Building Construction, Renovation, Maintenance & Advice

MEP (Mechanical, Electrical and Plumbing) Design

Electrical and Plumbing Systems

It is very important that the electrical and plumbing systems in our homes are designed and installed correctly to make sure they are effective and safe. Such systems become more complex and sophisticated as technical developments and home service advance and so the demands on te designers and installers of such systems also increase. Poor electrical systems can be dangerous and even cause death. Plumbing systems can also lead to infections and poor health. Here we look at the design of our household MEP systems and what you need to look for.


See the full Fixed Abode article here "The Confusion Of The Bipolar Bear"


What is MEP design?

Firstly what is MEP?

MEP stands for Mechanical, Electrical and Plumbing and refers to the technical systems that exist in our homes to make our lives reasonably comfortable.

Most people these days have piped water to our houses, we have a comfortable flushing water closet and often a septic tank to deal with that and we have electrical equipment and light bulbs.

In our homes we have ever more complicated technical systems which are increasingly "essential" to our cosseted lives. Why is it then that so many people trust the provision and maintenance of such systems in the hands of people who do not have the technical knowledge and skills to carry out this work

The three most important aspects of building design.

Let us get things into perspective. In any houses there are three aspects of the building that must have technically competent design and installation if the house is to be safe and function correctly. These are:

  1. The structure
  2. The electrical systems and
  3. The plumbing.

Bad plumbing we can suffer with but get the structure or electrical systems wrong and our lives are in danger (ever noticed how many fires there are due to bad wiring?).

Poor MEP design is a major problem

Throughout the world there are many buildings struggling with poor or inadequate MEP design.

The endless stream of requests to sort out problems with all aspects of water supply, sewerage and electrical systems can be put down to the basic fact that for most people their MEP systems were neither designed nor installed correctly. All across the world people are struggling and they call workers who carry out botch repairs on botched systems and very often the "repairs" only make things worse.

I went into a fairly new hospital in Indonesia recently and as I entered I was assailed by the stench of raw sewage.

Sewerage smells in brand new multimillion dollar buildings are a regular occurrence in developing countries. The cause is always the same - poor MEP design.

There is a shortage of good MEP design engineers

The fact is that good MEP designers are few and far between in spite of their importance in the building industry. I was recently asked to organise the redesign of MEP systems for two dozen new hospital buildings when it was found there were problems. Checking revealed the Engineer employed for the task had no formal qualifications or training in the work - he was cutting and pasting his drawings from existing poorly designed systems.

Modern buildings must have proper design of the electrical and plumbing systems

If you are having a house built you should ask, nay demand, that the architect shows you the MEP drawings. These should be completed BEFORE construction starts - why? I hear you ponder. The reason is simple, the MEP systems need to be built into the house not just added on later as an afterthought. How often do we see air conditioners stuck on the outside of a building like warts on a nose. Air conditioners and water heaters are part of everyday life these days and suitable places to hide them with ways to access and maintain them need to be designed into the building at an early stage as part of the architectural design.

From an MEP design point of view it is also very important that systems are designed at an early stage. Black water (sewerage), grey water (showers, washbasins and laundry waste water) and rainwater drains all need to be planned as to how they will pass through the building and out under floors. These pipes will need to be installed at an early stage during construction and MUST NOT compromise the structural strength of the building. You wouldn't believe how often in Indonesia drain pipes are put down the centre of structural concrete columns or through important beams.

What do MEP drawings include?

If your house has been properly designed there will be a series of drawings:

1. For the electrical systems there will be a master design drawing, much in the form of a chart, that lists all the circuits, the size of circuit breakers and the design of the main distribution panel. This drawing will list what will be connected to each circuit including lights, plug sockets, water heaters, air conditioners, fans, cookers, pubic curling tongs, etc. The drawing provides a calculation of the loads on each circuit and, of course, the earth connection.

2. Next there will be a drawing showing the wiring and placement of power circuits in the building with plug sockets and dedicated circuits for pumps, fans, air conditioners, water heaters, etc all indicated.

3. Next there will be a lighting plan showing the positions and wiring for the lights, switches and wiring.

4. Specialist installations such as swimming pools and garden lighting will have their own separate drawings.

There are numerous legally binding rules regarding the design of electrical circuits, all devised to protect our precious lives and the electrical drawings must reflect these rules.

Then there will be drawings for the plumbing systems including:

5. Clean water, bot hot and cold, supply systems.

6. A drawing for black water systems (sewerage).

7. A drawing for grey water systems (washing water).

8. A drawing for the design of the septic tank (if you have one) and one for any soak pit(s).

For even a basic house there should be at least 6 drawings for the MEP systems. You are well advised not to let construction start until you have seen these drawings. If you ask to see them and somehow they are not immediately available you need to be wary it could well be that there aren't any.

Some people may tell you that you don't need drawings but letting a vender of small nodding dogs recruited at the traffic lights loose with half a mile of cheap cable, a screwdriver in his hands and no plan is like a granny suffering from dementia knitting a Fair Isle jumper with no pattern (you don't know what a Fair Isle jumper is? believe me - you need a pattern).

MEP drawings make maintenence much easier

MEP drawings are not only essential during the construction process to make sure that construction is carried out properly and that systems will work correctly, they are also very important for ongoing maintenance, it is very difficult unblocking a sewer when you have no idea where the pipes are.

To design your systems you are well advised to use an MEP engineer.

Copyright © Phil Wilson 2009
This article or any part of it cannot be copied or reproduced without permission from the copyright owner.

5 September 2017 Copyright © Mr Fixit,
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