IEC 61892-5:2019

IEC 61892-5 ®
Edition 4.0 2019-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Mobile and fixed offshore units – Electrical installations –
Part 5: Mobile units
Unités mobiles et fixes en mer – Installations électriques –
Partie 5: Unités mobiles
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IEC 61892-5 ®
Edition 4.0 2019-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Mobile and fixed offshore units – Electrical installations –

Part 5: Mobile units
Unités mobiles et fixes en mer – Installations électriques –

Partie 5: Unités mobiles
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 47.020.60 ISBN 978-2-8322-6670-0

– 2 – IEC 61892-5:2019 © IEC 2019
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 8
3 Terms and definitions . 8
4 General requirements . 9
4.1 Environmental conditions . 9
4.1.1 Ambient temperature . 9
4.1.2 Relative humidity . 10
4.2 Protection against flooding . 10
4.3 Rotating machines . 10
4.4 Conductors, equipment and apparatus . 10
4.5 Main switchboards . 11
4.6 Handrails or handles on mobile units . 11
4.7 Axes of rotation . 11
5 Limits of inclination of the unit . 11
5.1 Authority requirement . 11
5.2 Machines, equipment and apparatus – General . 11
5.3 Propulsion machinery. 11
5.4 Essential source of power . 12
5.5 Emergency machinery . 12
5.6 Dynamic condition. 12
6 Bilge pumps. 12
6.1 Power supply . 12
6.2 Cables and cable connections. 12
6.3 Location of starting arrangement . 13
7 Navigation and obstruction lights . 13
7.1 General . 13
7.2 Obstruction lights when in operation . 13
7.3 Navigation lights . 13
7.4 Power supply and monitoring systems . 13
7.5 Special requirements for lights using LEDs . 14
8 Steering gear . 14
8.1 Power operated steering gear . 14
8.2 Motors . 14
8.3 Motor starters . 15
8.4 Power circuit supply . 15
8.5 Supply of control circuits and control systems . 15
8.6 Circuit protection . 15
8.7 Starting and stopping of motors for steering gear power units . 16
8.8 Steering gear control systems . 16
8.9 Alarms and indications . 16
8.10 Rudder angle indication . 17
8.11 Separation of circuits . 17
8.12 Communication between navigating bridge and steering gear compartment . 17

9 Electric propulsion . 17
10 Dynamic positioning . 17
11 Ballast systems . 18
11.1 General . 18
11.2 Ballast pumps . 18
11.3 Control and indicating systems . 18
11.4 Internal communication . 19
11.5 Protection against flooding . 19
12 Jacking systems . 20
12.1 General . 20
12.2 Design . 20
12.3 Holding capacity . 20
12.4 Electric motor capacity . 21
12.5 Jacking gear motors and motor controller. 21
12.5.1 General . 21
12.5.2 Group installation . 21
12.5.3 Overcurrent protection . 21
12.5.4 Running protection . 21
12.5.5 Monitoring . 21
12.6 Testing at factory at site or on board after modifications . 22
13 Anchoring systems . 22
13.1 General . 22
13.2 Anchoring arrangements . 22
13.3 Control systems . 22
13.4 Thruster-assisted anchoring systems (TA) . 23
Annex A (informative) Typical VSD driven AC jacking system . 24
Bibliography . 25

