Download DSR 01 007 Identification of High Voltage Cables

UK Power Networks
DSR 01 007
v6.0
Identification of High Voltage Cables
Owner
Name
Peter Vujanic
Title
Head of Health, Safety, and Environment
Signature
01 May 2016
Date
Authoriser
Name
Dudley Sparks
Title
Operational Safety Manager
Signature
01 May 2016
Date
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
6.0
Date published
01/05/2016
Next review date
01/05/2019
Prepared by
R Hembling
Version number
5.0
Date published
18/03/2015
Next review date
27/01/2018
Prepared by
R Hembling
Version number
4.1
Date published
15/05/2012
Next review date
27/01/2015
Prepared by
N Saunders
What has changed?
Document Owner name changed. DSR 01 015 Identification of Points of
Work added.
Why has it Changed?
Change of structure.
New procedure
What has changed?
Section 8.7 additional use of cable identifier in some circumstances when
tracing from a cable end box.
And additional example added to reasons not to spike.
Section 8.10 wording added to allow a second SAP to confirm that spiking is
the only option remaining
Section 8.11 wording change for clarity.
Section 8.13 I The word suspended removed
Why has it changed?
Variations to working practices
Feedback from Field operatives.
Actions from Incidents
What has changed?
Two sentences added to section 8.4 regarding the use of mobile phones
whilst identifying a cable using signal injection.
Why has it changed?
Field use Feedback
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Contract Manager/Users
Contents
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
11.0
Introduction and Purpose ............................................................................................ 3
Scope ............................................................................................................................. 3
Objective ....................................................................................................................... 3
References .................................................................................................................... 3
Definitions ..................................................................................................................... 3
Responsibilities ............................................................................................................ 4
Records ......................................................................................................................... 4
Process Detail ............................................................................................................... 4
Superseded Documents ............................................................................................. 11
Appendix A Identification of Cables by Signal Injection ...................................... 12
Appendix B Spiking Information............................................................................ 16
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1.0 Introduction and Purpose
This document gives the Approved procedure for identifying HV cables, the Approved
spiking procedure and other Approved means, which are required to comply with
DSR 5.9.2.
This document gives the approved procedure for moving a previously identified point of
work, to another position on the same cable (or circuit).
2.0 Scope
All operations in UK Power Networks Licence areas and on private networks that are
owned or managed by UK Power Networks.
If any field operative requires to use any other means, then the field operative must obtain
the consent of the Designated Engineer.
3.0 Objective
To prevent injury to any person who is to work on a High Voltage (HV) cable.
To prevent damage being caused to the network Plant and Apparatus.
To prevent the inadvertent interruption of electricity supply to customers
4.0 References
DSR
Distribution Safety Rules (Principally Rule 5.9.2)
DSR 01 018
Identification of LV cables
DSR 01 014
Excavating near electricity cables
DSR 01 015
Identification of Points of Work
HSS 40 029
Unidentified cables
Approved Instrument List
HSS 01 139
GTRA JHV 02
GTRA GOP 22
GTRA EHV 10
Maintenance of spiking guns and cartridge storage
HV Jointing (including cable identification, stripping and
preparation)
Identification of point of work and issuing of safety documents
EHV Jointing (including cable identification, stripping and
preparation)
5.0 Definitions
The use of a cartridge operated spiking gun, or other approved
device, which causes severe damage to the cable.
Spiking
A conventional cartridge operated spiking gun causes a metal
chisel to penetrate the cable, to cause the damage. The method in
which the spiking gun is used will depend on the type of cable
being spiked.
Hydraulic cutters are not to be used instead of a spiking gun.
Possible consequences of spiking an incorrectly identified cable are
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given in appendix B.
6.0 Responsibilities
It is the responsibility of all UK Power Networks employees and contractors working for UK
Power Networks, to comply with the requirements of this procedure.
In particular, it is the responsibility of the Senior Authorised Person (SAP) in charge of the
work, to correctly identify the HV cable and prove it Dead.
7.0 Records
There are no specific records.
