Siemens Mobility, Traffic Solutions
Sopers Lane, Poole, Dorset
BH17 7ER
Traffic Signal Junction Cabling
Design Certification for ELV Systems
Part no.
667/DS/20664/048
THIS DOCUMENT IS ELECTRONICALLY APPROVED
AND HELD IN THE TS DOCUMENT CONTROL TOOL
Issue
1
2
3
Change Ref
First issue
TS006376
TS006919
Date
October 2007
March 2012
April 2013
Company/Dept.
Name
Prepared By
Siemens Mobility, Traffic Solutions
Dave Brocklehurst
Checked and Released
Siemens Mobility, Traffic Solutions
David Martin
Function
Senior Product Engineer
Product Engineering Manager
March 16
March 16
Signature
Date
COPYRIGHT STATEMENT
The information contained herein is the property of Siemens plc. and is supplied without liability for errors
or omissions. No part may be reproduced or used except as authorised by contract or other written
permission. The copyright and the foregoing restriction on reproduction and use extend to all media in
which the information may be embodied
Copyright  Siemens plc 2016 All Rights Reserved
Version
Last Editor
Document
Name
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Dave Brocklehurst
533574419
Page i of 19
Status
Date
Doc. No.
Draft/Submitted/Issued
13 March 2013
667/DS/20664/048
Siemens Mobility, Traffic Solutions
Sopers Lane, Poole, Dorset
BH17 7ER
Siemens Mobility, Traffic Solutions,
Sopers Lane,
Poole,
Dorset,
BH17 7ER
SYSTEM/PROJECT/PRODUCT :
Site Reference:
Site Address:
Prepared By:
Function :
This Document is fully issued when this page is at a FULL numeric issue and all of the following
pages are at the same full numeric issue below and is either signed if provided in paper form, or has
the name of the person preparing it added above by the person who has edited the detail / designed
the junction cabling layout.
Issue :
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Date : dd/mm/yy
This is a published work the copyright in which vests in Siemens plc. All rights reserved.
The information contained herein is the property of Siemens plc. and is supplied without liability for
errors or omissions. No part may be reproduced or used except as authorised by contract or other
written permission. The copyright and the foregoing restriction on reproduction and use extend to all
media in which the information may be embodied.
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CONTENTS
1 ....INTRODUCTION .......................................................................................................... 4
1.1 .Purpose ........................................................................................................................ 4
1.2 .Scope ............................................................................................................................ 4
1.3 .Related Documents ...................................................................................................... 4
1.4 .Glossary ........................................................................................................................ 4
1.5 .Use ............................................................................................................................... 4
2 ....GENERAL NOTES ON INSTALLATION WIRING ....................................................... 4
2.1 .Neutral Connections (Ground Returns ELV) ................................................................ 4
2.1.1 Introduction............................................................................................................. 4
2.1.2 Context ................................................................................................................... 5
2.1.3 Procedure ............................................................................................................... 5
3 ....CABLING ...................................................................................................................... 5
3.1 .Cable Maximum Loading (Limited by the heating effect) ............................................. 5
3.2 .Loading limited by Cable Voltage Drop (thus associated with cable length) ................ 6
4 ....DUCTING ................................................................................................................... 11
4.1 .Capacities ................................................................................................................... 11
5 ....CABLE IMPEDANCES ............................................................................................... 13
5.1 .1mm2 Armoured Cable .............................................................................................. 14
5.2 .1.5mm2 Armoured Cable ........................................................................................... 14
6 ....COMPLETION OF VERIFICATION CALCULATIONS ............................................... 15
7 ....APPENDIX A VERIFICATION CALCULATIONS ....................................................... 16
8 ....APPENDIX B COMPLEX DUCTING CAPACITIES .................................................... 18
LAST PAGE ...................................................................................................................... 19
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1
INTRODUCTION
1.1
Purpose
This document is intended to allow an assessment to be made on the suitability of the cabling
design for an ELV traffic controlled junction installed by TS using TS provided cable. Providing all
of the criteria noted in the subsequent sections and sub sections are complied with within the
junction design, the cable and terminations design can be certified as complying with BS7671 and
Electrical Installation Certificates signed off.
