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ES&H Manual
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1.0
6230 Appendix T1
Determining Equipment Class and Work Modes
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
Individuals:
 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.
Personnel Assigning Work:
 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
Expectations/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.
ISSUING AUTHORITY
APPENDIX AUTHOR
APPROVAL DATE
EFFECTIVE DATE
EXPIRATION DATE
REV.
ESH&Q Division
Bill Merz
12/10/08
12/10/08
12/10/11
1
Page
1 of 6
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 5/4/2017.
ES&H Manual
TITLE:
DOCUMENT ID:
6230 Appendix T1
Determining Equipment Class and Work Modes
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 Volts, ≤ 50 Amps
o > 50 Volts, ≤ 5 mAmps
 Class 2 – Medium Hazard
o ≤ 50 Volts, > 50 Amps – Low voltage, high current
o 50 Volts < V ≤ 250 Volts, > 5 mAmps – Medium to high voltage,
medium current
o > 250 Volts, I ≤ 500 Watts/Volt – Medium to high voltage, medium
current
o > 50 Volts, >10 Joules Stored Energy – Medium to high stored energy
 Class 3 – High Hazard
o > 250 Volts, I > 500 Watts/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) Policy), 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.
ISSUING AUTHORITY
APPENDIX AUTHOR
APPROVAL DATE
EFFECTIVE DATE
EXPIRATION DATE
REV.
ESH&Q Division
Bill Merz
12/10/08
12/10/08
12/10/11
1
Page
2 of 6
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 5/4/2017.
ES&H Manual
TITLE:
6230 Appendix T1
Determining Equipment Class and Work Modes
DOCUMENT ID:

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.
ISSUING AUTHORITY
APPENDIX AUTHOR
APPROVAL DATE
EFFECTIVE DATE
EXPIRATION DATE
REV.
ESH&Q Division
Bill Merz
12/10/08
12/10/08
12/10/11
1
Page
3 of 6
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 5/4/2017.
ES&H Manual
TITLE:
DOCUMENT ID:
6230 Appendix T1
Determining Equipment Class and Work Modes
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 Policy.
Voltage*
Current capacity
Hazard
Remarks
Class 1
**
≤ 50 V
≤ 50 A
> 50 V
≤ 5 mA
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 differential or to ground, a qualified person can work alone. If greater
than 50 volts, a qualified worker must be in the presence of another individual who can provide or summon
assistance.
Any of
these
Class 2
**
Voltage*
Low
Current capacity
≤ 50 V
> 50 A
50 < V ≤ 250
> 5 mA
Hazard
High voltage, very low current
Remarks
Low voltage, high current
Medium
> 250 V
Low voltage, low power, low to medium current
I ≤ 500 watts/V
Medium to high voltage and medium/high
current
high voltage, medium current
>50 volts, > 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 a cognizant 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 EEWP approved by the Laboratory Director justifying why the work must be performed energized must be
completed. The work supervisor must sign the procedure and provide direct supervision for the work.
Class 3
**
Voltage*
>250 V
Current capacity
Hazard
I > 500 watts/V
High
Remarks
DANGER – high voltage , high current
Mode 1
At least two qualified persons must be present until it has been clearly verified that the equipment has been deenergized. Then, one qualified person may work alone.
Mode 2
At least two qualified persons are required. They must be in continuous sight and sound communication. Implied
approval and general supervision must exist. 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 Electrical Safety Work Permit 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.
ISSUING AUTHORITY
APPENDIX AUTHOR
APPROVAL DATE
EFFECTIVE DATE
EXPIRATION DATE
REV.
ESH&Q Division
Bill Merz
12/10/08
12/10/08
12/10/11
1
Page
4 of 6
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 5/4/2017.
ES&H Manual
TITLE:
DOCUMENT ID:
6230 Appendix T1
Determining Equipment Class and Work Modes
** 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
ISSUING AUTHORITY
APPENDIX AUTHOR
APPROVAL DATE
EFFECTIVE DATE
EXPIRATION DATE
REV.
ESH&Q Division
Bill Merz
12/10/08
12/10/08
12/10/11
1
Page
5 of 6
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 5/4/2017.
ES&H Manual
TITLE:
DOCUMENT ID:
6230 Appendix T1
Determining Equipment Class and Work Modes
ISSUING AUTHORITY
APPENDIX AUTHOR
APPROVAL DATE
EFFECTIVE DATE
EXPIRATION DATE
REV.
ESH&Q Division
Bill Merz
12/10/08
12/10/08
12/10/11
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 5/4/2017.
ISSUING AUTHORITY
APPENDIX AUTHOR
APPROVAL DATE
EFFECTIVE DATE
EXPIRATION DATE
REV.
ESH&Q Division
Bill Merz
12/10/08
12/10/08
12/10/11
1
Page
6 of 6
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 5/4/2017.