Figure A.1 – Typical VSD driven AC jacking system . 24

Table 1 – Ambient temperature . 10

– 4 – IEC 61892-5:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MOBILE AND FIXED OFFSHORE UNITS –
ELECTRICAL INSTALLATIONS –
Part 5: Mobile units
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61892-5 has been prepared by IEC technical committee 18:
Electrical installations of ships and of mobile and fixed offshore units.
The requirements specified in this International Standard are based on the Code for the
Construction and Equipment of Mobile Offshore Drilling Units (MODU Code) published by the
International Maritime Organization (IMO), and might include additional provisions.
This fourth edition cancels and replaces the third edition published in 2014. This edition
constitutes a technical revision.
This edition includes the following significant technical change with respect to the previous
edition:
a) the technical requirements as to electric propulsion have been replaced with a reference
to IEC 60092-501:2013;
b) the requirement for handrails on main and emergency switchboards has been added;
c) requirements as to control systems and indicators for watertight doors and hatch covers
have been made more specific;
d) requirements concerning the holding capacity for jacking systems have been rewritten;
e) requirements as to thruster-assisted mooring system have been rewritten;
f) the annex regarding enhanced system verification (HIL test) for dynamic positioned mobile
units has been relocated to IEC 61892-2:2019.
The text of this International Standard is based on the following documents:
FDIS Report on voting
18/1653/FDIS 18/1665/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all the parts in the IEC 61892 series, published under the general title Mobile and
fixed offshore units – Electrical installations, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 6 – IEC 61892-5:2019 © IEC 2019
INTRODUCTION
IEC 61892 forms a series of International Standards for safety in the design, selection,
installation, maintenance and use of electrical equipment for the generation, transmission,
storage, distribution and utilization of electrical energy for all purposes in offshore units which
are used for the purpose of exploration or exploitation of petroleum resources.
This part of IEC 61892 incorporates and coordinates, as far as possible, existing rules and
forms a code of interpretation, where applicable, of the requirements of the International
Maritime Organization (IMO), and constitutes a guide for future regulations which may be
prepared and a statement of practice for offshore unit owners, designers, installers and
appropriate organizations.
This document is based on solutions and methods which are in current use, but it is not
intended to impede development of new or improved techniques.
In this revision, voltage limitations have been removed. However, voltage limitations may be
given in the referenced equipment standards. The removal of voltage limitations is considered
necessary due to the interconnection of, and supply from shore to offshore units. In such
cases transmission voltages up to 132 kV AC and 150 kV DC are used and higher voltages
are being planned.
The IEC 61892 series aims to constitute a set of International Standards for the offshore
petroleum industry, but it is not intended to prevent their use beyond petroleum installations.

MOBILE AND FIXED OFFSHORE UNITS –
ELECTRICAL INSTALLATIONS –
Part 5: Mobile units
1 Scope
This part of IEC 61892 specifies additional characteristics for electrical installations in mobile
units.
It applies to installations that depend on buoyancy, such as column-stabilized units
(semi-submersible units), ship- or barge-type units as well as self-elevating units. It specifies
additional characteristics for such units, used during transfer from one location to another and
for drilling, production, accommodation, processing, storage and offloading purposes.
It applies to all installations, whether permanent, temporary, transportable or hand-held, to AC
installations and DC installations without any limitation on voltage level. Referenced
equipment standards may give voltage level limitations.
This document specifies requirements such as those concerning
– environmental conditions,
– limits of inclination for the unit where the equipment is required to operate,
– bilge pumps,
– navigation and obstruction lights,
– steering gear,
– ballast system,
– jacking systems, and
– anchoring systems.
For electric propulsion, reference is made to IEC 60092-501.
For dynamic positioning systems, reference is made to relevant IMO requirements.
This document does not apply to
– fixed equipment for medical purposes,
– electrical installations of tankers, and
– control of ignition sources other than those created by electrical equipment.
NOTE 1 For medical rooms, IEC 60364-7-710 provides specific requirements. Requirements for tankers are given
in IEC 60092-502.
NOTE 2 Guidance on protection of non-electrical equipment can be found in ISO 80079-36, ISO 80079-37 and
IMO 2009 MODU Code, 6.7.
NOTE 3 Attention is drawn to further requirements concerning electrical installations on such mobile offshore
units contained in the IMO MODU Code.