1.2
Scope
This document only applies to cables 998/4/70468 and 4/MC832 supplied by TS, and cable
terminations supplied in TS traffic controllers and Pole Caps.
1.3
Related Documents
BS 7671
667/SA/20664/000
667/HE/20664/000
1.4
IEE wiring Regulations
Design and Manufacturer Supplied Information.
Installation and Commissioning Handbook
Glossary
ELV
1.5
Extra Low Voltage
Use
The tables in the body of the document allow a quick check of the electrical design. For a more
detailed check should one be required or if the values or extent of the tables are exceeded the
calculation form in the appendix should be used.
The process is to edit the data in this document for the particular customer / site and then
provide a paper or magnetic copy to the customer, who should then forward it on to the
appropriate installing company. To edit the forms in the appendices of this document, you
will need Microsoft Excel, double click on them and they will open up in Excel to allow
editing. When you have edited the data, click back on the body of the main word document
and the modified tables will be copied back to the word document. Then save the word
document in the normal way. Please remember to edit the document series number
picking a base number appropriate to your TS base i.e. DEPOT and selecting the next
variant in order. The site reference must also be edited in the footer to ensure each page
indicates the site for which it is relevant.
2
GENERAL NOTES ON INSTALLATION WIRING
The standard size of cable drum used in the field by TS is 250m; anything else is a special order.
TSs Recommendations are that ELV and detector cabling are run in separate ducts, where ever
possible.
2.1
Neutral Connections (Ground Returns ELV)
For the purpose of the following text, for ELV systems the ground return is considered in the
same way as a neutral return for a LV system.
2.1.1
Introduction
Street wiring faults can sometimes affect the display of traffic signals on-street. Poor connections,
for example in pole top termination blocks usually leads to the failure of signals to illuminate
properly which may be detected by lamp monitoring where this is implemented.
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2.1.2
Context
Where common neutral connections are used it is possible for the failure of a neutral connection
to cause unexpected signal displays, where one or more signals within a given signal head are
incorrectly illuminated simultaneously. This lack of neutral connection is not detectable by the
controller because the signal voltage presented at the controller terminals does not exceed the
required thresholds for conflict or correspondence monitoring.
When incandescent signals are used a cable fault of this type usually causes the signals to be
illuminated at a low level and is not particularly noticeable. For LED signals however it is possible
for the signals to flash, at least at their 'dim' level. Although the rate of signal flashing is such that
they are only typically illuminated for a very short time, less than the conflict / correspondence
time defined in TR2500, it can be more noticeable than the display seen with incandescent lamps.
2.1.3
Procedure
Normally this type of fault only affects a single signal head or pole and due to other signals
displaying correctly is unlikely to cause signalisations that could be considered dangerous, so
retrospective action is not essential.
Therefore we are not mandating retrospective action on existing sites, however if the customer
wishes to re-wire then we can do this on a chargeable basis
However for new LED sites where it is desired to reduce the likelihood of incorrect displays,
particularly involving green signals, it is recommended that individual neutral returns are used for
each green signal. For existing incandescent sites where LED signals are being now fitted and
spare cables cores are available these may be used to provide additional neutral connections.
3
3.1
CABLING
Cable Maximum Loading (Limited by the heating effect)
The ST900 ELV LSLS card supplies and monitors up to 8 off ELV signal head aspects, 8 off LED
Wait indicators, or 4 off TS Nearsides. The LSLS card can also supply 8 off Demand Indicators
The HPU card supplies and monitors up to 8 off ELV Reg Signs. It is therefore not necessary to
supply more than 8 off loads through one core, but the following information is shown for
completeness.