8.0 Process Detail
8.1
General Requirements
Before any work is undertaken on a High Voltage (HV) underground cable that is a part of
the distribution network, then it shall first be made Dead, Isolated and Earthed in
accordance with the Distribution Safety Rules, identified at the point of work by an approved
method and proved Dead by approved means.
Where the work is to be carried out externally to the metallic Earth sheath (e.g. cathodic
protection bonds, insulating sheath repairs etc.), confirmatory spiking is not required.
However, it is essential that a Permit-to-Work (PTW) is issued by the Senior Authorised
Person. The points of Isolation and Earthing shall be recorded on the document and
Danger Notices posted on adjacent Live equipment.
8.2
Cable Records
Cable records give an indication of cable routes, type of construction and voltage. They
give no reliable indication of depth, as ground levels may have altered over the years, or a
cable’s position may have been changed by a third party without consent and not recorded.
They should be seen as providing a guide, rather than a detailed location plan for a specific
cable. Records should be used as a first step to locating and identifying a cable.
Cables may be encountered that cannot be identified by reference to cable records. These
may be private or abandoned cables that have not been recorded. In these circumstances,
the unidentified cable procedure HSS 40 029 should be followed.
8.3 Excavation of Joint Holes
Where there are other cables near to the cable to be identified, then any nearby relevant
cables (cables that cannot be reliably eliminated) must also be exposed. Signal injection
(see 8.4) may be used to identify the cable, in which case a comparison of the signal
strength on each cable and whether the signal strength varies as the detector is moved
around, or along the cables, will help to determine which cable has been injected with the
signal. Particular care is required when using a detector around rather than along a cable.
This is because any variations in signal strength may be due to changes in distance from a
nearby cable rather than due to the internal twisting of the cores of the cable.
If in doubt, seek advice from a SAP.
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8.4 Identification by Signal Injection
Signal Injection is the preferred method of cable identification. The cable shall be isolated
and earthed in accordance with DSR 4.1.1. A Sanction-for-Test (SFT) must then be issued.
The signal injection instrument (see approved instrument list) has two leads which must be
connected between two cores of the cable. This connection is made by the use of test
plugs, or integral test connections on switchgear (if available), or to an accessible cable
termination such as an overhead line, or cable sealing ends.
The person connecting the instrument must ensure that the connection points have been
effectively earthed to discharge all stored electrical charge, before they are approached or
touched.
The person conducting the test must consider if a second person is required during the
testing. This second person must be competent to avoid danger and must also understand
what is being done.
It is essential that the instrument leads are connected between two phase cores, so that the
signal does not find alternative earth paths and so reduce the possibility of an unwanted
signal on another cable.
The remote end of the cable will usually be in the earthed position. The earth will provide a
short circuit path between all phases.
On teed or multi-branch circuits, it may be necessary to remove and apply earths
appropriately, so as to be able to identify the correct Branch of the cable (see appendix A).
At the point of work, the signal shall be picked up by the use of a detector. If the detector is
moved around, or along, a conventional cable, the signal strength will vary due to the
internal twisting of the cores. This variation in signal strength will demonstrate that the
signal is in the cores and not in the earth sheath of the cable.
When possible, it is preferable to move the detector along the length of the cable, rather
than just around the circumference of the cable. Experience has shown that this normally
gives a better result, as the detector traverses a greater distance.
If the signal strength is constant, as the detector is moved around or along the cable, then
the cable may not be the correct one. Further tests and investigation will then be required.
If the cable is accessible at a location other than the joint hole, and its identity is known then
an instrument that induces a signal into the sheath of the cable may be used. The signal is
induced usually into the sheath of the cable by using a Current Transformer and a signal
detector is used to detect the signal at the point of work (see also 8.12).
The detector shall be used to listen for the presence or absence, of a signal on all the
exposed cables.
Be aware that a signal may be induced from mobile telephones into the listening device.
Switch OFF all mobile telephones when using this type of equipment.
Operatives using the signal equipment shall ensure that they are familiar with the
equipment and know how to use it correctly.
