UL 1778
Uninterruptible Power Systems

Edition Number:5SCC Approved:--
Edition Date:2014-06-13DOD Approved: --
Price Code:DANSI Approved: 2017-10-10


    1.1 Scope

    Replace this clause of the RD with the following:

    1.1.1 Equipment covered by this Standard

    This Standard applies to UNINTERRUPTIBLE POWER SYSTEMS (UPS). The primary function of the UPS for this Standard is to ensure continuity of an alternating power source. The UNINTERRUPTIBLE POWER SYSTEM may also serve to improve the quality of the power source by keeping it within specified characteristics. This Standard is applicable to movable, stationary, fixed, and built-in UPS for distribution systems up to 600 V a.c. This equipment is designed to be installed in accordance with the Canadian Electrical Code, Part I, CSA C22.1, or the National Electrical Code, ANSI/NFPA 70, and, unless otherwise identified, the Standard for the Protection of Electronic Computer Data-Processing Equipment, ANSI/NFPA 75.

    This Standard specifies requirements intended to ensure safety for the OPERATOR and, where specifically stated, for SERVICE PERSONNEL.

    This Standard is intended to reduce the risk of fire, electric shock, or injury to persons from installed equipment, both as a single unit or as a system of interconnected units, subject to installing, operating, and maintaining the equipment in the manner prescribed by the manufacturer.

    1.1.2 Additional requirements

    In addition to the requirements in this Standard, a UPS is to comply with the UPS-relevant requirements of CAN/CSA-C22.2 No. 60950-1/UL 60950-1, March 2007, second edition, Information Technology Equipment – Safety –Part 1: General requirements (RD), as applicable for the country where the product will be used. Wherever there is a conflict between the requirements of this Standard and the RD, the requirements of this Standard will prevail.

    Engine-driven d.c. power generators intended to provide backup power for the battery supply circuit of UPS units are investigated for compliance with the requirements of UL 2200, and CSA C22.2 No. 100.

    UPS that employ hospital grade components identified by the markings "Hospital Only", "Hospital Grade”, or a green dot on the BODY of the component, or otherwise implying suitability for medical use, are evaluated to the requirements of this Standard and CAN/CSA-C22.2 No. 60601-1/UL 60601-1.

    Requirements additional to those specified in this Standard may be necessary for equipment intended for use where ingress of water is possible; for guidance on such requirements and on relevant testing, see Annex lll and Annex T/RD.

    1.1.3 Exclusions

    These requirements do not cover UPS units for use as legally required standby systems, described in Article 701 of the National Electrical Code, ANSI/NFPA 70, and emergency power supply described in Section 46 of the Canadian Electrical Code, Part I, CSA C22.1. See Annex lll.

    Where considered appropriate, revision of requirements will be proposed and adopted in conformance with the methods employed for development, revision, and implementation of this Standard.

    NOTE 1: For equipment subject to transient overvoltages exceeding those for Category II according to IEC 60664, additional protection might be necessary. Such additional protection may be located in the AC MAINS SUPPLY to the equipment or in the equipment as an integral design feature.

    NOTE 2 Where the additional protection is an integral part of the equipment insulation requirements, CREEPAGE DISTANCES and CLEARANCE distances from the mains through to the load side of the additional protection may be judged as Category III or IV as required. All insulation requirements, CREEPAGE DISTANCES, and CLEARANCE distances on the load side of the additional protection may be judged as Category I or II as required.

    1.1.4 Additional applications

    This Standard does not cover all types of UPS, but it may be taken as a guide for such equipment. Requirements additional to those specified in this Standard are in some cases necessary for specific applications, e.g.,

    a)    equipment intended for operation while exposed to conditions such as extremes of temperature; excessive dust, moisture, or vibration; flammable gases; or corrosive or explosive atmospheres;

    b)    UPS equipment based on rotary machinery;

    c)    UPS equipment meeting emergency lighting and power requirements as specified in UL 924; and central power system described in CSA C22.2 No 141-10.

    Additional subclause:

    1.1.101 Normative references

    Any undated reference to a code or standard appearing in the requirements of this Standard shall be interpreted as referring to the latest edition of that code or standard.

    Products covered by this Standard are to comply with the reference installation codes and standards as noted (in Annex iii) as appropriate for the country where the product is to be used. When the product is intended for use in more than one country, the product is to comply with the installation codes and standards for all countries where it is intended to be used.

    For products intended for use in Canada, general requirements are given in CAN/CSA-C22.2 No. 0.

    Expand All

    • Cover
    • Transmittal
    • UL Harmonized Standard Title Page
    • Table of Contents
      • Uninterruptible Power Systems
        • 1 General
          • 1.1 Scope
          • 1.2 Definitions
          • 1.3 General requirements
          • 1.4 General conditions for tests
          • 1.5 Components
          • 1.6 Power interface
          • 1.7 Markings and instructions
        • 2 Protection from hazards
          • 2.1 Protection from electric shock and energy hazards
          • 2.6 Provisions for earthing and bonding
          • 2.7 Overcurrent and earth fault protection in primary circuits
          • 2.8 Safety interlocks
          • 2.9 Electrical insulation
        • 3 Wiring, connections, and supply
          • 3.1 General
          • 3.4 Disconnection from the mains supply
          • 3.5 Interconnection of equipment
        • 4 Physical requirements
          • 4.1 Stability
          • 4.3 Design and construction
          • 4.5 Thermal requirements
          • 4.6 Openings in enclosures
        • 5 Electrical requirements and simulated abnormal conditions
          • 5.101 Short-circuit fault current withstand rating markings
          • 5.2 Electric strength
          • 5.3 Abnormal operating and fault conditions
        • 6 Connection to telecommunication networks
        • 7 Connection to cable distribution systems
    • Annexes
    • Annex AAA (normative)Additional component requirements
    • Annex BBB (informative)Examples of NORMAL LOAD conditions
    • Annex CCC (informative) Safety symbols and their meanings
    • Annex DDD (normative) Harmonic distortion test
    • Annex EEE (normative) Earthing and bonding(see .)
    • Annex FFF (normative) BACKFEED PROTECTION test
    • Annex GGG (informative) Principles of BACKFEED PROTECTION
    • Annex HHH (normative) Ventilation of battery compartments
    • Annex III (normative) Standards for components
    • Annex JJJ (normative) French translations and markings
    • Annex LLL(informative) Examples of US and Canadian regulatory requirements
    • Annex MMM(normative) Test and construction requirements for UPS with fault current ratings higher than those specified in Table
    • Annex NNN (normative) Short-circuit withstand rating
    • Annex OOO
    • Annex PPP(normative) Manufacturing and production tests