The following is based upon the worst case with all cores carrying the specified current and the
maximum number of any type of cable possible, i.e. the worst case condition (thus removing the
need to calculate all scenarios),whilst also taking into account the controller maximum load per
aspect drive. (See also LIMTS OF LOADING IMPOSED BY MAXIMUM DUCT CAPACITIES).
Provided that the loading per core is kept below the maximum number of heads / maximum
current value specified below, then the requirements of BS 7671 can be guaranteed. If loadings
above these are required then Engineering at Poole should be consulted. This later is extremely
unlikely.
LOADING
Core Size
Amps
ELV Reg
Signs
ELV Signal
Head Aspects
Red/Green
Nearsides
LED Wait and
Demand Indicators
1.00 mm2
1.50 mm2
3.5
4
24
27
14
16
9
10
24
27
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3.2
Loading limited by Cable Voltage Drop (thus associated with cable length)
The ST900 ELV lamp loads are shown below, and will be used to calculate maximum cable lengths.
Bright
48V
TS ELV Regulatory Sign
7W
TS Helios ELV (Vehicular or Far-Side Ped Signals)
12 W
TS CLS Wait Indicator (for Far-Side Ped Signals)
12 W
TS LED Wait Indicator (for Far-Side Ped Signals)
7W
TS Red/Green Nearside Signals
18 W
TS Ped Demand Indicator (for Near-Side Signals)
6W
ST900 ELV Lamp Load (Watts)
When estimating cable core and controller equipment requirements for the ST900 ELV Controller the
maximum cable lengths defined in the following tables must be complied with.
The voltage drop in the installation must be no more than 4% of the incoming supply. The tables should
be consulted to ensure that the voltage drop is lower than this maximum for the selected core size and
loading. If the voltage drop exceeds 4% the cores / conductors must be paralleled up to reduce it.
In addition the following guidance should be observed:
1. Where multiple cores are required due to long cable runs it must be noted that this may require
additional LSLS Outputs (and possibly an additional LSLS Card) in order to accommodate the
additional terminations in the LSLS Backplanes.
2. Where common ground return connections are used it is possible for the failure of a ground
return connection to cause unexpected signal displays, where one or more signals within a given
signal head are incorrectly illuminated simultaneously. This lack of ground return connection is not
detectable by the controller because the signal voltage presented at the controller terminals does
not exceed the required thresholds for conflict or correspondence monitoring.It is therefore
recommended that individual ground returns are used for each green signal.
3. The allowable lamp load per cable run is defined in the following tables. Refer to the above table
to determine the total lamp load connected to each drive cable and each return cable.
For each ‘out-going’ drive cable, determine the total load of all the signals supplied by that cable.
This will typically be a single aspect (e.g. one Helios ELV signal) but could be higher where a
green drive also powers a tactile unit for example.
A single LED signal return core (equivalent to the neutral in an LV system) is to be provided for
each Red, Amber, Green Signal (or Nearside Red / Green Signal). Where a common return core
is used, the highest lamp load that may be illuminated at any one time needs to be determined.
For a UK traffic signal head, one Helios ELV lamp load 12W is considered the highest for the
return cable since only one aspect is ever illuminated; the short red/amber period is ignored.
For a near-side pedestrian signal head, the figure is one near-side signal unless it shares the
same return with a Demand Indicator or a Tactile Unit.
Example, assuming a distance of 180 metres using 1.0mm 2 cable:

Near-side ped drive cables: 18W each at 180 metres = 2 cores (each)

Ped demand indicator drive cable: 6W at 180 metres = 1 core
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Siemens Mobility, Traffic Solutions
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
Common return cable: 24W (6W+18W) at 180 metres = 3 cores
4. If required to minimise core usage it is permissible to common signal returns on the same pole as
long as the total lamp load dependent on that return is considered and the cable length limitations
defined in the table are observed. For example, two 12W RAG traffic signal heads require that a
load of 24W is considered with a common return cable. (Note: please also consider the
comments given in paragraph 2)
5. Regulatory signs should normally be cabled with a separate drive and return core.
Where more than one regulatory sign is fitted to a pole, the drive and return for these may be
common, as long as total load dependent on those cables is considered and the cable length
limitations defined in the table are observed.