– 8 – IEC 61892-5:2019 © IEC 2019
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60034-1, Rotating electrical machines – Part 1: Rating and performance
IEC 60092-501:2013, Electrical installations in ships – Part 501: Special features – Electric
propulsion plant
IEC 61892-1, Mobile and fixed offshore units – Electrical installations – Part 1: General
requirements and conditions
IEC 61892-2:2019, Mobile and fixed offshore units – Electrical installations – Part 2: System
design
IEC 61892-3, Mobile and fixed offshore units – Electrical installations – Part 3: Equipment
IEC 61892-6, Mobile and fixed offshore units – Electrical installations – Part 6: Installation
IALA, Recommendation O-139 on The Marking of Man-Made Offshore Structures, 2013
IMO, Convention on the International Regulations for Preventing Collisions at Sea (COLREG)
IMO, MSC Circular 645, Guidelines for vessels with dynamic positioning systems, Annex
IMO, International Convention for the Safety of Life at Sea (SOLAS), consolidated edition
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61892-1,
IEC 61892-2, IEC 61892-3, IEC 61892-6, and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
auxiliary steering gear
equipment, other than any part of the main steering gear, necessary to steer the unit in the
event of failure of the main steering gear but not including the tiller, quadrant or components
serving the same purpose
3.2
dynamic positioning system
DP system
equipment necessary to provide means of controlling the position and heading of a mobile unit
within predetermined limits by means of resultant vectored thrust
Note 1 to entry: This note applies to the French language only.

3.3
electric steering gear
power operated steering gear where an electric motor applies torque to the rudder stock
through mechanical means only
3.4
electrohydraulic steering gear
power operated steering gear where a hydraulic pump, driven by an electric motor, applies
torque to the rudder stock through hydraulic and mechanical means
3.5
main steering gear
machinery, rudder actuators, steering gear power units and ancillary equipment and the
means of applying torque to the rudder stock (for example tiller or quadrant) necessary for
effecting movement of the rudder for the purpose of steering the unit under normal service
conditions
3.6
propulsion machinery
rotating machine normally intended to provide propulsive power
3.7
redundancy
existence, in an item, of more than one means for performing a required function
[SOURCE IEC 60050-351:2013, 351-42-28, modified – The definition has been reformulated
and the notes to entry have been deleted.]
3.8
steering gear control system
equipment by which orders are transmitted from the navigating bridge to the steering gear
power units
Note 1 to entry: Steering gear control systems comprise transmitters, receivers, hydraulic control pumps and their
associated motors, motor controllers, piping and cables, etc.
3.9
steering gear power unit
electric motor and its associated electrical and/or hydraulic equipment used to operate the
steering gear
4 General requirements
4.1 Environmental conditions
4.1.1 Ambient temperature
Unless otherwise given in the project specification, the values given in Table 1 are applicable.

– 10 – IEC 61892-5:2019 © IEC 2019
Table 1 – Ambient temperature
Minimum ambient air temperature for
continuous operation at rated capacity
Location
°C
Min. Max.
Engine rooms, boiler rooms, galleys and similar spaces, 0 +45
a
accommodation spaces
Open deck, dry cargo holds, steering gear compartments, −25 +45
deckhouses and similar spaces which are not provided with
space heating
Refrigerated chambers and holds, general The minimum temperature specified +45
for the unit, but not above −20
a
Components and systems shall be designed to operate at ambient temperature in the machinery space
between 0 °C and +55 °C (but not necessarily at rated capacity and continuous operation).