Following the identification of the cable by signal injection, the cable shall normally be
spiked (see 8.6).
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8.5
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Identification of Single Core Cable Circuits
The introduction of polymeric insulation has led to the wide spread use of single core
cables. These are mostly used in groups of three to form a circuit, instead of using a
composite three core cable.
Additional care is required when identifying circuits comprising of three single core cables,
when there are other nearby circuits which also comprise single core cables. There is
some possibility that the cores may have incorrectly been placed in groups of three, thereby
meaning that the group of three single core cables may not belong to the same circuit.
Even if the single core cables are in a duct, or have been tied together, the possibility may
still exist that they do not belong to the same circuit.
By attaching the signal injector leads to two phases, it is usually possible to determine
which two of the three single core polymeric cables have the strongest signal. By
disconnecting the signal injector lead from one of the phases and connecting it onto the
phase that was not previously injected, it will usually be possible to then identify the third
single core cable which previously did not have a signal. If the signal is weak or nonexistent in any of the three single core cables, it is possible that the cables have been
incorrectly grouped. Further tests and investigation will then need to be made.
8.6 Exceptions to Spiking a Cable
Exceptions to spiking a cable are restricted to the following work (and those detailed in the
following sections of this procedure):
Work on pressurised primary system cables that does not involve disturbing the
main insulation of the cable, for example:
a) sheath repairs;
b) temporary leak repairs;
c) repairs to apple wipes and band wipes;
d) removal of a fibre glass joint box or heat shrink sleeve for joint inspection;
e) freezing;
f) application of epoxy resin sheath reinforcement;
g) serving repairs on insulated sheath cables
h) removal of a ring of sheath to inspect and repair minor surface impact damage
on pressurised cables, where it is considered that a sleeve repair can be carried
out ;
(II) The complete break down and remake of a primary system pressurised joint to
carry out repair work.
(III) Exception to spiking primary system polymeric and paper solid cables is restricted
to the following work only:

topping up oil filled reservoir joints on paper cables.

serving repairs.
Where the work to be carried out is of the type described in this section and in the opinion
of the SAP it is safe not to spike, it will not be necessary to do so, provided the procedures
detailed below are complied with.
At the point of work the SAP will explain to the person who will receive the PTW how the
cable has been made dead and where it has been earthed. The SAP will then show that the
cable can be identified by reference to records. This will include reviewing any available
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circuit history accompanying the records, with particular attention being paid to any historic
work on a circuit and the impact this work might have had on the cable layout or joint
designations at the point of work.
The SAP will inject a signal into the cable and will listen at the point of work as required by
section 8.4. In addition where there are adjacent live circuits the listener should also be
used to confirm the absence of mains hum in the identified cable when compared with the
live cables.
Where (ii) above gives a very positive result, but is at variance with the records and this
cannot be explained then, where reasonably practicable, adjacent live cables should be
made dead. If this is not reasonably practicable and it is still considered safe not to spike
then a second SAP familiar with cable work will be required to visit site and satisfy
themselves that all precautions have been taken. The second SAP will confirm that they
agree that it is not necessary to spike the cable, and this will be written on the PTW. The
second SAP will endorse the issue of the PTW by signing alongside the person issuing the
PTW. This will be recorded with Control. Work on the cable will be started under the
personal supervision of both SAPs.
In any case where (i) and (ii) above give ambiguous results or cannot be complied with, or it
is considered unsafe to proceed without spiking, with the adjacent cables, then the adjacent
cables must be made dead, or the cable must be spiked.
8.7 Identification by cable tracing
It may be reasonably possible to trace a cable from a known Earthed position, such as:

A switchgear cable end box: Care is required due to the different layout of cable
boxes on switchgear especially that controlling Transformers and where reasonably
practicable the identification shall be confirmed by using signal injection.
 A cable sealing end
 An overhead line
The cable must be positively traced along its entire route from the known earthed position
to the point of work. A noose of non-conductive material shall be run from the known
Earthed termination, to the point of work. If it is not possible to use a running noose, then
another approved method must be used (e.g. signal injection).