If required to minimise core usage it is permissible to common regulatory sign and traffic signal
returns on the same pole as long as the total load dependent on that return is considered and the
cable length limitations defined in the table are observed.
Example, assuming a distance of 100 metres using 1.0mm 2 cable:

Reg Sign supply cable: 7W at 100 metres = 1 core

RAG traffic signal drive cables: 12W at 100 metres = 1 core each (x3)

Common return cable: 19W (12W+7W) at 100 metres = 1 core minimum but 2 cores
recommended to allow an individual return for the green signal (see comments given in
paragraph 2 ) .
100 metres – 1.0mm2 cable
LSLS Card
12W RED DRIVE: 12W at 100m =1 CORE
R
A
AMBER DRIVE
: 12W at 100m =1 CORE
GREEN DRIVE
: 12W at 100m =1 CORE
G
GREEN RETURN
COMMON RETURN: (12W+7W) 19W at 100m = 1 CORE
HPU
REG SIGN SUPPLY: 7W at 100m = 1 CORE
It should be noted from looking at the table that above 100 metres, 2 cores would be required for
the 19W common return, and above 160 metres, 2 cores would also be required for each 12W
signal drive cable.
6. Tactile units are to be provided with a separate drive and return core. Tactile units driven from the
same phase green can share a common drive and return core. For the purposes of assessing
acceptable cable run lengths using the table, each tactile unit should be considered to be a 12W
load.
If required to reduce core usage, tactile units may share a return core with any LED signal return
core on the same pole. If this option is exercised each tactile should be considered to be a 45W
load for the purposes of assessing acceptable cable run lengths using the table. This figure is
much higher than their normal running power, but is typical of the power consumed if the tactile
device is physically held, stopping the motor.
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Siemens Mobility, Traffic Solutions
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7. The ELV solar cell should be provided with a drive and return core for connection of the solar cell
supply and signal. The solar cell return can be commoned with the LED signal return. Its effect on
the voltage drop is so small that it can be ignored.
8. Returns for digital inputs (for above ground detectors and pushbuttons etc on the same pole) may
be commoned together, but must remain separate from the LED signal returns.
9. Audible units must be provided with a separate drive and return core. Audible units on the same
Audible Driver Module may share a common drive and return core (up to 250m) if required to
reduce core usage, but must remain separate from the LED signal returns and digital input
returns.
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Note
NO MORE than 3 cores should be connected in parallel. The numbers in the cells within the tables indicate the number of cores required to meet
the voltage drop requirement.
