This discussion is locked.
You cannot post a reply to this discussion. If you have a question start a new discussion

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
  • 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.

    Well, that is interesting ... and I think I disagree with an absolute ban on their use. Better to check with BOTH in a number of cases.

    Let me expand on this. Yes, I agree that a non-contact voltage indicator should not be the sole means of indicating absence of voltage (as per HSE Guidance Note GS38) ... BUT ... there are cases where touch current may be present, that a contact voltage instrument may not detect, but a non-contact detector (volt-stick) may detect.

    One example is with diverted Neutral currents ... see Appendix D to the 9th Ed (2022) of IET Guidance Note 3 Inspection and Testing, which multiple times recommends the use of a non-contact voltage detector, and gives the reason for this as "Voltage indicators do not detect diverted neutral currents while it is able to flow using an alternative path. A volt-stick should also be used."

    I don't believe there is such a thing as actually 'proving dead' (you can only amass evidence that a circuit is not energized, but I don't believe there is ever firm proof, simply because of the possibility of electromagnetic induction or capacitive coupling, and a human being completing the coupled circuit, if the source of inductive or capacitive coupling was inactive at the point of "proving dead" or the instruments used didn't permit the current to flow).

Reply
  • 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.

    Well, that is interesting ... and I think I disagree with an absolute ban on their use. Better to check with BOTH in a number of cases.

    Let me expand on this. Yes, I agree that a non-contact voltage indicator should not be the sole means of indicating absence of voltage (as per HSE Guidance Note GS38) ... BUT ... there are cases where touch current may be present, that a contact voltage instrument may not detect, but a non-contact detector (volt-stick) may detect.

    One example is with diverted Neutral currents ... see Appendix D to the 9th Ed (2022) of IET Guidance Note 3 Inspection and Testing, which multiple times recommends the use of a non-contact voltage detector, and gives the reason for this as "Voltage indicators do not detect diverted neutral currents while it is able to flow using an alternative path. A volt-stick should also be used."

    I don't believe there is such a thing as actually 'proving dead' (you can only amass evidence that a circuit is not energized, but I don't believe there is ever firm proof, simply because of the possibility of electromagnetic induction or capacitive coupling, and a human being completing the coupled circuit, if the source of inductive or capacitive coupling was inactive at the point of "proving dead" or the instruments used didn't permit the current to flow).

Children
No Data