When identifying a cable by cable tracing and the cable passes through a hole in a wall, it is
mandatory to run the noose through the hole. Tapping or tugging the cable, using rods, or
any other unapproved techniques are prohibited.
Where a cable passes through a duct line, it is prohibited to rod the duct as a method of
identification. There have been instances where this technique has failed in the past, when
the rod has passed from one duct line into another, so giving incorrect cable identification.
A cable that is identified at the point of work by positive tracing shall normally be spiked.
However, where the cable has been identified by positive tracing and the SAP has good
grounds not to spike the cable, then the cable need not be spiked.
Three typical examples of good grounds are:

A physical restriction or difficulty preventing the application of the spiking gun.

That the spiking of the cable would result in the need to extend the cable, so
producing additional work.
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Where the earth connection is clearly visible and the cable has been physically
traced from that earth.
8.8 Transformer Feeder Identification, by Signal Injection Method (HV/LV)
Where HV test access is not available, to simplify the procedure and avoid the necessity for
removing the lid of the distribution transformer, the test signal may be injected into the LV
winding, with an earth applied at the source end of the HV cable (see appendix A). Due to
the turns ratio of the transformer windings, the signal current produced in the HV cable will
be smaller than with direct injection but it is still normally adequate for identification
purposes.
A phase to phase connection for signal injection into the LV winding is preferable, although
a comparable signal level can be obtained by connecting between phase and neutral. (The
primary and secondary windings of the transformer are linked solely by electromagnetic
coupling and the presence of a single earth connection on each voltage system i.e. HV
cable earth and LV neutral earth connection, will not cause signal current to flow in the
cable sheath or via earth return paths).
It is imperative that the intended points of attachment of the signal injection leads are tested
before connection is made, to ensure that they are not Live.
Fused leads shall be used when being connected onto stalks of a LV distribution board.
8.9
Identifying a Spur (Pot / Stop Ended) HV Cable
Where work is required on a stop ended cable, such that signal injection cannot be utilised,
and it is also not possible to trace from a known earthed point, then cable records shall be
carefully consulted.
If the cable is accessible (and its identity known) at another location, then there are
instruments that are available that can induce a signal into the cable (usually the sheath). A
signal detector can then be used to see if the induced signal can be detected at the
required point of work.
If there are other cables present near the point of spiking, then identify the other cables so
that they can be eliminated.
Before spiking and under a SFT, connect a signal injection instrument to the cable cores.
Also check at the intended point of spiking with a detector, to see whether there is any form
of signal (there should be no detectable signal).
After the spiking, check for the presence of a signal in the cable, on the side of the spiking
gun to which the signal is being injected into the cable. The presence of a detectable signal
will indicate that the correct cable has been spiked.
8.10
Identifying Faulted HV Cables
Due to damage, it may not be possible to use signal injection to identify a HV cable which
has tripped on fault. The damage may have caused a high impedance fault, or an open
circuit fault, preventing the injection of a signal into the cable. In such cases, subject to an
on-site point of work assessment the use of the electrical discharge equipment that is used
to locate HV faults should be considered to identify the cable.
In this situation, the excavation in which the faulty cable has been exposed will need to be
guarded, whilst the discharge equipment is in use. In addition, the exposed point of fault or
damage must not be in contact with other cables; this is to prevent the electrical discharge
causing damage to adjacent healthy cables.
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If a clear unambiguous discharge is observed, this can be used as a means of positive
identification.
Once the cable has been identified by this method, the cable shall be spiked.
In the very rare case that a cable cannot be identified by signal injection or by using the
electrical discharge equipment mentioned above but it is believed that the cable in question
is the required cable (e.g. from consulting cable records), then an attempt to identify the
cable by inducing a signal into the cable, as described in 8.4 above shall be considered.
If all other approved identifying techniques have proved unsuccessful then a second SAP
familiar with cable work shall confirm there are no other alternatives. A cable identifier shall
be connected and with the consent of the Control Engineer the cable shall be spiked and
verified as per 8.13 below.