10m
15m
20m
25m
30m
35m
40m
45m
50m
60m
70m
80m
90m
100m
110m
120m
130m
140m
160m
180m
200m
225m
250m
275m
300m
325m
350m
375m
400m
7W
10 W
12 W
18 W
20 W
25 W
30 W
35 W
40 W
45 W
50 W
60 W
80 W
100 W
120 W
5m
Lamp Load (Watts)
Length of Cable Run (metres) – 1.0 mm2 Cable
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
1
1
1
1
1
1
1
1
1
1
1
2
2
2
3
1
1
1
1
1
1
1
1
1
1
1
2
2
2
3
1
1
1
1
1
1
1
1
1
1
2
2
2
3
3
1
1
1
1
1
1
1
1
1
2
2
2
2
3
3
1
1
1
1
1
1
1
2
2
2
2
2
3
3
1
1
1
1
1
1
2
2
2
2
2
3
3
1
1
1
1
1
1
2
2
2
2
2
3
1
1
1
1
1
2
2
2
2
2
3
3
1
1
1
1
1
2
2
2
2
3
3
3
1
1
1
1
2
2
2
2
3
3
3
1
1
1
2
2
2
2
3
3
3
3
1
1
1
2
2
2
2
3
3
3
1
1
1
2
2
2
3
3
3
1
1
1
2
2
2
3
3
1
1
2
2
2
3
3
1
1
2
2
2
3
3
1
2
2
2
3
3
1
2
2
3
3
1
2
2
3
3
2
2
2
3
3
2
2
2
3
2
2
3
2
2
3
2
2
3
Table 1 – ST900 ELV Cable Lengths: 1.0mm2
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10m
15m
20m
25m
30m
35m
40m
45m
50m
60m
70m
80m
90m
100m
110m
120m
130m
140m
160m
180m
200m
225m
250m
275m
300m
325m
350m
375m
400m
7W
10 W
12 W
18 W
20 W
25 W
30 W
35 W
40 W
45 W
50 W
60 W
80 W
100 W
120 W
5m
Lamp Load (Watts)
Length of Cable Run (metres) – 1.5 mm2 Cable
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
1
1
1
1
1
1
1
1
1
1
1
2
2
2
3
1
1
1
1
1
1
1
1
1
2
2
2
2
3
3
1
1
1
1
1
1
1
1
2
2
2
2
3
3
1
1
1
1
1
1
1
2
2
2
2
2
3
3
1
1
1
1
1
1
1
2
2
2
2
2
3
1
1
1
1
1
1
2
2
2
2
2
3
3
1
1
1
1
1
1
2
2
2
2
2
3
1
1
1
1
1
2
2
2
2
2
3
3
1
1
1
1
1
2
2
2
2
3
3
3
1
1
1
1
2
2
2
2
3
3
3
1
1
1
2
2
2
2
3
3
3
3
1
1
1
2
2
2
2
3
3
3
1
1
1
2
2
2
3
3
3
1
1
1
2
2
3
3
3
1
1
2
2
2
3
3
1
1
2
2
2
3
3
1
2
2
2
3
3
1
2
2
3
3
3
1
2
2
3
3
1
2
2
3
3
Table 2 – ST900 ELV Cable Lengths: 1.5mm2
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4
4.1
DUCTING
Capacities
Based on BS 7671 ‘Selection and Erection’ Appendix A Cable capacities on conduit and trunking section e) the following tables and rule of thumb has
been produced.
Duct
Cable
Cores
50mm
50mm
50mm
50mm
Armoured
Armoured
Armoured
Armoured
8
12
16
20
Number of cables
allowed
3
2
1
1
50mm
50mm
50mm
50mm
Un Armoured
Un Armoured
Un Armoured
Un Armoured
8
12
16
20
4
3
2
2
100mm
100mm
100mm
100mm
Armoured
Armoured
Armoured
Armoured
8
12
16
20
13
8
7
6
100mm
100mm
100mm
100mm
Un Armoured
Un Armoured
Un Armoured
Un Armoured
8
12
16
20
19
13
11
10
It should be ensured that none of the conduits in the installation exceed these recommendations.
Ducts should not be over filled with a visual check of the above it would appear as a maximum of 50% filled.
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For Detector Feeder Cables the following applies
Duct
Cable
50mm
50mm
50mm
50mm
100mm
100mm
100mm
100mm
1 Pair Armoured
2 Pair Armoured
1 Pair Unarmoured
2 Pair Unarmoured
1 Pair Armoured
2 Pair Armoured
1 Pair Unarmoured
2 Pair Unarmoured
Number of cables
allowed
4
3
7
5
17
13
31
23
A mixture of cable sizes i.e. a number of cables in a duct with different numbers of cores in the cables, becomes complex calculation
(and appendix B can be used), however a rule of thumb without referring to the spreadsheet in appendix B, would be as follows
Cable Type
Armoured
Duct
50mm
Un Armoured
50mm
Armoured
100mm
Un Armoured
100mm
1 20 Core
+ 1 other lower size
Cable
+ 2 other lower size
Cable
+ 7 other lower size
Cable
+ 11 other lower size
Cable
1 16 Core
+ 1 equal or lower size
Cable
+ 2 equal or lower size
Cable
+ 7 equal or lower size
Cable
+ 11 equal or lower size
Cable
1 * 12 Core
+ 1 equal lower size
Cable
+ 2 equal lower size
Cable
+ 9 equal lower size
Cable
+ 14 equal lower size
Cable
NOTE some customers have there own requirements for DUCT capacities and these must be complied with on contracts with those customers, check
with customers and / or their requirements’ specifications.
