standard specification for erection tender - GAIL

a) Signals (4-20 mA or switch contact): 6/12 pair individually and over all shielded
(screened) and armoured, twisted, 0.5 mm conductor.
b) Thermocouple: 6/12 pair thermocouple extension cable (20 AWG)
c) RTD: 8 Triad 1.5 mm˜ conductor.
d) Solenoid valves (110 V DC): 6/12 Pair shielded, armoured, 1.5 mm˜ conductor.
Higher conductor size shall be selected to limit the voltage drop within the specified
limit.
2.22.2 The colour of outer sheath, inner sheath and individual core for each type of cable shall
be as mentioned below:
Type of cable Signal type Outer sheath Conductor Insulation
+ve -ve
a) signalIS blue blue * Black *
Non IS black blue * Black *
b) control/power black red Black
c) alarm IS, Non IS black white Black
d) extension IS As per IEC 60584-3
cable
• Triad cable shall have blue, black and brown colour.
2.23 Junction Boxes
2.23.1 Junction boxes shall be used for interconnection in the field wherever necessary
as per para 2.21.2. Analog signals (4 - 20 mA), switch contacts, temperature
elements, LEL detectors, intrinsically safe, non intrinsically safe and low voltage
contact signals shall be segregated in the separate junction boxes. Separate junction
box shall also be used for signals and contacts connected to PLC, DCS or and other
system.
2.23.2 The junction box shall be suitable for the type of signal and type of multi core
cables used as indicated in para 2.21.7. Unless otherwise specified, contractor must
use the following type of junction boxes:
For all intrinsically safe signals: Weatherproof junction boxes
For all input/output connected: Explosion proof/flameproof
to explosion proof/flameproof junction boxes instruments
2.23.3 The junction boxes shall have cable entries suitable for the multi and single
cables used. 20 % addition cable entries must be provided. Unused entries shall be
plugged.
2.23.4 The junction boxes shall have terminals suitable for the cable wire size and shall
preferably be of Phoenix or equivalent make. All junction boxes used in intrinsically
safe service shall be sky blue in colour while those in non-intrinsically safe service shall
be painted gray.
2.23.5 The multi cable entry for 6 pair Junction Box (JB) shall be 1" NPTF and for 12
pair / 8 triad junction box, it shall be 1 1/2" NPTF. Each junction box shall be provided
with 2 multi cable entries with one plugged with weatherproof, flameproof plug as
required. Multi cable entries shall be from the bottom whereas 1 pair/triad from the
STANDARD SPECIFICATION FOR
SPECIFICATION REV-0
GAIL (INDIA) LTD INSTRUMENTATION WORKS
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NEW DELHI
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