UK Power Networks / DSR 01 016
v11.0

How to Ensure Low Voltage Customers Have Correct Polarity and Phase Rotation

Owner
Name / Peter Vujanic
Title / Head of Health Safety and Environment
Signature
Date / 09 July 2018
Authoriser
Name / Dudley Sparks
Title / Operational Safety Manager
Signature
Date / 09 July 2018

This document forms part of the UK Power Networks Integrated Management System and compliance with its requirements is mandatory. Departure from these requirements may only be taken with the written approval of the above authoriser.

Revision Record
Version number / 11.0 / What has changed?
Additional words added to section 7.2 to clarify what to do if a cross polarity is discovered whilst working alone – in order to comply with the DSRs. DSR 01 016a (now v12.0) and DSR 01 016b (now v2.0) reviewed no changes.
Why has it changed?
A request for clarity from the business.
Date published / 10/07/2018
Next review date / 10/07/2021
Prepared by / N Saunders
Version number / 10.0 / What has changed?
Removal of the neutral and earth conductors is now allowed. Changes to Section 8 and the testing regime required. Removal of references to the LV Handbook. Some grammatical changes. Polarity check form altered (DSR 01 016a) Standard letter of disconnection added (DSR 01 016b).
Why has it changed?
Full review of document
Date published / 01/05/2016
Next review date / 01/05/2019
Prepared by / D. Milton
Version number / 9.0 / What has changed?
Rewording of 3rd paragraph of section 6.1 to improve clarity and “where practicable” added to first sentence of section 8.1. Form DSR 01 016a v1.0 has been reviewed, there are no changes (now v2.0).
Why has it changed?
Feedback on recently issued procedure.
Date published / 25/09/2015
Next review date / 19/03/2017
Prepared by / D. Milton
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Contents

1.0Introduction and Purpose

2.0Scope

3.0Objective

4.0References

5.0Testing Locations

6.0Instruments for checking supply

7.0Process

8.0Tests required

1.0Introduction and Purpose

Distribution Safety Rule 8.1.6 requires polarity to be checked at an appropriate point before connecting a new supply or reconnecting a supply following rearrangement of conductors.

Tests will be required following any work on the network which may affect the polarity of any supply. This includes installation of new or replacement underground or overhead circuits and transformers. During a fault situation (where possible) a comparison will be made of results before and after the work.

2.0Scope

All work within the UK Power Networks licensed area networks, including the replacement of underground or overhead circuits and transformer changes, which may affect the polarity of any supply being undertaken by UK Power Networks staff and their contractors.

This document does not address Polarity Testing for Metering Service Providers undertaking meter work on behalf of Suppliers, or any work undertaken by Independent Connection Providers who should adhere to their own Codes of Practice and Safe Systems of Work.

Tests detailed in this procedure and associated documents shall be carried out before supply is left connected or reconnected to a customer’s installation.

Where installations include non-metered supplies then the polarity checks should include checking the incoming supply to the cut-out and the customer’s isolation point.

3.0Objective

To ensure that customers receive the correct polarity and phase rotation and that all low voltage services provided by UK Power Networks comply with the Electricity, Safety, Quality and Continuity Regulations 2002 (ESQC Regulations).

To ensure that even if a mistake is made during our work that a customer is not supplied with reversed polarity.

4.0References

The Electricity Safety, Quality and Continuity Regulations 2002
Distribution Safety Rules / (Principally Section 8)
Engineering Recommendation G14 / Protective Multiple Earthing: Recommended Principles for Testing to Ensure Correct Polarity
UK Power Networks Jointing Manual / 2.4 – New harmonised phase colours and section 5.0
GOP15 / LV Operations including linking, fusing, switching and cut-outs
JLV03 / LV Jointing (Including Cable Identification, Stripping and Preparation)
DSR 01 016a / Polarity Record
DSR 01 016b / Customer Left Off Supply Due To Safety Issue
NOP 50 018 / Pre-Arranged Interruption Procedure
EDS 06-0004 / Earth fault loop impedance requirements
LV Operations Handbook / Section 5

5.0Testing Locations

Tests are to be carried out at a position that ensures that polarity, and where relevant rotation, is correct before supply is provided for the first time or permanently reconnected after work on the network.

All displaced conductors shall be clearly marked before being disconnected. Best practice is for the person marking the conductors should be available during re-connection to reduce the possibility of cross connection of the conductors.