An Example would be.
50mm ducts should have no more than 2 armoured cables or 4 non armoured cables. If used in combination in the duct it can be taken that an
armoured cable is equivalent to 2 non armoured.
100mm ducts should have no more than 5 armoured cables or 10 non armoured cables. If used in combination in the duct it can be taken that an
armoured cable is equivalent to 2 non armoured.
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Bend Radii in a Traffic Signal Junction Installation meet the requirements of IEE Regs On Site Guide, provided a) the conduits are not over filled (see
earlier paragraphs with reference to duct capacities and, b) standard ‘Slow bends’ are fitted in conduits (e.g. for 50mm conduits 350mm radius,
100mm conduit 450mm radius), or chambers are fitted at such bend points allowing cable minimum bend radii to be met.
Allowable bend Radii are
For Armoured cable min bend radius is 6 X Dia For Un Armoured Cable min bend radius is 4 X Dia
Cores
8
12
16
20
1 Pair
2 Pair
5
Armoured Cable
Diameter
15.4
18.6
20.2
21.1
13.5
15
Min Bend
93.00
112.00
122.00
127.00
81.00
90.00
Un-armoured Cable
Diameter
12.6
15.8
17.4
18.3
9.9
11.4
Min Bend
76.00
95.00
105.00
110.00
60.00
69.00
CABLE IMPEDANCES
The ELV system only requires an Earth Loop Impedance test to be done on the Mains electrical supply to the controller cabinet, and not on the supply
from the controller, which is less than 50VAC nominal. Consideration of ELI offers a degree of protection against an accidental short-circuit from a
third party’s mains supply. Any third party LV supply must be separated from the TS ELV supply in all instances; it is recommended that the
installation is entirely ELV.
The approporiate impedances below should be combined and added with the Ze (earth loop impedance at origin) supplied by the Electricity supply
authority or Local Authority. The combined value should not be greater than the required ELI value for a 10A fuse. Then, these values should be used
to cross check the Earth Loop Impedances measured during the testing of the installation. The tables assume 1 core used, at measured at 20˚C, this
allows comparison with the max values allowed in 667/HE/20664, as the max values have been reduced by the IEE regs ‘Rule of Thumb’, 0.8 to take
into account being measured at 20˚C. Note the impedances below are the loop of 1 core plus the armouring.
