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P.O. ENGINEERING DEPT.
ENGINEERING INSTRUCTIONS
LINES
OVERHEAD
E 3064
Issue 2, 2.5.38
WIRING
Regulation of Open Wires
1. General
The term "Regulation" may be defined as "The adjustment of the tension of
line-wires to a definite, chosen value". The tension can be decided only after
careful consideration of the influence of various factors, such as temperature,
elasticity of the wire, amount of dip, length of span and gauge of wire. To
simplify regulation, therefore, these factors have been co-related in the form
of Tables, which appear in E 3065, and which cater for the conditions most
frequently encountered in practice. The calculations underlying these tables are
detailed in E 1065.
NOTE:- For Regulation of Covered Wires, see E 3164.
2. Good regulation (by which is meant a close observance of the tensions as
tabulated, having due regard to the working temperature) is essential, and
greatly minimizes the difficulties of construction and maintenance.
3. Effects of faulty regulation
- Under-tensioning, i.e. the application of less than the correct tension,
obviously results in slack wires and increases the risk of faults due to
contacts.
- Over-tensioning will tend to strain the wires and fittings.
- Under-tensioning of one span followed by over-tensioning of the next,
will tend to pull the intervening pole out of line.
- Disregarding the working temperature - If regard is not paid to the need
for varying the tension according to the working temperature, then, at other
temperatures, wires which were not all erected at one time will assume
differing dips, and effects (a), (b) and (c) will be induced in varying
degrees.
TABLE 1
INSTRUMENTS AND TOOLS USED FOR REGULATING WIRES
4. Instruments and Tools used
It is quite impossible to adjust the tension of a wire to a given value by hand,
within the limits of error called for by good regulation. It is also unlikely
that the working temperature will be estimated accurately. Two instruments are
therefore provided, and are essential for good regulation, viz:- the Spring
Balance of the "Ratchet and Tongs, Nos. 1, 2 and 3" and the "Thermometer, No.
2".
5. Thermometer
This should be read at the commencement of each working day, and the necessary
wire tensions then determined by consulting the relevant regulation table.
During the day, and particularly in the summer when the temperature often varies
widely as the day proceeds, second and third readings should be taken; 11 a.m.
and 3 p.m. are suggested times. The thermometer should be read in a similar
position to that in which the wire is erected; i.e. in the shade if the wire is
in shadow, or in the full sun if the wire runs across open country.
6. "Ratchets and Tongs", "Tails, Insulated" and "Vices, Draw"
The salient points of these instruments and tools are brought out in Table 1,
and illustrated in Figs. 1 to 8.
FIG. 1
"RATCHETS AND TONGS, No. 1" FOR WIRE OF "300LB." PER MILE AND OVER
FIG. 2
"RATCHETS AND TONGS, No. 2" FOR WIRE OF 100-200LB. PER MILE
FIG. 3
"RATCHETS AND TONGS, No. 3" FOR "40LB." AND "70LB." WIRE
FIG. 4
"RATCHETS AND TONGS, NO. 4" FOR WIRE OF 100-200LB. PER MILE
FIG. 5
"RATCHETS AND TONGS NO. 5" FOR "40LB." AND "70LB." WIRE
FIG. 6
"VICE, DRAW, No. 2" USED FOR IRON WIRES OR STAY WIRES
FIG. 7
"TAILS, INSULATED"
FIG. 8
"KEYS, TENSION RATCHET" AND "KEYS, DRAW VICE, No. 2"
7. Notes on Tools
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"Ratchets and Tongs, No. 1" - These are supplied with
detachable jaws in pairs, so that they may be used with heavy wires of
different gauges. The relevant weight of wire, i.e. 300lb., 400lb., 600lb.,
or 800lb., is stamped on the jaws, which are readily fixed on to the Tongs
by means of the screws supplied with the tool.
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"Vice, Draw, No. 2" - This tool must not be used for copper
or cadmium-copper wires, since the vice-grip is liable to damage their
comparatively-soft surface. The vice should therefore only be used for
regulating iron wires, with which the danger of abrasion is not so great.
Since there is no spring tension indicator fitted to this tool, it follows
that it can only be used for iron wires which are regulated by eye, i.e.
those erected below existing wires whose tension has already been determined
by using "Ratchets and Tongs, Nos. 1 or 2".
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"Keys, Draw Vice, No. 2" - One end of this key fits the
spindle of the vice and the No. 1 ratchets; the other fits the wing-nut on
the draw-vice.
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"Tails, Insulated" - These are used so that either new or
existing wires may be regulated without causing interruption (e.g. due to
"earth" faults) to working circuits. Renewal of the flexible steel strand,
when necessary, may be done locally, using the items indicated in the
"Remarks" column of Table 1. Failure of the globe strain insulator or of the
scissors hook should be remedied by replacing the whole "Tail, Insulated".
8. Regulating the first "layer" of wires on a line
After paying out (see E 3055), the wire is first pulled up as tightly as
possible by hand and then regulated by means of the relevant tools, the wire
meanwhile resting on the intermediate arms on straight sections of line. At
curves in the line, the wire should be "clipped-in" to the insulator so that it
is free to move in the groove when tension is applied to the wire. The free end
of the " Tail, Insulated " is secured in the hole in the drum of the "Ratchet
and Tongs, No. 1, 2 or 3" and the scissors hook of the tail is then slipped
round the insulator spindle. The tongs are attached to the wire at a point about
4 ft. from the arm, and the wire is regulated to the requisite tension by
turning the ratchet drum, so coiling up the stranded steel wire of the tail and
drawing the tool and wire towards the arm. The wire is then terminated and
bound-in in accordance with E 3080 and E 3090. When tension is applied at the
binding-in point, the tool should be left in position until the next section has
been regulated.
