We have been working as a consultant for the past 17+ years and have experienced/observed that many engineers are not willing to provide the documents. To get accurate results it is important to understand the existing setup/system and give the proper inputs to the process.

Especially in Arc Flash Study, it is essential to get the exact PPE Category, Working distance, and Incident energy. And to get the accurate Incident energy proper fault clearance time based on short circuit study is Very Crucial. To get the proper result, input documents are required which are as follows –

1. Load List/Source List- Load Schedule/List is an estimate of the instantaneous electrical loads operating in a facility, in terms of active, reactive, and apparent power ( in kW, kVAr, and kVA respectively). The load schedule is usually categorized by switchboard or occasionally by sub-facility / area.

Load list helps in the Arc Flash Study process following way –

• Detailed classification of load concerning the panels, distribution network which gives an idea about the load in the system which helps in getting the accurate incident energy.
• Helps to select distribution voltage and distribution equipment sizing.
• Determine power requirements for the entire electrical system, permitting power sources both main and auxiliary systems to be sized.
• Provide bases for a cost estimate in case of the Greenfield Project

If the existing load list is not there one needs to get it prepared because without the proper load list we will not get the accurate incident energy which will fail the Arc Flash Study

2. Detailed SLD- The most important document in the process is the Single Line Diagram with All the relevant information. Reviewing the SLD is useful because it is typically packed with important information, such as bus voltages, protective device data, motors, load information, and cable characteristics to name a few, and is necessary to understand the system as a whole

Furthermore, the SLD will be used to efficiently plan the routes while in the field as well as conveniently record any note-worthy data next to a visual reference.

3. Cable Schedule- A cable Schedule is a document containing a list of Instrument cables. This document shows cable as well as gland required by each instrument or connection.

The information of the cable schedule consists of:

• Cable Number
• Cable Type / Specification
• Cable Size
• Cable Length
• Source and destination termination description
• Cable gland type and size for each incoming cable

This helps to

• Identify termination points from the plan to the actual job and connections to electrical equipment/panels.
• Identify specific cable during diagnosis and/or testing.

Cable sizing will help determine the voltage and current drop in the cable, without that load flow analysis is impossible.

4. Existing protection device data/setting- Protective devices in a power system are coordinated in time and a current pickup to provide for an orderly shutdown in case of a fault and to prevent blackouts. Changes in protective device settings solely to reduce arc flash hazards will inevitably result in a loss of coordination, resulting in misoperation during faults and unnecessary blackouts. Protective devices in a power system are coordinated in time and a current pickup to provide for an orderly shutdown in case of a fault and to prevent blackouts. Changes in protective device settings solely to reduce arc flash hazards will inevitably result in a loss of coordination, resulting in misoperation during faults and unnecessary blackouts. Protective devices in a power system are coordinated in time and a current pickup to provide for an orderly shutdown in case of a fault and to prevent blackouts. Changes in protective device settings solely to reduce arc flash hazards will inevitably result in a loss of coordination, resulting in misoperation during faults and unnecessary blackouts.

The protective device in a power system is coordinated in time and current pickup to provide for an orderly shutdown in case of a fault and to prevent backouts. Changes in protective device setting solely to reduce arc flash hazards will inevitably result in a loss of coordination, resulting in misoperation during faults and unnecessary blackouts.

Helps to :

• Identify if the design is capable of providing the system protection and is properly coordinated with other equipment.
• Select distribution voltage and distribution equipment sizing.
• Determine power requirement for the entire electrical system, permitting power sources both main and auxiliary system are to be sized.

5. Existing electrical panel dimensions

The electrical panel is an electrical distribution system that divides an electrical power feed into branch circuits, while providing a protective circuit breaker or fuse for each circuit, in a common enclosure. Panel circuits protect branch circuits from overloads and short circuits with the help of protective device coordination.

Hence to get the proper coordination to avoid arc flashes and to decide the arc flash boundaries knowing the electrical panel is crucial

• This information gives an idea about how many loads are connected to the panel and
• If the panel is capable of carrying the load.

Without knowing the dimensions one can’t properly conduct the Arc Flash Study.

All the above-mentioned input documents are required and important to conduct the arc flash study. For its effectiveness to get the exact amount of incident energy is required which can be determined by studying the input documents.