If there is a joint at this location, then the cable shall be spiked on both sides of the joint.
If the cable in question has been severed, then both sides of the severed cable shall be
spiked at a suitable position.
8.11
Identification of a HV Cable Terminating on a HV/LV Transformer
(HV Cable End Box)
If the HV cable to be identified terminates on the end box of a HV/LV transformer, then
provided the HV circuit has been disconnected (switched out deliberately) with a three
phase ganged device, it will be sufficient to prove the HV cable dead by testing for LV volts
before isolation and the absence of voltage on the LV transformer links or connections after
isolation
If a safety document is to be issued on the cable, then it shall be earthed in accordance
with the DSRs.
Where the HV protection is by independent fuses in the circuit, without an associated three
phase controlling switch, such as in a Fused Ring Switch, Fused End Box (FEB), pole
mounted drop out fuses, or Ring Disconnector Unit (RDU), this test will fail if two fuses have
ruptured, therefore unless a healthy circuit has been switched out deliberately, the cable
shall always be spiked.
8.12
HV Cable identification by induction
In exceptional circumstances the SAP may decide that it is not necessary to verify the cable
circuit being worked upon. This is typically when an induced signal (for example using a
Bauer instrument) has been used as a means of identifying the HV cable and will only be
acceptable in remote locations, where there is little chance of a second cable and the risk of
undertaking a verification outweighs the risk or working on the wrong cable (i.e. testing from
a pole at height). Before adopting this method consideration must be given to the possibility
of other cables, which may not be owned by UK Power Networks.
A CAT and Genny are not an acceptable method of cable identification.
8.13
Procedure for Spiking
Following the identification of a cable, the cable will then need to be spiked to ensure that it
is not Live at HV. The following procedure shall be followed:
a)
If the process has not already necessitated a Sanction-for-Test, then a SFT must be
obtained from Control (A SFT cannot be issued for idle or abandoned cables that
are not part of a network, as Circuit Main Earths cannot be applied).
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b)
If the cable has been identified by signal injection, it is not necessary to disconnect
the instrument and re-apply the Earth.
c)
The consent of the Control Engineer must be obtained prior to spiking.
d)
Spike the cable.
e)
Call Control and ask if any alarms have been received.
f)
Before the spiking gun is removed, at least one of the verification tests, given below,
must be conducted.
g)
Following a positive result of the verification test, the earths will be re-applied and
remain applied whilst the spiking gun is removed under the SFT and under the
Personal Supervision of the recipient of the SFT. (this does not preclude the option
of the SAP to issue a PTW to remove the spike gun)
h)
Furthermore, under the same SFT and following the removal of the spiking gun, the
cable may be opened and stripped for phase colour tests to be made under the
Personal Supervision of the recipient of the SFT (this does not preclude the option
for the SAP to issue a PTW to open and strip the cable).
i)
SFT to be cancelled and a Permit-to-Work shall be issued for work to commence on
the cable.
Injected Signal Strength Verification
Listen to the signal on either side of the spiking gun.
The signal strength on the side on which the signal is being injected should be distinctly
louder than that on the furthest side. This is because the spike driven into the cable
will be providing a short-circuit route for the signal. Therefore much less signal, if any,
will flow to the end of the cable where the circuit main earth has been applied.
Verification by Insulation (Megger) Testing
Prior to spiking, remove all the Earths and megger the cable. The cable can be tested
between phases and between phase to Earth.
The tests should show healthy insulation values.
After spiking, test the cable again. The results should show a faulty cable, thus proving
that the correct cable has been spiked.
Why Must Control be Contacted Before Spiking?
It is a requirement of DSR 5.9.2.
The consent of the Control Engineer must be obtained before spiking, to alert their
attention that an incorrect spiking may have occurred, if an alarm is received.
The Control Engineer also has a final opportunity to prevent the spiking, if a feeder trips
on the network in that vicinity. The circuit may be required to support the load and so
the job may have to be postponed.