Where equipment is designed to operate with temperatures higher or lower than those stated
in Table 1, permissible temperature rises may be reduced or increased accordingly.
4.1.2 Relative humidity
Electrical equipment shall be designed for a relative humidity up to 95 %.
4.2 Protection against flooding
In every mobile unit, in which electric power is used for the services necessary for the safety
of the unit, the generators, switchgear, motors, energy storage devices and associated
controlgear for such services shall be so situated or arranged that the intended function of the
system is upheld in the event of partial flooding of the unit, within inclination limits referred to
in Clause 5.
The emergency services for the safety of personnel and the unit including emergency source
of power, switchgear, motors and associated controlgear for such services as well as
emergency control systems and communication systems should be located above the worst
damage waterline and be readily accessible.
For mobile and buoyant production units, the location of equipment as described above shall
be above the waterline that would exist if the unit was in a damaged condition, on or above
the uppermost continuous deck or equivalent and shall be readily accessible from the open
deck.
4.3 Rotating machines
Rotating machines shall be installed to minimise the effects of motion. The design of bearings
of all machines and the arrangement for their lubrication shall be adequate to withstand the
motions encountered in heavy weather and operation for prolonged periods at the list and trim
specified in Clause 5 without the spillage of oil.
4.4 Conductors, equipment and apparatus
Conductors, equipment and apparatus shall be placed at such a distance from each magnetic
compass or shall be so disposed that the interfering external magnetic field is negligible; that
is, the total singular deviation shall not exceed 30 min when any combination of circuits is
switched on and off.
4.5 Main switchboards
The main switchboard shall be subdivided into at least two parts. The subdivision may be
effected by circuit-breakers or other suitable means so that the main generators and any
supplies to duplicated services which are directly connected to the busbars are, as far as is
practicable, equally divided between the sections.
4.6 Handrails or handles on mobile units
Every main or emergency switchboard, generator control panel, UPS and relevant controlgear
required during stability damage or extreme motions shall be provided with a handrail, located
on a fixed part, or handles suitably fitted on the front of the switchboard. Where access to the
rear of above-mentioned switchboards is necessary for operational or maintenance purposes,
a handrail, located on a fixed part, or handles shall be fitted. It may be necessary to provide
handrails or handles for distribution boards if the dimensions are similar to main or emergency
switchboards.
4.7 Axes of rotation
For units where the requirements in relation to dynamic conditions as specified in 5.6 apply,
horizontal rotation machines shall, to the extent possible, be installed preferably with the shaft
in the fore-and-aft direction. Where a machine is installed athwartship, it shall be ensured that
the design of the bearings and the arrangements for lubrication are satisfactory to withstand
the rolling specified in Clause 5. The manufacturer shall be informed when a machine for
installation athwartship is ordered.
5 Limits of inclination of the unit
5.1 Authority requirement
Dependent upon the outcome of all studies relevant to the intact and damaged stability of the
unit, the appropriate authority may require or permit deviations from the angles stated in 5.2,
5.3 and 5.4.
5.2 Machines, equipment and apparatus – General
All machines, equipment and apparatus shall operate satisfactorily under all conditions with
the unit upright and when inclined up to the following angles from the normal, unless
otherwise required by the design basis for the unit in the agreed location:
a) for column stabilized units, 15° in any direction;
b) for self-elevating units, 10° in any direction;
c) for surface units, 15° either way in list and simultaneously trimmed 5° by the bow or stern.
NOTE The figures given in 5.2 are in accordance with the 2009 MODU Code.
5.3 Propulsion machinery
Main propulsion machinery and all auxiliary machinery essential to the propulsion and safety
of the mobile unit shall be capable of operating under the static conditions specified in 5.2 and
the following dynamic conditions, unless otherwise required by the design basis for the unit in
the agreed location:
a) for column stabilized units, 22° 30′ in any direction;
b) for self-elevating units, 15° in any direction;
c) for surface units, 22° 30′ rolling and simultaneously pitching 7° 30′ by the bow or stern.
NOTE The figures given in 5.3 are in accordance with the 2009 MODU Code.

