Lift motor room layout drawing

I have attached a layout drawing for a lift motor room here. It is for the same building as the nurses’ hostel building in the previous post that I sent on electrical riser rooms.

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RELATED ARTICLES: Substation room ventilation  | Electrical riser rooms | Electrical rooms design | Free electrical installation pictures (anchor post) |

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Part Drawing 1 – The lift motor room layout drawing

A building’s lift motor room is mechanical plant.

However, it is also a very important part of an electrical design engineer’s scope of work during the design and planning of a building project.

In many construction projects, this is one of the areas of the building space where the architects, structural engineers, mechanical engineers and electrical engineers battle each other for simplicity and easy design of their own scope the design work.

In a complicated building design for a building owned by private clients, the client herself might enter that battle zone just to make sure that the final design would be one with lowest cost of construction and takes up a minimum space possible.

Not that there is much space that can be rented out at a lift motor room level, but the attitudes seemed to encompass almost everything.

Part Drawing 2 – Riser rooms and lift shaft layout drawing

I just attach this drawing again here for the benefit of beginners. It was already included in the earlier post on riser rooms.

Compare the two diagrams together and observe the riser rooms for electrical (ELEC), master antenna TV system (MATV) and telephone (TEL) in Diagram 2.

This is an eight-storey building with the lift motor room at the ninth floor (the roof level).

So all the electrical riser shafts stop at seventh floor including the cold water shaft.

I am not going to say much on the lift motor room today. I just wanted to share with you this drawing.

In any case, beginners only need to study the layout and try to see the logic of why something is located where it is. There are enough labels on the drawing to indicate what that something is.

If the description is not enough, try to make a guess.

For example, “DB ELMR”. DB stands for distribution board. That is a standard notation for electrical distribution board. The symbol there is also quite standard.

ELMR? You guessed it. LMR stands for Lift Motor Room. While the “E” has been added to indicate that this distribution board has been supplied (electrical supply) from the Essential supply of the building.

Essential supply is the power that has been backed by the standby electricity generator of the building.

I will upload the single line drawing for the lift switchboard (not the lift control panel) and the DB ELMR soon. With that you will be able to see the overall picture of the distribution system here.

I could have uploaded the drawing in this post, but that could confuse the search engines about the main keywords for this post.

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Electrical riser rooms

This post talks about electrical riser rooms, or electrical service ducts, as they are sometimes called. These rooms are usually not so obvious. They don’t look prominent, not like the standby generator rooms or the high voltage rooms.

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RELATED ARTICLES: Substation room ventilation  | Electrical rooms design | Lift motor room layout drawing | Free electrical installation pictures (anchor post) |

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Picture 1 – A partial view of an electrical riser room at a high rise office building

Picture 2 – Another view inside the same riser room (on the left of the bus duct risers)

They are still needed, however, for a proper and efficient operation of an electrical installation in buildings especially those of the multi storey and high rise types.

They are used to house the vertical submain cables that carry electricity supplies to the upper floors of the buildings and to the plants and machines at the roof top such as the chiller plants, cooling towers or the lift motor rooms.

The vertical rising mains that supply the lateral distributions on individual floors are also installed in these vertical ducts.

Often these concrete vertical ducts are as large as a small room. That is why it is often called electrical riser rooms.

The electrical riser rooms do not have to be stacked vertically like the toilet risers or wet stacks.

However, it is better to do so as it would minimize turns and sharp bends that can damage the cables.

Riser rooms stacked straight up from the lowest floor to the highest building floor would also minimize the length of the electrical cables required.

Minimum cable length not only reduces the cost directly. Longer route of an electrical cable run may cause too much voltage drop along its length that may require it to be changed to one or two size larger.

Larger cables cost more money.

Diagram 3 – A ground floor layout of building services

Diagram 4 – A zoomed in view of the electrical riser rooms’ layout

The above two diagrams shows an example of electrical risers in an actual design. Diagram 4 is actually a zoomed in view of the electrical riser area to give you a clearer view.

This layout is for a nurses' hostel building at a large hospital. There were a whole range of residential buildings there so I picked this one as an example.

I will just explain a little bit here to help beginners get started.

ELEC – electrical riser room.