Site Reference
Issue 3
Page 13
Siemens Mobility, Traffic Solutions
Sopers Lane, Poole, Dorset
BH17 7ER
150
160
170
180
190
200
210
220
230
240
250
3.89
4.14
4.40
4.66
4.92
5.18
5.44
5.70
5.96
6.22
6.48
3.39
3.62
3.85
4.07
4.30
4.53
4.75
4.98
5.20
5.43
5.66
3.33
3.55
3.77
3.99
4.22
4.44
4.66
4.88
5.10
5.33
5.55
3.27
3.49
3.71
3.93
4.15
4.37
4.58
4.80
5.02
5.24
5.46
150
160
170
180
190
200
210
220
230
240
250
2.89
3.09
3.28
3.47
3.67
3.86
4.05
4.24
4.44
4.63
4.82
2.45
2.61
2.78
2.94
3.10
3.27
3.43
3.59
3.76
3.92
4.08
2.29
3.06
2.70
3.11
140
3.17
2.12
3.63
2.51
1.96
140
130
2.31
1.80
2.84
120
2.12
1.63
2.88
110
1.93
1.47
2.94
100
1.74
1.31
3.37
90
1.54
130
1.96
80
2.62
2.00
1.75
0.65
1.14
0.77
0.49
1.35
40
0.58
0.41
70
2.66
2.04
1.78
1.53
30
0.48
0.33
0.98
25
0.39
0.24
1.16
20
0.29
0.16
60
2.72
2.33
1.81
1.55
1.31
15
0.19
0.08
0.82
10
0.10
0.96
5
50
3.11
90
2.07
1.58
1.33
1.09
120
80
1.81
1.36
1.11
0.87
2.40
70
1.55
1.13
0.89
0.65
2.44
60
1.30
0.91
0.67
0.55
2.49
50
1.04
0.68
0.55
0.44
2.85
40
0.78
0.57
0.44
0.33
110
30
0.65
0.45
0.33
0.22
2.18
25
0.52
0.34
0.22
0.11
12
Number of Cores
in the cable
8
Page 14
Issue 3
Site Reference
2.22
20
0.39
0.23
0.11
20
2.26
15
0.26
0.11
16
2.59
10
0.13
12
100
5
8
Number of Cores
in the cable
1.5mm2 Armoured Cable
5.2
1mm2 Armoured Cable
5.1
Length of Cable Run
Length of Cable Run
Siemens Mobility, Traffic Solutions
Sopers Lane, Poole, Dorset
BH17 7ER
1.28
1.43
1.59
1.75
1.91
2.07
2.23
2.39
2.55
2.71
2.87
3.03
3.19
3.35
3.51
3.67
3.83
3.99
1.09
1.24
1.40
1.55
1.71
1.86
2.02
2.17
2.33
2.48
2.64
2.80
2.95
3.11
3.26
3.42
3.57
3.73
3.88
0.62
1.12
0.64
0.47
0.93
0.48
0.39
0.96
0.40
0.31
0.78
0.32
0.23
0.80
0.24
6
0.16
0.08
20
0.16
0.08
16
COMPLETION OF VERIFICATION CALCULATIONS
It is required that the Verification calculations sheet in appendix A is filled out for the longest cable run and the shortest cable run. Double Click
on the form (this will open it in EXCEL to allow editing), answer yes to macros. Once completed, Click back on the Word document page to save it
back to the Word document. Once completed, the sheets should be checked for the following. NB The TARGET ELI value given in the blank form is
that for use with a 10A fuse.
a)
b)
c)
Volt drop does not exceed max limit shown.
MAX ELI does not exceed target max ELI.
Minimum conductor size is less than the size of the cores used (The Steel wiring Armouring will also sufficient).
Note for all of the above extra cores may be used to assist in bringing the design within requirements (no more than 3 cores in parallel).
The completed sheets should be signed and filed with the design.