Why Must Control be Contacted After Spiking?
It is a requirement of DSR 5.9.2.
The Control Engineer must be contacted after spiking, so that a check may be made
for any alarms that could be linked to the spiking. The Control Engineer may need to
check with other Control Engineers. This is because there have been occasions when
cables have been incorrectly spiked and the alarm has been received and accepted by
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another Control Engineer and not communicated to the Control Engineer dealing with
the cable spiking.
8.14
Spiking Requirements of Circuits Comprising of Single Core Cables
In normal circumstances the spiking gun should be applied such that all three cores are
spiked. However in the following circumstances it is essential that all three cores are
spiked:



11kV Networks with Arc Suppression Coils
11kV Networks fed from Unganged Fuses
Pot / Stop Ended Circuits
General
There may be occasions [excluding (i), (ii) or (iii) above] where it is only required to
work on one or two of the single core cables. It would therefore be undesirable to spike
and damage all three.
If only one or two of the single core cables are to be spiked, then insulation tests before
and after spiking shall be conducted, to confirm that the correct circuit has been spiked.
It will be necessary to use an instrument that applies a sufficiently high voltage, to
detect the damaged caused by the spiking. This is necessary, as the single core cables
may be completely severed by the spike and may appear as an open circuit (and
therefore healthy), if the voltage applied by the instrument is too low.
8.15
Re-location of point of work
Following the positive identification and spiking of a cable, it may be necessary to change
the point of work after issuing a Permit to Work e.g. when dampness testing. This may be
done, without reference to the Permit issuer, and without the need for further spiking,
provided that the Permit holder can physically trace the cable by means of a running noose
from the initial point of work, to the new point of work.
9.0 Superseded Documents
HSS 40 030
SEEBOARD Engineering Instruction EI 9/5/13
Eastern Electricity, Engineering Divisional Manual, System Operations, Identification of
dead HV cables, V12/S1/3.
HSS-406-OB-50
LPN Code of Practice 2.
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10.0 Appendix A
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Identification of Cables by Signal Injection
General
The following examples illustrate the methods to be adopted when identifying cables.
Although very simple circuits are shown, the principles apply to more complex circuits.
In the case of a trefoil group using polymeric single core cables, if there is more than one
circuit present, the test shall be repeated with the sender connections changed to a
different combination of cores, so as to prove that the three single core cables to be
worked upon, are part of the same circuit.
Plain Feeder
The signal injection device is connected to one end via test plugs, or test connections.
The other end of the cable is connected to Earth.
Sender
Point of Identification
R
Y
B
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Teed Feeder
It is necessary to perform at least two tests, preferably leaving the sender connected at
the same point throughout.
Sender
R
Y
B
Point of Identification
Test 1 Ensure no signal detected. Do not spike until the second test has been
completed.
Sender
R
Y
B
Point of Identification
Test 2 Detect signal then, after spiking, ensure signal disappears on earthed side of spike.
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Direct cable connection to a Distribution Transformer
Sender
Point of HV Cable Identification
R
Y
B
N
If it is not possible to make direct connection to the cable a signal may be injected
through a distribution transformer.
Remember that the LV may still be Live in part of the feeder pillar or cabinet.
Connecting the sender unit to a Live supply will cause serious damage.
Recommended Practice When Using Signal Injection
When the signal injection instrument has been connected to the circuit and the signal is
being injected, before leaving the point of injection (usually an item of switchgear), it is
good practice to use the signal detector at that point, to ensure that a satisfactory level of
signal is present in the cable. The opportunity can also be taken to listen to the
character of the signal, so that a comparison can be made later, at the point where the
cable is required to be identified.
At the intended point of work, where the cable is required to be identified, all cables must
be checked with the signal detector, as explained previously in section 8.4.
If no signal is detected on the exposed cable, or if the signal is very weak, the signal
detector can be used to check the ground below the cable, or the sides of the
excavation, to see if a signal can be detected from an unexposed cable. Even if a
satisfactory signal is detected on the expected cable, it is good practice to check the soil
in this manner, as this may give an indication of any cable carrying the signal, which has
not been exposed.
