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TESTING FOR ABSENCE OF VOLTAGE

In the Project I am working on in Denmark for a global client, the North American Electrical Team are putting together a new bulletin on non-contact voltage testers and want EU to have their input (what do our Regs state).

I was wondering if the statement they are giving aligns with EU/UK standards and if so, can you identify a spec or section of the Regs, please?

Topic: NFPA 70E 120.5(7) TESTING FOR ABSENCE OF VOLTAGE

According to Article 100, an “Electrically Safe Work Condition” is a “state in which an electrical conductor or circuit part has been disconnected from energized
parts, locked/tagged in accordance with established standards, tested to verify the absence of voltage, and, if necessary, temporarily grounded for personnel
protection”.
NFPA 70E does NOT permit using a noncontact type tester (see image) when testing for the absence of voltage on electrical systems rated 1000 volts or less.
Section 120.5(7) specifically requires the absence of voltage test to be conducted from “phase-to-phase” and “phase-to-ground”. This type of testing cannot be
performed with a noncontact tester.
Section 120.5 provides guidelines on how to both establish and verify an electrically safe work condition. See below for more details on absence of voltage testing.
Below is a sample of NFPA 70E. For the complete section, see the actual NFPA
70E text at NFPA.ORG. Once there, click on the free access link to NFPA 70E.120.5
(7) Use an adequately rated portable test instrument to test each phase conductor or circuit part to verify it is deenergized. Test each phase conductor or circuit part both phase-to-phase and phase-to-ground. Before and after each test, determine that the test instrument is operating satisfactorily through verification on any known voltage source.
Exception No. 1: An adequately rated permanently mounted test device shall be permitted to be used to verify the absence of voltage of the conductors or circuit parts at the work location, provided it meets the all following requirements:
(1) It is permanently mounted and installed in accordance with the manufacturer’s instructions and tests the conductors and circuit parts at the point of work;
(2) It is listed and labeled for the purpose of verifying the absence of voltage;
(3) It tests each phase conductor or circuit part both phase-to-phase and phase-to-ground;
(4) The test device is verified as operating satisfactorily on any known voltage source before and after verifying the absence of voltage.
Exception No. 2: On electrical systems over 1000 volts, noncontact test instruments shall be permitted to be used to test each phase conductor.

Parents
  • I don't think non-contact voltage testers are mentioned in the wiring regs.

    They are mentioned in Electrical test equipment for use by electricians GS38 (hse.gov.uk)

    "13 Single-pole or non-contact live-circuit detectors sometimes referred to as ‘voltage sticks’ should only be used for identifying live equipment, not for proving that it is dead. There are particular requirements for the use of non-contact devices in coalmines. Only devices which make contact with the conductor (ie not proximity devices) should be used for proving dead. However, non-contact or proximity detectors can be useful in indicating if something is live, eg when attempting to remove a single cable installed in trunking containing many single cables"

    further info about working practices here Electricity at work: Safe working practices HSG85 (hse.gov.uk)

Reply
  • I don't think non-contact voltage testers are mentioned in the wiring regs.

    They are mentioned in Electrical test equipment for use by electricians GS38 (hse.gov.uk)

    "13 Single-pole or non-contact live-circuit detectors sometimes referred to as ‘voltage sticks’ should only be used for identifying live equipment, not for proving that it is dead. There are particular requirements for the use of non-contact devices in coalmines. Only devices which make contact with the conductor (ie not proximity devices) should be used for proving dead. However, non-contact or proximity detectors can be useful in indicating if something is live, eg when attempting to remove a single cable installed in trunking containing many single cables"

    further info about working practices here Electricity at work: Safe working practices HSG85 (hse.gov.uk)

Children
  • Yes OM, and it is very important to understand that whilst useful they depend on lots of assumptions, the biggest one is that one is testing a phase cable, but the neutral is still potentially dangerous! This may not show on these testers, they simply detect an electric field around a conductor, but essentially this is referred to Earth. This may sound strange, but if not every mains connected piece of Earthed metalwork would show live which is not the desired result! Contact dead measurements are essential for safety.