– 12 – IEC 61892-5:2019 © IEC 2019
5.4 Essential source of power
The essential source of electrical power shall be designed to function at full rated power when
the unit is upright and when it is at any inclination up to a maximum angle as given in the
following a), b) and c), unless more stringent requirements are specified by the design study
for the unit:
a) column stabilized unit – from upright to an angle of inclination of 15° in any direction;
b) self-elevating units – from upright to an angle of 10° in any direction;
c) surface units – from upright and in level trim to an angle of inclination of 15° either way
and simultaneously trimmed up to 5° by the bow or stern.
NOTE The requirements are taken from the IMO 2009 MODU Code, 4.1.4. If the essential power source is also
being used for main propulsion, the requirements are given in 7.1.3 of the 2009 MODU Code.
5.5 Emergency machinery
Emergency machines, equipment and apparatus fitted in accordance with requirements of the
appropriate authority for emergency plants shall operate satisfactorily under all conditions
with the unit upright and when inclined, up to the following maximum angles from the normal:
a) for column stabilized units, 25° in any direction;
b) for self-elevating units, 15° in any direction;
c) for surface units, 22° 30′ about the longitudinal axis and/or when inclined 10° about the
transverse axis, unless otherwise required by the design basis for the unit in the agreed
location.
NOTE The figures given in 5.5 is in accordance with the 2009 MODU Code.
5.6 Dynamic condition
Where required by the appropriate authority, dynamic condition limits shall apply as follows:
a) rotation about fore-and-aft axis (rolling), ±22° 30′;
b) rotation about athwartship (pitching), ±7° 30′, unless otherwise required by the design
basis for the unit in the agreed location.
NOTE 1 The figures given in 5.6 are in accordance with the 2009 MODU Code.
NOTE 2 These motions can occur simultaneously.
6 Bilge pumps
6.1 Power supply
Motors of permanently installed emergency bilge pumps, if any, shall be connected to an
emergency switchboard.
6.2 Cables and cable connections
Cables and their connections to submersible pumps within the unit shall be capable of
operating under a head of water equal to their distance below the worst damaged condition
waterline. The cables shall either be armoured or mechanically protected by other means and
shall not be installed within the assumed extent of damage. They shall be installed in
continuous lengths from connection point located above the worst damaged condition
waterline to the motor terminals.

6.3 Location of starting arrangement
Under all circumstances, it shall be possible to start the motor of a permanently installed bilge
pump from a convenient point above the worst damaged condition waterline and in a space
not within the assumed extent of damage.
NOTE Information regarding the worst damaged condition waterline and the spaces within the assumed extent of
damage is given in IMO requirements, for example in the IMO MODU Code.
7 Navigation and obstruction lights
7.1 General
Except when a unit is stationary and engaged in operations, IMO COLREGs apply. These
regulations give for example requirements to the provision of primary and alternative lanterns
for each of the navigation lights.
7.2 Obstruction lights when in operation
When a unit is stationary and engaged in operations, attention is drawn to the requirements
for the safety of navigation of the coastal state in whose territorial sea or on whose
continental shelf the unit is operating.
Unless otherwise required by national authorities for obstruction lighting, the lighting shall be
in accordance with IALA Recommendation O-139.
7.3 Navigation lights
All units shall be provided with navigation lights which comprise masthead, side, stern, anchor,
not-under-command and, if applicable, special-purpose lights. The construction and
installation of navigation lights shall be to the satisfaction of the appropriate authority.
7.4 Power supply and monitoring systems
The following electrical arrangements relate only to the navigation lights referred to in 7.3.
a) Each light shall be connected by a separate cable to a distribution board reserved solely
for navigation lights, fitted in an accessible place under the control of watchkeeping
personnel.
b) There shall be two separate power supply systems to the distribution board, one being
from the main switchboard and one from the emergency switchboard. Where a transitional
source of emergency power is required by the IMO International Convention for the Safety
of Life at Sea (SOLAS), the arrangements shall enable the lights to be supplied from this
source in addition to the emergency switchboard. An alarm shall be activated in the event
of failure of a power supply to the distribution board.
c) As far as practicable, the arrangements should be such that a fire, a fault or mechanical
damage at any one point will not render both systems inoperative. It is, however, accepted
that the systems shall come together at some point where the changeover can be
performed. This should, preferably, be at or near the distribution board.
d) Each light shall be controlled and protected in each insulated pole by a switch and fuse or
by a circuit-breaker mounted in the distribution board.
e) Each light shall be provided with an automatic indicator to give an acoustic and/or optical
alarm in the event of complete extinction of the light. If an optical signal is used, which is
connected in series with the navigation light, means to prevent failure of the indicator
extinguishing the navigation light shall be provided. If an acoustic device alone is used, it
shall be connected to an independent source of supply, for example a battery, and
provision shall be made for testing this supply.

