 |
| Purchase Information |
| Use this form to request purchase information on UL online subscriptions. |
|
|
Document UL 1008 is offered by IHS as part of an online subscription. This subscription contains many documents on the same topic.
You may also purchase this document alone from the IHS Standards Store.
UL 1008 Document Information:
Title
UL Standard for Safety Transfer Switch Equipment
Underwriters Laboratories Inc.
Publication Date:
Nov 25, 1996
Scope:
These requirements cover automatic, non-automatic (manual), and
by-pass/isolation transfer switches intended for use in ordinary
locations to provide for lighting and power as follows:
Automatic transfer switches and by-pass/isolation switches for
use in emergency systems in accordance with Articles 517-Health
Care Facilities, 700-Emergency Systems, 701-Legally Required
Standby Systems, and 702-Optional Standby Systems of the National
Electrical Code, ANSI/NFPA 70 and the National Fire Protection
Association Standard for Health Care Facilities ANSI/NFPA 99.
Transfer switches for use in optional stand-by systems in
accordance with Article 702 of the National Electrical Code,
ANSI/NFPA 70.
In legally required stand-by systems in accordance with Article
701 of the National Electrical Code, ANSI/NFPA 70.
Automatic transfer switches and by-pass/isolation switches for
use in accordance with the National Fire Protection Association
Standard for Centrifugal Fire Pumps, ANSI/NFPA 20.
Non-Automatic transfer switches for use in accordance with
Articles 517-Health Care Facilities, and 702-Optional Standby
Systems of the National Electrical Code, ANSI/NFPA 70 and the
National Fire Protection Association Standard for Health Care
Facilities, ANSI/NFPA 99.
An automatic transfer switch for use in a legally required
stand–by system is identical to that used for an emergency
system.
These requirements cover transfer switch equipment rated at 6000
A or less and 600 V or less.
These requirements cover transfer switches together with their
associated control devices including voltage sensing relays,
frequency sensing relays, time delay relays, and the like.
An automatic transfer switch as covered by these requirements is
a device that automatically transfers a common load from a normal
supply to an alternate supply in the event of failure of the normal
supply, and automatically returns the load to the normal supply
when the normal supply is restored.
Exception: An automatic transfer switch is allowed to be
provided with a logic control circuit that inhibits automatic
operation of the device from either a normal to an alternate
supply, or from an alternate to a normal supply when the switch
reverts to automatic operation upon loss of power to the
load.
A non-automatic transfer switch as covered by these requirements
is a device, operated manually by a physical action, or
electrically by a remote control, for transferring a common load
between a normal and alternate supply.
A transfer switch may incorporate overcurrent protection for the
main power circuits.
These requirements cover completely enclosed transfer switches
and also open types intended for mounting in other equipment such
as switchboards.
Transfer switches are rated in amperes and are generally
considered to be acceptable for total system transfer, which
includes control of motors, electric-discharge lamps,
electric-heating loads, and tungsten-filament lamp loads as
referred to in 1.10.
A transfer switch intended for total system transfer as
indicated in 1.9 is considered to be acceptable for the control of
tungsten-filament lamp loads not exceeding 30 percent of the switch
ampere rating unless the switch has been investigated for a higher
percentage of lamp load and marked accordingly.
A transfer switch may be limited to use with one or more
specific types of load if investigated accordingly and marked as
indicated in 41.12.
These requirements also cover by-pass/isolation switches that
can be used to manually select an available power source to feed
load circuits and to provide for total isolation of an automatic
transfer switch. These switches may be completely enclosed,
enclosed with transfer switch or the open type intended for
mounting in other equipment.
These requirements also cover transfer switches and
bypass/isolation switches with an optional short-time current
rating if investigated accordingly and marked as indicated in
41.20.1. Short-time current is the maximum amount of fault current
a switch can withstand at a specified voltage for a given amount of
time and remain functional.
Deleted January 9, 2002
These requirements cover enclosed inlets intended to facilitate
connection of portable generators to transfer equipment.
About IHS
IHS (NYSE: IHS) is a leading global provider of critical technical information, decision-support tools and related services in a number of industries including aerospace and defense, automotive, construction, electronics, and energy. IHS serves customers ranging from large governments and multinational corporations to smaller companies and technical professionals in more than 100 countries. IHS been in business for more than 45 years and employ more than 2,300 people around the world.
