TITLE:

ES&H Manual

 

DOCUMENT ID:

6230 Appendix T1

Determining Equipment Class and Work Modes

 

 

1.0          Purpose

 

The work rules for electronic equipment are dependent on both the equipment Class and the work Mode.  Training requirements and the necessity for Work Control Documents are determined by an evaluation of the Class and Mode.  The Class, Mode, and minimum work rules are determined based on the information in this Appendix.

 

2.0          Scope

 

Equipment Classes, Work Modes, and the associated work rules for each Class and Mode are detailed and defined within this appendix along with other general precautions.

 

3.0          Responsibilities

NOTE:           Management authority may be delegated at the discretion of the responsible manager.

 

3.1       Qualified Electronic Worker

·       Understand the equipment Class, as defined in this Appendix, of the equipment on which they work.

·       Understand the Modes of work as defined in this Appendix.

·       Follow the work rules for the equipment Class and work Mode for all assigned and authorized work.

 

3.2       Supervisor/Subcontracting Officer’s Technical Representative (SOTR)/Sponsor

·       Understand the equipment Class as defined in this Appendix, for the equipment.

·       Understand the work Modes as defined in this Appendix.

·       Ensure that workers assigned to electronic equipment work are trained, knowledgeable, and qualified for the work assigned to them.

·       Understand the requirements associated with each equipment Class and work Mode.

 

4.0          Process Steps

 

When work is performed on electronic equipment the equipment Class and the work Mode must be determined prior to doing any work.  Work rules based on Class and Mode, are established to mitigate the hazards due to exposure to electrical energy. 

 

4.1            Hazard Classes

The hazards associated with electronic equipment are divided into three Classes: (See Table 1 – Electronic Work Hazard Classes and Restrictions and Chart 1 – Electronic Equipment Hazard Classes)

·       Class 1 – Low Hazard

o   50 Vac or 60Vdc, 50 Amps

o   > 50 Vac or 60Vdc, 5 mAmps

·       Class 2 – Medium Hazard

o    50 Vac or 60Vdc,  > 50 Amps – Low voltage, high current

o    50 Vac or 60Vdc < V 250 Vac or 250Vdc, > 5 mAmps – Medium to high voltage, medium current

o   > 250 Vac or 250Vdc,  I 500 VA/Volt – Medium to high voltage, medium current

o   > 50 Vac or 60Vdc, >10 Joules Stored Energy – Medium to high stored energy

·       Class 3 – High Hazard

o   > 250 Vac or 250Vdc,  I > 500 VA/Volt – High voltage, high energy

 

4.2            Work Modes

Three work Modes are defined based on the type of work being performed, the extent of exposure of personnel to hazardous electrical energy and the consequent risk of injury.  (See Table 1 – Electronic Work Hazard Classes and Restrictions):

·       Mode 1 – Equipment De-energized

o   All work is conducted with the equipment completely de-energized and in an electrically safe condition. (Locked out in accordance with ES&H Manual Chapter 6110 Lock, Tag, Try (LTT) Program), and

o   Any stored energy is dissipated and any required grounding has been applied.

·       Mode 2 – Non-manipulative Diagnostics on Energized Equipment

o   Troubleshooting, measurements and diagnostics on or near energized conductors. Voltage testing (zero voltage checks) as part of Lock, Tag, and Try  when a Voltage Verification Unit is not present.

o   Protective barriers or covers are removed from energized components for access to equipment for the purpose of making measurements; and/or Personnel Protection Interlocks (on doors or covers) bypassed to allow access to components for measurements during powered operations.

·       Mode 3 – Manipulative Operations on Energized Equipment

o   Equipment is energized while circuit configuration is changed

o   Protective barriers or covers are removed from energized components for access to equipment for the purpose of making circuit alterations; and/or Personnel Protection Interlocks (on doors or covers) bypassed during powered operations to allow access to components for installation, removal, modification or repair of components.

 

4.3            Special Notes on Equipment Classes:

The following considerations and actions can affect the determination of the equipment Class.  These are addressed in work planning:

·       In equipment with multiple voltage and/or current capabilities, the equipment Class is determined by the highest voltage/current to which servicing personnel could be exposed during the work.