– 14 – IEC 61892-5:2019 © IEC 2019
The use of junction boxes in navigation light circuits, other than those provided for connecting
the lanterns to the fixed wiring of the electrical installation, should be avoided. Cables for
different circuits should not use the same junction box.
7.5 Special requirements for lights using LEDs
The luminous intensity of LEDs gradually decreases while the electricity consumption remains
unchanged. The rate of decrease of luminous intensity depends on the output of LEDs and
the temperatures of LEDs. To prevent a shortage of luminous intensity of LEDs, one of the
following solutions shall be used:
a) an alarm function shall be activated to notify the Officer of the Watch that the luminous
intensity of the light reduces below the level required by IMO COLREGs; or
b) LEDs shall only be used within the lifespan (practical term of validity) specified by the
manufacturer to maintain the necessary luminous intensity of LEDs; the lifespan of LEDs
should be determined and clearly notified by the manufacturer based on the appropriate
test results on the decrease of luminous intensity of the LEDs under various temperature
conditions and on the temperature condition of LEDs in the light during operation, taking
the appropriate margin into account.
The manufacturer of the navigation light should give information regarding lifespan (see b)
above) or detection of low illumination intensity.
NOTE Further information is given in EN 14744.
8 Steering gear
8.1 Power operated steering gear
8.1.1 Electric (including use of frequency converters) and/or electrohydraulic steering gear
shall be used for the power-operated main and auxiliary steering gear required by the
appropriate authorities.
8.1.2 The electrical systems of the main steering gear and auxiliary steering gear shall be
arranged in such a way that any failure in one of the steering gears will not render inoperative
the electrical systems of the other steering gear.
When an auxiliary steering gear is not required by the appropriate authorities and the main
steering gear comprises two or more power units, the electrical system for each power unit
shall be arranged in such a way that the failure of one of them will not render the other units
inoperative.
8.2 Motors
8.2.1 To determine the required characteristics of the electric motors for power units, the
breakaway torque and maximum working torque of the steering gear under all operating
conditions shall be used. The ratio of pull-out torque to rated torque shall be at least 1,6.
8.2.2 The rating shall be determined on the basis of the steering gear characteristics of the
subject unit as specified in 8.2.3 and 8.2.4.
Motors for steering gear power units may be rated for intermittent power demand.
8.2.3 For motors of electric steering gear power units, the rating shall be as follows:
S3 40 % in accordance with lEC 60034-1.

8.2.4 For motors of electrohydraulic steering gear power units and for converters, the
rating shall be as follows:
S6 25 % in accordance with IEC 60034-1.
8.3 Motor starters
Each electric motor of a main or auxiliary steering gear power unit shall be provided with its
own separate motor starter gear, located within the steering gear compartment.
8.4 Power circuit supply
8.4.1 Each electric or electrohydraulic steering gear comprising one or more power units
should, except as otherwise permitted by the appropriate authorities, be served by at least
two exclusive circuits, one fed directly from the main switchboard and the other supplied
through the emergency switchboard.
An auxiliary electric or electrohydraulic steering gear associated with a main electric or
electrohydraulic steering gear may be connected to one of the circuits supplying the main
steering gear.
The power supply system should be an IT system. For further information regarding IT
systems, see IEC 61892-2.
8.4.2 The circuits supplying an electric or electrohydraulic steering gear shall have a
continuous rating for supplying all electric motors and devices which can be simultaneously
connected to them and may be required to operate simultaneously.
8.4.3 For certain units specified by the appropriate authorities
...