI. Tooling Requirements

To protect the technician, and anyone else in the general area, certain tooling is required during the repair process for EVs.

a. Approach Boundary Barrier and Lockout-Tagout (LOTO) Procedures

OSHA and NFPA 70E regulations require a barrier to be placed around a vehicle anytime HV system repairs are performed. The barrier is to establish a boundary around the vehicle indicating that unauthorized (untrained) individuals are not allowed inside the boundary.

A boundary of at least five feet from all sides of the vehicle and that the boundary includes warning signs indicating an HV danger exists.

It is the repairing technician’s responsibility to enforce the approach boundary limits and not let anyone within the boundary while a HV danger exists. Minimize distractions within the approach boundary, as focus is the key to keeping everyone safe. Once the vehicle’s MSDs are removed or turned off, secured, and verified that the HV system is deenergized, the approach boundary can be taken down.

Approach Boundary Barrier Example

Once the MSDs have been removed or turned off, they must be secured to ensure that an unauthorized individual cannot inadvertently energize the vehicle while work is being performed. In cases where the MSDs are removed to de-energize the vehicle, the MSDs are to be stored under lock and key with only the repairing technician having access to the key(s).

For vehicles where the MSDs are turned off (switchable) to de-energize the vehicle, the MSD switch must be secured with a padlock and the key kept in the possession of the technician performing the repair work.

Removeable MSD Switchable MSD

b. Recue Stick

The purpose of the Rescue Stick is to rescue an individual that encounters an HV system or component and is not able to disengage themselves due to the effects of the electrical current. Under no circumstances should another individual contact the victim directly. By contacting the victim directly, without any insulated tools, the rescuer will become part of the circuit and will suffer the effects as the original victim. Any time an HV system of an EV is to be tested, energized or deenergized, a second individual must be present outside the approach boundary to use the Recue Stick, if needed.

Before any HV system work can begin, an insulated 6’ (minimum) Rescue Stick rated for 1,000 volts be in the general work area.

Example of Rescue Stick

c. Insulated Tool Kit

Insulated tools for performing work on an EV are different from the traditional insulated pliers and wire cutters used in 12v DC or 120v AC repair services, where only the handles are insulated and are unrated. Insulated tools for EV HV systems are certified to insulate the user up to 1,000v at temperatures ranging from -4 F to 158 F.

Only insulated tools are allowed within the approach boundary while HV system is energized.

The following markings are required on insulated tools.

  • The name of the manufacturer (trademark is allowed)

  • The type of the tool

  • The double-triangle symbol indicating it is insulated.

  • 1,000V symbol, indicating the maximum AC voltage of the tool’s rating (1,500 v DC)

  • The year the tool was manufactured.

  • The standard reference, including the year of the publication. If the tool does not allow the full reference and year, it must at a minimum appear on the packaging.

Example of Insulated Screwdriver Set

When purchasing insulated tools, be sure to look for all the appropriate listings to ensure a quality tool. Once a properly rated tool is obtained, a pre-use inspection should be performed, looking for any damage to the tool. The tool should also be cleaned as needed prior to its use as dirt or other contaminants can become an unintended pathway for current. Be sure to follow any manufacturer procedures to ensure that the tool is used within its ratings.

VII. Lifts

Most EVs are constructed around the HV battery packs for safety and their protection, in most cases they are mounted between the frame rials. Although it is uncommon, if a battery pack must be removed from a vehicle it is done from the underside.

Although each OEM has their own procedures for removing the battery packs, in most cases this will require the vehicle to be lifted in the air to begin the procedure. Once prepared for removal the vehicle will be lowered so the battery pack rests on a support table. Final disconnects are made and the vehicle is lifted again to separate the battery pack from the vehicle.

Lifts must be selected based on the amount of clearance they provide to allow the battery pack to be removed. For this reason, most EV OEMs for light and medium duty vehicles recommend a two-post configuration capable of listing up to 15,000 GVW. On heavy-duty vehicles, a four-post configuration which lifts at the wheel positions, are required.

Two post Lift for Light/Medium Duty EVs

Four post Lift for Heavy Duty EVs

VIII. Glossary of Terms

Amperage – amount of current being used of flowing in the system (Amps or A)

Alternating Current – type of current where the direction of flow of electricity switches back and forth (AC)

Approach Boundary – short for restricted approach boundary and is the limit for unqualified personnel to approach.

ARC 2 – a standard of clothing that is resistant to flash fires and can absorb eight calories of heat per centimeter squared.

ARC Flash – phenomenon where a flashover of electric current leaves its intended path and travels through the air to a ground

ASTM – American Society for Testing and Materials

CAT III Multimeter – is a classification of a multimeter that can measure up to 1,000 volts, required for EVs.

De-Energized – state of the HV system when battery packs are isolated by removal of MSD(s)

Direct Current – type of current where direction flows consistently (DC)

EH – marking for electrical hazard boots

Energized – state of the high voltage system when battery packs are connected and delivering power.

EV – a vehicle using electric energy as its main source of propulsion.

High Voltage – where voltage exceeds 30v AC or 60v DC.

ICE – a vehicle using an internal combustion engine (diesel or gasoline) as its main source of propulsion.

kWh – a measure of electrical energy equivalent to a power consumption of 1,000 watts for one hour

kV- a unit of measure of potential voltage equal to 1,000 volts

LOTO – Lock Out, Tag Out

mA- milliamperes (where voltage is measured at one-thousands of an amp of electrical current)

MSD – Manual Service Disconnect (switched or removable devices that isolate battery packs from rest of vehicle)

NFPA – National Fire Protection Association (develop regulations for working with electricity)

OHM – standard unit of electrical resistance

OSHA – Occupational Safety and Health Administration

PPE – personal protection equipment used to protect technician from injury.

Volt – standard measurement for potential electromotive pressure or force

Watt – a unit of electrical power equal to one amp under the pressure of one volt

Document References

· Federal Motor Carrier Safety Administration (FMCSA)

· National Fire Protection Association (NFPA) 70E Standards

· Occupational Safety and Health Administration (OSHA)

· American Society for Testing and Materials (ASTM) – F2412-11 Standard

· International Electromechanical Commission

· Automotive Service Excellence (ASE) - Electrified Propulsion Vehicles HV Electrical

Safety Standards

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