Autocad Electrical drawing & HVAC

17/02/2024

17/06/2023

https://youtu.be/Box5UvN9iWQ
AutoCAD lighting Design for floor plan AutoCAD Electrical

17/06/2023

LIGHTING DESIGN BY LUMEN METHOD (WITH EXAMPLES):

IMPORTANT DEFINITIONS IN ELECTRICAL LIGHTING DESIGN:
The following are some of the definitions which we come across in the design of electric lighting scheme.
1) UTILIZATION FACTOR:
Utilization Factor or Co-efficient of utilization. It may be defined as “the ratio of total lumens received on the working plane to the total lumens emitted by the light source”.i.e.
Utilization factor =Lumens received on the working plane/Lumens emitted by the lamp
FACTOR EFFECTING UTILIZATION FACTOR:
Type of light, light fitting, Colour surface of walls and ceiling, mounting height of lamps, Area to be illuminated
Its value lies between 0.4 and 0.6 for direct fittings it varies from 0.1 to 0.35 for indirect fittings
2) Depreciation or Maintenance factor
It may be defined as “the ratio of illumination under normal working condition to the illumination when everything is clean or new” i.e.
D.F = Illumination under normal working conditions / Illumination when everything is clean.
The maintenance factor is based on how often the lights are cleaned and replaced. It takes into account such factors as decreased efficiency with age, accumulation of dust within the fitting itself and the depreciation of reflectance as walls and ceilings age. For convenience, it is usually given as three options:
Good = 0.70
Medium = 0.65
Poor = 0.55
3) WASTE LIGHT FACTOR:
When a surface is illuminated by a number of lamps, there is certain amount of wastage due to overlapping of light waves. Its value will be between 1.2 to 1.5
4) REFLECTION FACTOR:
It may be defined as “the ratio of luminous flux leaving the surface to the luminous flux incident on it”. It’s value will be always less than 1
5) ABSORPTION FACTOR:
When the atmosphere is full of snow or smoke fumes, it absorbs some light. Hence absorption factor may be defined as “the ratio of net lumens available on the working plane after absorption to the total lumens emitted by the lamp”. It’s value varies from 0.5 to 1
6) LUMINOUS EFFICIENCY OR SPECIFIC OUT PUT
It may be defined as “the ratio of number of lumens emitted to the electric power in take of a source” it’s unit is lumen/watt (lm/W)
7) SPACING TO MOUNTING HEIGHT RATIO (SHR)
The Spacing to Mounting Height Ratio (SHR) is the spacing between luminaires divided by their height above the horizontal reference plane.
8) ROOM INDEX:
The room index is a ratio, describing how the room's height compares to its length and width. It is given by:


Where L is the length of the room, W is its width, and Hm is the mounting height above the work plane.
LUMEN METHOD STEPS:
1. Find required lux level
2. Select luminaire
3. Determine room index
4. Determine Number of Fixtures


N = number of lamps required.
E = illuminance level required (lux)
A = area at working plane height (m2)
F = average luminous flux from each lamp (lm)
UF= utilisation factor,
MF= maintenance factor,
5. Determine Minimum spacing between luminaire
Minimum spacing = SHR * Hm
Hm= Mounting height
SHR= Space to height ratio.
6. Determine Number of required rows of luminaire along width of the room
Number of required rows= width of the room/ Minimum spacing
7. Determine Number of luminaire in each row
Number of luminaire in each row= Total luminaire / Number of rows
8. Axial spacing along luminaire
Axial spacing= Length of the room/ Number of luminaire in each row
9. Transverse spacing between luminaire
Transverse spacing = Width of the room/ Number of luminaire in each row

13/06/2023

https://youtu.be/r4jHWca6b4U

What is the limit command?LIMIT command. The LIMIT command shows the address limits and size of the contiguous storage area being browsed and resets the curr...