See diagram over the page
This printed document is valid at 29/04/17, check after this date for validity.
Page 14 of 17
UK Power Networks
DSR 01 007
v6.0
The diagram below gives guidance on the optimal position to use the signal detector, when
there are multiple three core cables present.
This printed document is valid at 29/04/17, check after this date for validity.
Page 15 of 17
UK Power Networks
11.0 Appendix B
DSR 01 007
v6.0
Spiking Information
Spiking guns may be used under the personal supervision of an Authorised Person, at
all fault levels and at all voltages up to and including 132kV. The manufacturer's
operating instructions shall be strictly observed, particularly the warning with regard to
the release of trapped gases before the removal of a spent cartridge. After use, the
equipment shall be inspected, cleaned and if necessary, maintained by a suitably trained
person In accordance with HSS 01 139.
The gun shall always be remotely fired by the use of the lanyard ensuring no one,
including third parties, are in the vicinity of the gun at the time of firing.
Clamping accessories are available to cater for the spiking of single core cables.
The clamp consists essentially of a parallel-sided slot in which the 3 cables to be spiked,
together with a short length of scrap cable of the same size and type, are placed in a 2
over 2 configuration. The additional short length of scrap cable is always placed in the
bottom of the slot. The parallel sides of the slot prevent the cables from moving apart
when the gun is fired and all four cable cores are penetrated.
The clamps are not restricted to use with single core polymeric cables and may be used
with three core cables, if one of the slots is of appropriate width for the cable to be
spiked. Some slight extra packing may however be needed under a three core cable, to
bring its upper surface to the correct level, so that the spike is fully retracted before
firing.
Cartridges are available in 4 grades of loading:Red Mark
(20 grain
Charge)
For armoured copper cables greater than 86mm
(16 grain
Charge)
For armoured copper cables up to 86mm
Silver Mark
(12 grain
Charge)
For 3 core Al/Polymeric cables and single core
Al/polymeric cables of 150 & 240 sq.mm. CSA.
Yellow Mark
(10 grain Charge)
For single core Al/Polymeric cables of 70 sq.mm.
CSA.
Green Mark
(3 3/8")0D.
(3 3/8")0D.
This printed document is valid at 29/04/17, check after this date for validity.
Page 16 of 17
UK Power Networks
DSR 01 007
v6.0
Cartridge Failure
If during the process of spiking the cable, the cartridge fails to fire, remain at a safe
distance for at least three minutes, before approaching the spiking gun to replace the
cartridge.
Consequences of an Incorrect Cable Spiking
In the event of incorrect cable identification, the following consequences may occur:
Incorrect Spiking of a Live HV Cable
The resultant damage will operate the source protection of the live cable and cause
an alarm to be sent to Control. If there is “downstream” protection on the HV feeder,
before the point of spiking, or if the cable belongs to another party, then it is
probable that no immediate information will be received at Control.
An incorrectly spiked HV cable, belonging to another party (such as an Independent
Distribution Network Operator) could be re-energised by that party, following its
initial spiking and consequential circuit tripping. This would result in serious danger.
It is therefore essential to obtain positive verification by an approved method, as
detailed in section 8.11, when identifying a cable by signal injection.
Incorrect Spiking of a Dead, Isolated or Abandoned HV or LV Cable
There would be no indication of an incorrect spiking. It should be appreciated that if
a spiked isolated cable was to be unknowingly energised, serious danger would
result.
Incorrect Spiking of a Live LV Cable
The spiking may not produce any observable signs (such as sparks, flames or
smoke) that the cable is live. It should be appreciated that after the spiking, the
cable could still be live on one or more phases which could also make the spiking
gun live.
In the event of the spiking of the wrong cable, the field operative shall not remove the
spiking gun. The Control Engineer shall be informed of the error and the Control
Engineer will give further instructions.
This printed document is valid at 29/04/17, check after this date for validity.
Page 17 of 17