MATV - the riser room for the MATV (master antenna television) system. If the building has a CCTV (closed circuit television) system, the riser cables will run inside this riser shaft to connect to upper floors of the building.

In many building design, a single riser shaft is used to run all the ELV (extra low voltage) services to the upper floors.

(Note: When all the riser rooms at each floor are stacked up vertically straight up, then it forms a shaft. So it is called a riser shaft.

Put in another way, a long time ago when the ancient builders found out how to build a building with multiple floors one on top of the other, the riser started as shaft or a vertical wooden duct.

In order to make it safe for working inside it at each floor, they extended the floor into part of the riser. Then it became like a room. So it was called a riser room.)

TEL – for telephone cables and equipment.

DR – dry riser. A building exceeding a certain height is required to install vertical pipes with inlets at the ground level. These pipes will be used to pump water from fire engines to the upper floors so the firefighters can fight fire.

If the building height is even higher, dry pipe riser would not be accepted by the fire department. A wet riser system would then be required. This is the same piping as the dry riser but with water tanks to store water and sufficient number and horsepower of pumps to always keep the water under sufficient pressure in case there is a fire in the building.

WATER – Water is not available here. Just pipes that carries domestic water. Designers just label it WATER as a short form for COLD WATER.

ON CALL – You would only have this at residential buildings for hospital employees. They have a communication system that can call the employees on standby when they have to report for duty immediately.

The red rectangular symbol inside the electrical riser is the electrical panel. You will find one or more electrical panels at the upper floors also.

(Note: The ELEC, MATV and TEL riser rooms are all part of the electrical risers. All these systems are part of the electrical services in a building system.

Many building are equipped with building automation systems or sometimes called building control systems. Many engineering firms classify this system as a mechanical system and therefore it is designed by the mechanical engineers of the firm.

Some consultant companies, however, consider that it part of electrical systems. So we the electrical engineers need to take care of all the designs.

Likewise for vertical transportation systems such as lifts and inter-floor escalators. However, a much smaller number of engineering consultants put this under the scope of electrical engineers. A few still practice that and I happen to be working for one of those firms many years ago.)

Individual floor electrical rooms

Each individual floors of a significant size usually needs at least one dedicated electrical room to house the electrical distribution equipment for that floor.

Sometimes the vertical service ducts may be able to fulfill this function in which case a separate electrical room may not be necessary.

The architect may then need to make these service ducts bigger to give them enough space for proper operation and maintenance.

The electrical rooms at each floor house the electrical panels that serve the final circuit wiring.

Therefore, they should be as close as possible to the load center of the area that it serves.

I will upload some detail layouts of the electrical riser rooms in future posts for readers who need them.

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Electrical rooms design

During the design of electrical installation for buildings, the spaces required as electrical rooms need to be provided for very early in the planning and design stage. Failure to do so would cause difficulties when the designers start producing their detail designs.

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RELATED ARTICLES: Substation room ventilation  | Electrical riser rooms | Lift motor room layout drawing | Free electrical installation pictures (anchor post) |

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Types of buildings electrical supply needs

Two (or sometimes three) sources of electricity are normally required in high-rise buildings:

1) The normal mains supply from the electric supply authority or the local electricity supply company in some countries.

2) The standby or emergency supply for the standby electric generators. In most situations this supply is not an option, but a mandatory requirement for buildings that exceed a certain size.

3) The uninterruptible power supply, or commonly called UPS. This is only needed in certain types of office buildings and in some hospital buildings.

The choice of the supply voltage levels from the supply authority

The normal mains supply taken from the authority may be taken at HV (high voltage, normally 11 kV in this country), or LV (low voltage, 415 Volt, three-phase four-wire).

Whether it is LV or HV depends on the size of the maximum electrical demand to be expected of the planned building when it is in full operation.

It also depends on the effects of voltage drops and the level of voltages that are currently available from the supply authority.

Supply authority’s HV switch-room

When the incoming supply is HV, the authority usually only require a HV switch room to be built and handed over to them. This is where they house their high voltage switchgears and other equipment.

The location of this room must allow for easy access by the authority’s maintenance people and it should not present inconvenience to the occupants of the buildings or disrupts the building’s normal functions and operations.