·       Exposure to the higher Class voltage/current portions of the equipment may be mitigated by the presence of insulating barriers (either original equipment or temporary), or shielding with dielectric properties suitable for the application.

o   e.g. – fully covered/insulated 120VAC input service to a low voltage electronics chassis may reduce the equipment classification from Class 2 to Class 1.

o   Temporary barriers must be secured in a manner to prevent accidental dislodging during work and they must be installed and removed under the appropriate Class and Mode work rules for the higher Class hazard.

·       Equipment containing energy storage devices (batteries, capacitors and inductors) that may have more than 10 joules of stored energy must be evaluated carefully in determining hazard classification.

 

4.4            Other Precautions

·       The specified work practices listed in Table 1 – Electronic Work Hazard Classes and Restrictions are minimum requirements.  Managers or supervisors may specify more restrictive procedures.

 

Table 1 – Electronic Work Hazard Classes and Restrictions

Work involving the primary circuit in electronic equipment must conform to the requirements outlined in ES&H Manual Chapter 6220 AC Electrical Equipment Safe Work Program.

Class 1 **

Voltage*

Current capacity

Hazard

Remarks

≤ 50 Vac or 60Vdc

≤ 50 A

Low

Low voltage, low power, low to medium current

> 50 Vac or 60Vdc

≤ 5 mA

High voltage, very low current

Mode 1

A qualified person may work alone.

Mode 2

A qualified person may work alone

Mode 3

If exposed voltages are less than 50 volts AC or 60 volts DC ( differential or to ground), a qualified person can work alone.  If greater than 50 volts AC or 60 volts DC, a qualified worker must be in the presence of another individual who can provide or summon assistance.

Class 2 **

Any of these

Voltage*

Current capacity

Hazard

Remarks

≤ 50 Vac or 60Vdc

> 50 A

Medium

Low voltage, high current

50 Vac or 60Vdc <V≤ 250Vac or 250Vdc

> 5 mA

Medium to high voltage and low/high current

> 250 Vac or 250Vdc

I ≤ 500 VA/V

high voltage, medium current

>50 Vac or 60Vdc, > 10 Joules

Medium to high energy stored

Mode 1

A qualified person may work alone.

Mode 2

At least two qualified persons are required.  They must be in continuous sight and sound communication.  A work control document approved by the AD and specifying PPE and shock/arc flash boundaries is required.

Mode 3

A work control document (e.g., SOP or OSP) must be used to describe how the work is to be accomplished safely.  An Energized Electrical Work Permit (EEWP) justifying why the work must be performed energized must be completed and approved by the Laboratory Director. The work supervisor must sign the procedure and provide direct supervision for the work.

Class 3 **

Voltage*

Current capacity

Hazard

Remarks

>250 Vac or 250 Vdc

I > 500 VA/V

High

DANGER – high voltage , high current

Mode 1

A qualified person may work alone.

Mode 2

At least two qualified persons are required.  They must be in continuous sight and sound communication.  A work control document approved by the AD and specifying PPE and shock/arc flash boundaries is required.

Mode 3

A work control document (e.g., SOP or OSP) must be used to describe how the work is to be accomplished safely.  An Energized Electrical Work Permit (EEWP) justifying why the work must be performed energized must be completed.  The work procedure and permit must be approved by the Laboratory Director for each occurrence of the work.  The work supervisor must sign the procedure and provide direct supervision for the work.

* Voltage is line-to-ground or line-to-line, whichever is higher.

** Class is determined by the highest voltage or current to which personnel may be exposed during servicing operations

 

Chart 1 – Electronic Equipment Hazard Classes

 

5.0          References

 

·       NFPA 70E - Standards for Electrical Safety in the Workplace

·       NFPA 70 - National Electric Code

·       OSHA Regulation 29 CFR 1910 Subpart S and 29 CFR 1926 Subpart K

·       DOE Electrical Safety Guidelines Handbook

 

6.0          Revision Summary

 

Periodic Review – 11/27/11 – No changes required at this time.  Minor edits to reflect current ES&H Manual format.

Revision 1 -12/10/08 – Update to reflect current laboratory operations.

 

 

 

ISSUING AUTHORITY

TECHNICAL POINT-OF-CONTACT

APPROVAL DATE

REVIEW REQUIRED DATE

REV.

 

 

ESH&Q Division

Bill Merz

12/10/08

12/10/14

1

 

This document is controlled as an on line file.  It may be printed but the print copy is not a controlled document.  It is the user’s responsibility to ensure that the document is the same revision as the current on line file.  This copy was printed on 1/7/2014.