A pole top service box, with clearly identified phase and neutral terminations, would also be an acceptable position for before and after tests, providing no work has been carried out on the customer’s side of the box.

For looped service changes it will be acceptable to complete tests at just one supply point, provided no cut out or neutral block changes have taken place.

5.1Examples of appropriate test location

For a transformer change, before and after tests at the transformer low voltage links or fuses, providing no work has taken place on the outgoing side of the fuses or links.

  • For work where all cables are live, phasing tests during jointing will normally be adequate.
  • For fault work, where before work tests are not always possible, a satisfactory test at two cut-outs downstream of the work will be sufficient. By checking at two locations there is an acceptably low risk of a reversed supply at both cut-outs which has been corrected in the meter tails, or on the customer’s installation. If there is only access to one customer then a check at the cut-out, meter and customer’s installation will provide the same standard of check.
  • Where mains work overhead or underground, not involving services, affects several customers it will be possible to confirm correct polarity and phasing without access to all cut-outs. It will be sufficient to carry out a before and after test at a cut-outmeter and customer’s installation beyond the point of work.
  • For mains work polarity tests should be completed after jointing through cores but before filling joint boxes, wherever this is possible. It is only necessary to remove all accessible cut-out fuses where core identification is in doubt.
  • For Overhead line replacement or repair of more than one conductor, only those services with access to the meter position will be re-connected, with the polarity tests being made upon reconnection.
  • Where access to the consumer unit is not available the supply will be left disconnected. The pre disconnection Polarity check form shall be available when completing the re-energisation checks and will record the test results.

An example letter where customers are left off supply following a planned shutdown is shown in NOP 50 018 Pre-Arranged Interruption Procedure.

Although a continuity tester may be used for core identification on dead cables, further polarity and phasing checks shall be made after the cable has been made live.

6.0Instruments for checking supply

  • Test lamp
  • Testoscope neon indicator
  • Voltstick live conductor indicator
  • Socket tester
  • Phase Rotation Indicator
  • Voltmeter

6.1Methods of Testing

Appropriate Personal Protective Equipment (PPE) must be used when removing and replacing cut-out fuses and when working near live terminals.

The first and last stage of any testing is to check that any testing device is working.

For all cut-outs both a test lamp and either a Voltstick or Testoscope (neon) should be used to check for reverse polarity and open circuit neutral. Do not rely on only one device. The user may prefer to use a Voltstick as the Testoscope requires gloves to be removed to provide a reliable return path. A Testoscope shall be used when a Voltstick does not give a reliable indication.

If a test lamp fails to light it should be checked against a known live source or with an approved test lamp tester. If a Testoscope or Voltstick fails to light it should be checked against a known live source.

A socket tester used on PME systems cannot detect a cross polarity on its own. Used with the correct tests it will confirm internal wiring.

The consumer unit shall be checked by using a Voltstick. This can be achieved by running the Voltstick along the consumer unit fuses.

At no point should the consumer unit be dismantled by the person completing these polarity checks. In the case of an iron clad consumer unit then a discussion with your line manager shall decide an appropriate method of testing polarity of the work.

7.0Process

7.1General

On completion all services and equipment shall comply with current Engineering Standards and Manuals.

On all planned work polarity and if relevant rotation tests shall be carried out before supply disconnection these shall be recorded on the polarity record form DSR 01 016a or an equivalent be it paper or electronicformat.

7.2 Incorrect Polarity– Incoming up to the customer consumer unit

When carrying out the pre disconnection tests, if a customer is found to be receiving incorrect polarity or phase rotationthe customer’s installation shall be isolated.If the operative is accompanied by another person as per DSR rule 8.5.4, all meter tails and any PME earth connections shall be removed from the cut out.

Where a person working alone discovers a cross polarity and there is imminent risk to life, consideration must be given to mitigating the danger appropriate to the circumstances. This may include evacuating the building;asking Control to make the incoming dead in order to remove the meter tails and PME earth connections;waiting on site for a 2nd person;removing fuses from the feeding s/s etc.

A Line manager shall be contacted before continuing with any further work. This report should include details of any cut out or meter seals, which should be retained for further investigation.

The Line Manager shall arrange for an electrician to complete further checks on the customer’s installation before re-energising the customer’s supply.