11/06/2023

Conduit Layout using AutoCAD
Things to Know
1. Methods of Point Wiring
2. Methods of Circuit Wiring
3. Guideline for Switchboard Connection
4. Guideline for Socket Connection
5. Guideline for ECC
6. General Guideline
7. Symbols used in Conduit Layout
8. Conduit Size Calculation
9. Conduit Drawing Example
Methods of Point Wiring
Wiring between a Light/fan point and its corresponding switch board is termed as Point Wiring. Wiring for a Light/Fan point shall be made using one of the methods i.e, (i) Surface Wiring or (ii) Concealed Wiring. It is assumed that the load of such a point is not in excess of 100watts in general, in special this may be up to 200 watts. For wiring of a point one Red and one Black PVC insulated copper cable shall run between a point and its switch board. Cable joints inside conduits or within channels are forbidden. The current carrying capacity for such a circuit shall not be more than 5A for a domestic or a commercial building. The minimum size of a cable for such wiring shall be 1.5 mm2 . Common neutral shall not be used under any circumstances.


Methods of Circuit Wiring
Wiring between a switch board and a BDB/SDB/DB is called Circuit Wiring. Circuit wiring shall be done with a live cable, a neutral cable and an ECC cable for a single phase circuit. Sometime this circuit is also referred to as sub‐circuit. An ECC must be provided with each circuit. The ECC at the Switch Board end shall be terminated in the earth terminal of the metal part of the Switch Board using a brass screw/bolt and a nut. End of the ECC shall be terminated in the Earthing Bus bar of the BDB/SDB/DB. The ECC in this case shall be PVC insulated copper cable of appropriate size but with Yellow+Green bi‐color insulation. For each circuit, the live wire must be drawn using red color insulated PVC cable and the Neutral Wire shall be drawn using black color PVC insulated cable. Common neutral shall not be used under any circumstances. Each circuit must have it’s own neutral cable. Use of common neutral cable for more than one circuit is not permitted.

Guideline for Switchboard Connection
The feed cables for such a circuit must have fuse or miniature circuit breaker (MCB) at the originating point in the Distribution Board or Sub‐Distribution Board or Branch Distribution Board. Both the Red (L) and Black (N) cables of a final circuit shall run from a BDB/ SDB up to the Switch board without a joint. Similarly, both the Red (L) and Black (N) cables of a point shall run from the point up to the switch board. Cable joints are to be made in the switchboard back box. Circumstances might arise where this is not possible. Under those circumstances, joints shall be made using approved cable joint methods.
Guideline for Socket Connection
The feed cables for such a circuit must have fuse or miniature circuit breaker (MCB) at the originating point in the Distribution Board or Sub‐Distribution Board or Branch Distribution Board. For some high current applications, additional fuses/ circuit Breakers adjacent to the sockets are recommended. The phase wire (Red cable) shall be connected to the L terminal of the socket-outlet through the combined switch and the neutral wire (Black cable) shall be directly connected to the N terminal of the socket. Earth Continuity Conductor (ECC) for such a socket outlet shall be connected to the Earth terminal of the socket. Single phase socket-outlets receiving connection from two different phases located in the same room is to be avoided. However, if it is essential to have such socket connection these must be located 2m or more apart.
Guideline for ECC
ECCs of appropriate size must run from an MDB to it’s DBs, from a DB to its corresponding SDBs, from an SDB to the Switch Boards under this SDB, from an SDB to the BDBs if there are any, from a BDB to the Switch Boards under this BDB. The ECC at the Switch Board end shall be terminated in the earth terminal of the metal part of the Switch Board back box using a brass screw/ bolt and a nut. The BDB / SDB / DB end of the ECC shall be terminated in the Earthing Busbar of the BDB/SDB/DB. ECC runs from the MDB to the LT Panel Earthing Busbar of the Substation. At each point the ECC shall be terminated in a copper Earthing busbar. In metal switch board back boxes and in metal socket back boxes appropriate copper or brass bolt nut termination shall be provided. ECC of an earthing system joins or bonds together all the metal parts of an installation. PVC insulated copper cables of appropriate size having Green+Yellow bi‐color insulation shall be used as ECC. The minimum size of the ECC shall be 4.0mm2 as per BNBC.
General Guideline
At the beginning, the Light points, Fan points, Socket points, Switch Boards, BDBs, SDBs, FDBs. DBs and MDBs shall be located on each plan based on convention, suitability, application and safety view point. Conduit layout and cable layout shall then be shown on the drawing. Appropriate planning should be made in which there shall be adequate spare capacity in the conduits placed in roof slabs so that unforeseen situation during ex*****on of the installation can be taken care of. Conduits will run through the roof and then bend downward for going up to the outlets, DBs, Switch Boards, Sockets. Cables of an electrical distribution installation are drawn through Electrical Conduits. At present, two types of conduits are used (i) PVC Conduits and (ii) Metal Conduits. Of these, due to the availability of good quality PVC pipe and for the ease of installation, PVC Conduits are widely used. Its not necessary to draw conduits to each switchboard. In large design only one conduit may carry the wires for a group of switchboard
In designing the wiring layout, power (socket) and heating (socket) sub‐circuits shall be kept separate and distinct from light and fan sub‐circuits. All wiring shall be done on the distribution system with main and branch distribution boards placed at convenient positions considering both physical aspects and electrical load center. All types of wiring whether concealed or surface, shall be as near the ceiling as possible. In all types of wiring due consideration shall be given to neatness and good appearance. Design must be made in such a way that sufficient clearance (space) is left inside the concealed conduits (i) for the ease of pulling the cables and also (ii) for adding few more cables in case of necessity during future modification.

