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Cable Shield, Cable Gland, Fastener Torque Value, Sizing of Cable, Grounding System
Cable Shield as per ARAMCO & Internation Standard:
Prevent Electromagnetic Electrostatic Interference from being endued into the inner wire conductor.
Ø Design and installation of power and wiring system for instrumentation shall be in accordance with NFPA 70 and NEC.
Ø Fireproofing of cable in fire hazardous area shall be in accordance with SAES-B-006 (Aramco Standard).
Ø Shielded cables shall be used as required to reduce electrostatic noise. The shield shall be grounded at one point only.
Ø Field Bus Cable shall Comply with IEC 61158-2 (Type A)
Ø Cable Insulation thickness 0.38 mm PLTC/ITC
Ø TC Cable thickness 0.64 mm
Ø Light blue color coding shall be used to identify intrinsically safe wiring the preferred practice is to specify intrinsically safe interconnecting cable with blue outer jacket. Alternative blue sleeweves slipped over the jacket.
Ø At all the points of termination may used to identify I.S. wiring.
Ø If used for connections of equipment to ground rods or ground grid to be minimum 25 mm2 (# 4 AWG).
Ø Intrinsically safe system shall be used in zone 0 hazardous area.
Ø Thermal send have to use in trench before started send bedding.
Guide Lines to identify T/C and T/C Extension wires:
For Extension wires having insulation color as per ANSI MC96.1 (American National Standard Institute). The negative wire is always RED colored as per ANSI.
Cable Gland as per ARAMCO & Internation Standard:
Ø For Hazardous & Non Hazardous locations shall be in accordance with BS 6121 or BS 50262.
Ø Cable Gland: Cable glands are used to protect Mechanical damage. To give earth continuity and for
entering it a junction box & MCC etc. For PILC (Paper Insulation Copper Conductor) cables lead covered are used because in refinery, hydrocarbon gases will damage the PVC insulation, for this purpose lead cover is used, for these purpose plumbing type glands are used.
Ø In Explosion proof areas double compression glands are used to avoid these gasses entering in the electric at apparatus.
Fastener Torque Value:
M8 14 ~ 16 NM
M10 26~ 33 NM
M12 45~ 58 NM
Sizing of Cable as per ARAMCO & Internation Standard:
0.75 mm2 18AWG
1.0 mm2 17AWG
1.5 mm2 16AWG
2.5 mm2 14AWG
4.0 mm2 12AWG
6.0 mm2 10AWG
10 mm2 08AWG
16 mm2 05 AWG
25 mm2 04AWG
35 mm2 02 AWG
50 mm2 1/0AWG
70 mm2 2/0AWG
120 mm2 4/0AWG
Grounding System as per ARAMCO & Internation Standard:
Ø Ground rods 2.4 meter minimum length.
Ø Cathode protection material is used galvanized steel.
Ø Individual Ground rod maximum resistance should be 2.5 Ohm.
Ø For copper or copper jacketed steel rods is a minimum of 16 mm2 in diameter or 19 mm2 in diameters.
Ø Earth Tester is used for measuring of earthling system.
Ø Underground wire for grounding to wire connections shall be cadweld or thermoweld. Compression connector shall not be used.
Ø Shields wires shall be grounded only at the one point for the signal cables.
Ø Shields and armor of power cables shall be grounded at both ends.
Ø If used for connections of equipment to ground rods or ground grid be minimum 25 mm2 (# 4 AWG).
Ø Metallic cable trays shall be bonded at both end points and a minimum of every 25 Meter to the local ground grid.
Ø If buried / used for grids or interconnections of ground rods to be minimum 70 mm2 (2/0AWG).
Ø Be copper or copper jacketed steel or galvanized steel or copper jacketed steel shall meet the requirements of UL 476 (Underwriters Laboratories).
Ø Power Applications: Metal cable trays must be grounded and eclectically continuous systems as per NEC article 318.
Ø Non-Power Applications: Cable tray systems containing conductors outside the scope of NEC Article 250 (such as communications, data, signal cables, etc.)