Electrical distribution cables from the authority’s distribution network in the area will tapped and looped to the HV switchgear panels in this room. A series of panels are usually installed by them here.

Then from one of the HV panels, a supply feeder cable will be laid and connected to the consumer HV room and the HV energy meter.

Supply authority’s 11kV/.41vV transformer room

Often during the negotiations for the application of the supply, the authority may require that a transformer room is also provided and handed over to them together with the HV room.

Usually this happens when there is no suitable site available for their substation in the vicinity. This usually happens when the planned building site is at a congested area of towns like the city center.

Consumer HV room

As mentioned, the HV feeder cables that will carry the electric current to the planned building will need to connect to the consumer’s HV switchboard in the consumer HV room.

Part of the cost born by the authority in order to give supply to the new building are usually charged to the consumer (in what is usually called a “contribution fee”) and need to be paid before the authority commence their installation work.

Therefore, the nearer the consumer HV room is to the authority HV room, the shorter the HV cables that need to be laid and the lower the cost of the cables that need to be shared by both parties.

So in many cases, the consumer HV room needs to be nearer to the authority’s HV room.

Transformer room

Other than the HV room, the consumer also needs a transformer room, the LV room and the standby generator room.

When a large UPS supply is used, then a UPS room may also be needed.

The consumer transformer room and the LV room need to be as close to each other as possible in order to minimize the voltage drop.

For every meter of extra distance between these two rooms, a significant cost needs to be spent to overcome the voltage drop to an acceptable level.

Incoming supply at Low Voltage

If the supply taken from the authority is LV, then the supply authority will require a HV room and an transformer room to be provided.

The two rooms must be situated adjacent to each other although sometimes they accept that the HV switchgear and the transformers share the same room to save space.

The consumer is also required to provide a main switch room adjacent to the transformer room. The standby generator room also needs to be near the main switch room.

The locations of the electrical rooms

The location of the electrical rooms is also a major factor in the design of all types of electrical installations.

There are a few major requirements that must be taken into account when deciding on the locations for these rooms.

1) They should be located inside the buildings, as near as possible to the load centers.

2) The rooms should be as near as possible to each other.

3) They need to be accessible by maintenance vehicles and maintenance people for purposes of installation, operation and maintenance works.

4) They should be accessible by heavy vehicles during installation and when replacement of heavy equipment is necessary.

5) They should be adequately ventilated.

6) They should be adequately secured from possible disasters like flood, or even vandalism.

The above electrical rooms are in the category of substation rooms.

These rooms can actually be located at a separate building adjacent (or hidden behind) the main buildings.

However, there are still number more rooms that are needed by the electrical installation.

Other electrical rooms

1) Electrical service ducts or electrical risers. These service dusts are used to house the vertical submain cables that carry supplies to the upper floors of the buildings and to the plants and machines at the roof top such as the chiller plants, cooling towers or the lift motor rooms.

The vertical rising mains that supply the lateral distributions on individual floors are also located in these vertical ducts.

2) Individual floor electrical rooms. Each individual floors of significant size will usually need at least one dedicated electrical room to house the electrical distribution equipment for that floor.

However, sometimes the vertical service ducts may be able to fulfill these functions in which case a separate electrical room may not be necessary.

The architect may need to make these service ducts (sometimes also called “riser rooms”) bigger to give them enough space for proper operation.

The electrical rooms at each floor house the DB (distribution boards) that serves the final circuit wiring. Therefore, they should be as close as possible to the load center of the area that it serves.

Very tall buildings

If the planned building is very high (let’s say a 40 storey office building), or in cases where heavy loads are located at higher levels of the building, it may be necessary to provide substations at the higher levels of the building.

For the 40-storey office building, an 11/.415 kV substation may be necessary at one of the upper floor. It may be located at twentieth floor, for example.

All the substation room spaces as explained earlier will then need to be provided.

The floors of this substation will need to be designed by the structural to handle the loads of all the substation equipment.

Coordination with other design consultants and engineers

The above requirements need to be planned for at the early stages of the design and coordinated with the architects and structural engineers.

In many projects, the room spaces and their locations as requested by the electrical engineers are subject to “negotiations” with the architects and structural engineers, not merely technical coordination.


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