Pull Boxes:
Pull boxes must be placed closed to the ceiling where conduits from the ceiling are going downward toward a switch box or are going toward a socket box or are going toward a BDB/ SDB/ DB / FDB. Pull boxes are extremely essential for pulling the cables without injuring the cables and thus should not be avoided under any circumstances. These are also essential for future maintenance and extension work. Pull boxes must be placed in the ceiling of office or factory building where conduits are running over a long distance between two walls and where fixed walls are not available and also where heavy beams are used. In case of big cross-section beams, pull boxes shall be placed closed to the beams.

For Domestic and Office Buildings:
5A Light / Fan Circuits must be used for all Domestic and Residential buildings. 5A Light / Fan Circuits are also to be used for Office and commercial Buildings. The corresponding circuit wire in the BDB/ SDB/ DB then shall not be less than 1.5 mm2 .
For Office and Commercial Buildings having large open floor areas:
Under unavoidable circumstances in case of difficulties in forming 5A Light/Fan circuits for Office and Commercial Buildings having large open floor areas, 10A Light/Fan circuits may be used. The corresponding circuit wire in the BDB/ SDB/ DB then shall be not less than 2.5mm2 . However use of 5A Light / Fan Circuits is still emphasized.
For Industrial / Factory Buildings having large open floor areas:
For Industrial / Factory Buildings having large open floor areas, 10A Light / Fan circuits may be used.

For Industrial / Factory Buildings/ Warehouses having too large open floor areas:
For Industrial / Factory Buildings / Warehouses having large open floor areas, efforts should be given to use circuits not exceeding 10A. The corresponding circuit wire in the BDB/ SDB/ DB then shall be not less than 2.5 mm2 . For Industrial / Factory Buildings having very large open floor areas,15A Light / Fan circuits may be used as exceptional cases only. The corresponding circuit wire in the BDB/SDB/DB then shall not be less than 4 mm2 . Spring’22_LS07_EEE 448_Page 11 General Guideline Increase in the sizes of the aforementioned cables may be required if the distance is too long. Voltage drop calculation will give the guidance in that case.
Separate branch circuits from miniature circuit breaker (MCB)
Separate branch circuits shall be provided from miniature circuit breaker (MCB) of a DB/ SDB or fuse of the Fuse distribution boards (FDB) for Light/Fan. Separate branch circuits shall be provided from miniature circuit breaker (MCB) of a BDBD/ SDB or fuse of the Fuse distribution boards (FDB) for automatic and fixed appliances with a load of 500 watt or more and socket outlets. Each automatic or fixed appliance shall be served by a protected socket circuit.
Length of a lighting circuit:
The length of a lighting circuit shall be limited to a maximum of 30 m, unless the load on the circuit is so small that voltage drop between the over‐current protective device and any outlet is below 1%

08/06/2023

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08/06/2023

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