The craftsman shall not attempt to solve the problem on a customer’s installation.

Whenever possible, for 3 phase supplies test the rotation. Any nonstandard phase rotation shall be recorded on the job paperwork and also marked on site by means of a suitable temporary label. This label shall be removed following the after work tests. Existing phase rotation shall not be changed unless specifically required by the job instruction.

On completion of the tests the cut-out shall, where practicable, be sealedwith a blank cut-out fuse carrier.The customer neutral and earth connections shall be removed from the cut-out and shrouded.

Any incorrect polarity or phase rotation shall be reported to Airline.

7.3 Incorrect Polarity – Customer Wiring from the consumer unit

If incorrect polarity or rotation is found on the customer’s internal wiring then the customer must be informed and the supply shall, where practicable, be sealed with a blank cut-out fuse carrier.

In either case a notice giving the reasons for the de-energisation plus a copy of
Regulation 26 of the Electricity, Safety, Quality and Continuity Regulations 2002, which covers disconnections, shall be left with the customer. Refer to DSR 01 016b Observation/Disconnection letter

7.4Planned work

Where access is required to a premises, whoever organises the work shall follow
NOP 50 018 Pre-Arranged Interruption Procedure.

Where the required access to the cut-out, consumer unit, sockets is not available at the start of planned work a decision will be made by the Line Managerwhether to continue with the shutdown. Factors to consider will include the number of other customers that are affected, time of year, weather conditions. If work continues any customer that has not provided access to the cut-out, meter, consumer unit, shall be disconnected before any work that may affect the polarity or rotation of their individual supply.

7.5Fault work

Wherever possible the cut-out fuseor fuses of any consumer, where the polarity may be affected should be removed and if still live, the polarity, and where relevant rotation, checked before the work is carried out and recorded on the polarity check form. It is accepted that removal of all cut-out fuses is not always possible where a large number of customers are involved or where access is difficult, such as during the night. Refer to section 5.1 for examples.

8.0Tests required

8.1All supplies with meter and customer’s equipment connected

For any service connections, where practicable, there should be before and after testing at the cut-out (this is not possible for new connections). This is because of the risk of a double cross situation where a cross at the cut-out has been corrected by a second cross on the consumer’s installation testing will be required at the consumer’s switchgear and at two separate sockets.

Measuring the earth loop impedance and voltage before work will help determine the cause if poor readings are found after the work. The Earth Fault Loop Impedance readings shall comply with EDS 06-0004 (Earth Fault Loop Impedance Requirements).

EDS 06-0004 includes a flowchart to assist staff with the process and any remedial work to be completed.

Any non-standard cut-outs especially re-wireable types or those with a neutral link shall be changed. This will include any inverted/upside down cut outs.

Before alteration / renewal work starts complete the following and record using DSR 01 016a or an electronic equivalent (this may not be possible for fault work).

The following shall apply after the tests above have been completed:-

a)Isolate customers switchgear and generation if fitted

b)Check using approved voltstick on cut out fuse(s) and associated tails

c)Remove the cut-out fuse(s)

d)The customer neutral and earth connections shall be removed from the cut-out.

e)Test the polarity at the cut-out

f)Measure and record the earth loop impedance value

g)Measure and record the supply voltage(s)

h)For three phase supplies test for correct rotation at the cut-out

i)For all supplies affix phase identification label(s)

j)Where practicable, insert a blank sealed cut out fuse

k)For unmetered suppliespolarity shall be tested at the customer’s point ofisolation

After completion of the work

a)Test the polarity at the cut-out

b)Measure and record the earth loop impedance value

c)Measure and record the supply voltage(s)

d)For three phase supplies test the phase rotationat the cut-out.

e)Re-connect Neutral and Earth connections

f)Replace the cut-out fuses

g)Fit a harmonised wiring caution label where the meter tails are to different colour standards

h)Test for polarity on the incoming and outgoing sides of the meter

i)Turn on customers switchgear

j)Test for polarity at the customer’s switchgear using a voltstick

k)Where sockets are available use a Socket Tester in the cooker circuit and or two separate sockets.

l)If applicable test a 3 phase motor for correct rotation

m)Seal the cut-out and where known fit phase identification label(s)

n)Turn on customer generation if fitted

This printed document is valid at 01/05/16, check after this date for validity.
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