NOTE:- If the first "layer" consists of two wires, "Ratchets and
Tongs, Nos. 1, 2 or 3" (which contain a tension indicator) will generally be
used. If there are more than two wires, it may be found necessary to use these
tools for the wires at the extreme right and left only, "Ratchets and Tongs,
Nos. 4, or 5" (which do not contain a tension indicator) being used for the
intervening wires.
9. Regulating wires which are erected subsequently to the first
"layer"
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New lines - When the tension of the wires in the first layer
has been determined by using "Ratchet and Tongs, Nos. 1, 2 or 3" the
remainder of the wires in the bed may be regulated by using either "Ratchet
and Tongs, Nos. 4 or 5" or "Vices, Draw, No. 2" (for iron wires). These
instruments do not contain a- tension indicator, and their use therefore
entails adjusting the dips of the wires to correspond with those of the
wires already regulated (but see para. 10). This may be done, for example,
by sighting, from the arm, two convenient similar points which coincide with
the point of maximum dip of the wires already regulated ; e.g., it may be
found that the top of the arm below, the point of maximum dip, and the top
of the corresponding arm at the other end of the span, are all in line for
the wires in the layer already regulated. Subsequent layers (except the
bottom one, below which there is no arm) may then be tensioned so that
corresponding alignment is observed.
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Existing lines - When wires are added to existing lines they
should be regulated to the same dip as the existing wires, as in (a) above,
unless the latter need re-regulation to ensure immunity from faults under
adverse weather conditions. When re-regulation is necessary it should be
carried out by the use of Ratchets and Tongs as in the case of new wires
(see para. 10), but steps should first be taken to ascertain whether the
slackness is due to the insecurity of one or more of the poles, arms, or
other fittings. In the event of the investigation revealing the need for
additional strengthening, pole resetting, arm straightening, etc., this work
should receive attention prior to the re-regulation of the wires.
10. Caution
When regulating a bed of new wires, they should all be regulated together to the
required tension before being terminated. If this is not done, the tension of
the first wires regulated will be affected by any movement of the pole due to
tension being applied to the remainder of the wires. Should this precaution
occasionally necessitate the use of more regulating tools than are normally
carried by a gang, an additional number should be requisitioned on loan prior to
the commencement of the work.
11. Pre-stretching wires
When regulating wires, an initial tension - equal to the tension specified in
the table for 20deg. Fahr. - should be applied momentarily. The tension should
then be reduced to the value specified in the appropriate regulation table. This
precaution not only takes out any bends in the wire, but somewhat equalizes
internal strains which may have been set up during manufacture.
P.O. ENGINEERING DEPT.
ENGINEERING INSTRUCTIONS
LINES
OVERHEAD
E 3164
Issue 1, 4.10.37
WIRING
Regulation of Insulated Line Wires (J. & P.B.J.)
1. General
The principles and general procedure relating to the regulation of open wires,
as laid down in E 3064, apply equally to covered wires; that Instruction should
be read therefore as appertaining alike to open and to covered wires,
particularly as regards:-
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the effects of faulty regulation,
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the impossibility of regulating by hand,
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the importance of using the thermometer,
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the necessity of regulating all new wires simultaneously,
and existing wires as and when new wires are added, and
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the pre-stretching of wire.
2. Tools
The tools used for the regulation of open wires are not all suitable for covered
wire, however, and must be adapted by certain additional methods not outlined in
E 3064. These and similar matters are dealt with in the present Instruction.
3. Regulating Tension
Covered wires should be regulated to the tensions specified in E 3165 (formerly
E 3155).
The following points should be borne in mind:-
a) Where covered Copper and Cadmium-Copper wires are erected on
the same line, the copper wires should be regulated in accordance with the
appropriate table and the Cadmium-Copper wires then drawn up so as to have the
same dip.
b) Where bare wires and covered wires are erected on the same line, the covered
wires should be confined to the lower arm positions and regulated as laid down
in para. 5, to the tensions specified in the relevant Table of E 3165 (formerly
E 3155). They must NOT be regulated to give the same dip as the bare wires,
since the tension then required would be greater than normal and their factor of
safety would be seriously reduced.
4. Tools and Instruments
The following tools and instruments, which are detailed in E 3064, are used with
covered wires:-
"Thermometer, No. 2" and "Cases, Wood"
"Ratchets and Tongs, No. 1" - used as they stand.
References:- E 3064, E 3165 (formerly E 3155) (Cnl)
Instructions Cancelled: T.I. XIII, para. 146
"Ratchets and Tongs, Nos. 2, 3, 4, 5" - used in conjunction with plaited "Tape,
Linen, Prepared" "Tails, Insulated, Large" and "Small"
"Keys, Draw Vice" and "Keys, Tension Ratchet"
5. Method of gripping Covered Wire, and appropriate tools
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For wire which weighs over 200lb. per mile "Ratchets and
Tongs, No. 1" are suitable. The jaws should be chosen so as to be
appropriate to the overall diameter of the wire, and not according to the
conductor weight as stamped on the jaws. When tensions not exceeding 170lb.
are to be applied, "Ratchets and Tongs, Nos. 2 and 4" may be used, but then
the wire must be gripped by plaited tape as described in (b).
-
For wire which weighs up to 200lb. per mile, "Ratchets and
Tongs, Nos. 2, 3, 4 or 5" may be used. The jaws of these tools are
unsuitable for gripping covered wire, however, since they would damage the
covering. The method to be adopted consists in plaiting a length of "Tape,
Linen, Prepared" for about 18in. near the end of the covered wire and then
applying tension to the free ends of the tape. The plaiting should be done
by laying the midpoint of the tape across the covered wire, and crossing and
re-crossing the ends over the wire and over each other with a "lay" of about
1½in. The ends of the tape should then
be tied to the ratchet.
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