The purpose of this procedure is to ensure that all works regarding electrical junction box and supports installation for electrical instrumentation works shall be done in accordance with the applicable local standards and all other applicable international codes and standards.
Scope of work covers the steps to be followed for the junction box and support installation for instrumentations intended for permanent installation in the project.
Field Junction Box (FJB) is a metallic/nonmetallic equipment used for connection of wires and cables which is installed in a designated area or outdoor.
Motor Control Junction Box (MCJB) is a junction box in which cables and wire for motor controls is being connected with.
Construction manager is responsible to plan and schedule activities for the installation and execution in co-ordination with client personnel.
Material engineer/coordinator is responsible to receive & visually inspect junction box and accessories, delivered on site before handing them over to client electrical/instrument department and shall be responsible for the safekeeping and preservation of materials received.
Every item delivered at project site shall be inspected to ensure compliance to specification, data sheet & free from damages.
When the unit is received at project site it shall be examined, inspected to ensure that it is free from any physical defects or damages.
Receipt of each package items shall be documented with details such as received date, type of parts or fittings, quantity, and avoid loss of parts during storage.
Offloading shall be in responsible & safe manner.
It is the responsibility of the QC inspector to carry out routine inspections, check the physical condition of the JB boxes before installation, any damages found must be reported immediately.
Health and Safety Requirements
Safe work permit requirement is mandatory.
All personnel involved in the electrical junction box installation activities shall wear complete personal protective equipment’s (PPE) in accordance with the safe work requirements.
Conduct job safety tool box before starting the work, and issue daily JSA.
Project safety officer shall verify that all the necessary and applicable documents, related to the safe operation are in possession before commencing the installation job.
Place barricade and warning sign boards in applicable locations.
Restrict Personnel/equipment’s entering the work area.
Check adequacy and availability of all tools, before commencement of installation activity.
If the weather conditions turns bad, (like sand storms, wind storms raining or hailstorms) shall immediately coordinate to safety officer and all works shall be stopped.
All the applicable health and safety procedures shall be followed at all times.
Project QA/QC Requirements
The Quality Control Program shall be as per project quality plan/procedure.
Detailed inspection stages and methods shall be as per the approved Inspection and Test Plan i.e. ITP.
Prior to commencing the installation work, the Instrument JB shall be inspected visually for any damages during the transportation.
All installed instrument JB shall be inspected for elevation as per the IFC drawings.
Inspection and test plan must be submitted ahead of time for consultant/client approval.
Preparatory Requirements for Junction Box Installation
Site electrical engineer shall plan and schedule activities for the installation of the instrument junction box in co-ordination with mechanical construction team.
Instrument junction boxes are subject to inspection and witnessing by the client.
Forms, procedures and sign off sheets for activity shall be prepared and submitted for review and approval of the client prior to beginning of any activity.
Ensure the availability of equipment’s like welding machines, to be able to weld to the steel post column, and drill machine to make a hole to mount JB boxes on its location where it is supposed to be placed.
The assigned supervisor or foreman shall make sure proper handling to avoid scratches or denting etc.
Ensure that the area is barricaded for safety purposes.
Make sure that electrical junction box supports are in accordance to standards and details of IFC drawings.
Necessary clearances shall be taken from other disciplines, (like piping and structural departments) before proceeding with the works to avoid any overlapping/interference of work executions.
The safety work permit shall be prepared based on the schedule of field erection activities, or in a daily base activities.
Junction box systems shall be electrically continuous, or safely grounded to earth as shown on the approved drawing.
Work shall be done according to the approved IFC.
Technical query shall be submitted officially for any amendment from the approved IFC drawing, prior to start any work.
All RFI’s shall be submitted 24 hours ahead of scheduled date of inspection.
All relevant attachments including IFC drawing must be attached on all submitted RFI’s.
Work execution, material approval and testing shall be monitored witnessed and recorded on documents in accordance to the inspection checklist.
Electrical inspector shall carefully check against IFC drawing for the following items:
a.) Correct elevation as per IFC drawing.
b.) Check the correct size and materials.
c.) Proper grounding as per IFC drawing.
d.) Area Classification.
e.) Check for maintenance accessibility.
Installation of Instrumentation Electrical Junction Box
JB installations shall meet the requirements of approved installation details and manufacturer’s recommendations.
All material of JB components and accessories shall be inspected and approved by consultant before installation.
Supports (Hot dipped galvanized, Unistrut channels, steel channels, steel angle bars, flat bars) shall be welded to structural steel columns and not limited to anchoring to concrete column, if necessary otherwise should be specified and approved.
Approved galvanized coating will be done for damaged galvanized surfaces.
Before touch-up coat, the metal surface must be cleaned, brushed to ensure effective coatings.
Junction boxes and instrument cases shall be positioned so doors may be fully opened, covers are fully removable, vent holes are not blocked, and adjustment screws, valves, wiring and piping connections are accessible.
The height installation shall be 5’6” (1675 mm) top of the junction box to grade level. Both on paved and unpaved area or directly mounted on beams. Or also 4’4” (1321 mm) centerline of the enclosure to grade level.
Electrical junction box system shall be connected to the overall grounding system as per approved IFC drawing.
All grounding cable jumper for JB must be as indicated in IFC Drawing.
Supports for electrical junction box must be fabricated and installed in a skillful manner considering proportionality and alignment.
All the supports installed shall be level and plumb.
Conduit or cable shall not enter through the top of field junction boxes. All conduits are to enter from the bottom of the junction boxes unless there are more conduits required that can fit.
All conduits coming from locations above the junction box shall have a low point drain adjacent to the junction box.
Adequate spare conduit or cable entry hubs fitted with threaded plugs shall be provided in the junction boxes.
Junction boxes shall be independently mounted and shall not rely on the mechanical support of the attached conduit for support.
All fastening hardware like bolt, nut etc. should be stainless steel.
Final alignment shall be done after installing the JB.
Ensure all elevation shall be as per approved IFC drawing.
Finally tighten the junction box bolts after alignment.