Site Reference
Issue 3
Page 15
Siemens Mobility, Traffic Solutions
Sopers Lane, Poole, Dorset
BH17 7ER
7
APPENDIX A VERIFICATION CALCULATIONS
Conductor Size
1.50
CABLE USED
giving at 20 Celcius core resistance of
giving at 20 Celcius armour resistance of
Number of Cores
1 mm
2
8
12.1 ohms per km
7.19 ohms per km
Note 1
VOLTAGE DROP
Cable run length is
Signal Load Watts
Return Load Watts
250 meters
12
Number of paralleled Signal cores
12
Number of paralleled Return cores
1 Note 2
1 Note 2
Volt Drop From first principles is equal to the formula expressed on the next line
((Supply core *current)+(Return core *current)) * (Length of run *(core resistance per KM *70C factor 1.20)/1000))
voltage drop first principles
using table 4D4B (IEE Regs BS7671)
1.815 Volts
1.813
Limit @ 48 votls 1.92
Note 3
MAXIMUM LOOP IMPDENCE CALCULATED
Ze declared by supplier ( or County Council)
Single Core
Zs
Zs
5.7775
5.1725
0.35 Ohms
temp 70 celcius
temp 20 celcius
Note 4
If a single core does not give a low enough impdence the use of up to 3 can be tried
n Cores
where
n=
1
5.7775
5.1725
Zs
Zs
temp 70 celcius
temp 20 celcius
Note 4
FAULT CURRENT (Maximum Earth loop impedence to achieve disconnect time)
TARGET i.e. Max loop impedence Limit for controller as defined in 667/HE/20664/000 iss 13
to disconnect within the 5 seconds required. IS ==
6.19
Note 5
(including rule of thumb reduction) for measurement at 20 celcius
Note - Values obtained during commissioning testing are the values against which the installation is accepted
MINIMUM CONDUCTOR SIZE (BASED ON FAULT CURRENT)
If
32.22168519 Amps
Minimum conductor size
=Square root of ( I squared * Time) / K=115
K
for standard PVC
Minimum conductor size =
0.626520682 mm2 cross sectional area
Based on 10 amp BS88 or equivalents used on ST800 and ST700 controllers and the disconnect times
banded for 0.1,0.2,0.4 and 5 secs according to the time/current curves
Prepared By Name……………………………..… Signature………………………………………………..
Job / Function: ………………………………………..
For and on behalf of Siemens plc, Trading As Siemens Traffic Controls (STC), Sopers Lane, Poole BH17 7ER
Issue History
1
Site Reference
Date?
Issue 3
Page 16
Note 6
Siemens Mobility, Traffic Solutions
Sopers Lane, Poole, Dorset
BH17 7ER
Notes on Design Certification:Note 1
Cabling and armouring impedances are based on worst case figures from TS cable suppliers.
Note 2
For the Voltage drop for the designed installation to be acceptable it should be less than 4% as noted in
section 525 of the IEE Regs BS7671. The calculations for voltage drop in this document are based on the
worst case current for the aspects used in the installation. The currents assume the maximum power ratings
shown in Section 3.2.
Note 3
As noted in Note 1 above the IEE Regs sets the voltage drop limit within an installation at 4% (section 525)
and the value highlighted in red (1.92 volts) is 4% of the nominal 48 volt supply.
Note 4
For the earth loop impedance of the design to be acceptable, the calculated Earth Loop impedance must be
less than the target impedance based on a 10A fused Mains supply, which is considered to be an appropriate
fuse value for a third party supply.
R1 Circuit Phase
Conductor Resistance
Ze Supply
Impedance Circuit
Earth Loop
Impedance =
Ze + R1 + R2
Short Circuit
R2 Circuit Protective Conductor
Resistance
In the IEE regs all earth loop impedance calculations are normalised to the likely measurement temperature of
20 Celcius (as this allows for comparison when measuring this value during the test and inspection phase of
an installation), hence the values calculated here are normalised to this same 20 celcius.
The figures calculated include the impedance as for the supply as given by the electricity board supplier, and
thus are higher by this same amount than the loop impedances given in section 5 of this document.
Note 5
For the earth loop impedance of the design to be acceptable, the calculated Earth Loop impedance must be
less than the target impedance based on a 10A fused Mains supply, which is considered to be an appropriate
fuse value for a third party supply.
Note 6
The minimum cross sectional area for a conductor is calculated as noted in the IEE regs 543-01-03, and
provided the conductor size in the cable used is greater than this calculated figure, this part of the design is
acceptable.
Site Reference
Issue 3
Page 17
Siemens Mobility, Traffic Solutions
Sopers Lane, Poole, Dorset
BH17 7ER
8
Duct
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
APPENDIX B COMPLEX DUCTING CAPACITIES
Detector Feeder
Armoured
Unarmoured
Armoured Unarmoured Allowed ?
Size
8 12 16 20
8 12 16 20 1 Pr 2 Pr 1 Pr 2 Pr
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
100
1
Site Reference
Issue 3
Page 18