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  • Writer's pictureDean Pattison

Property Investment Tips.....Electric installations and buildings of multiple occupancy.

Updated: Feb 7, 2022

Electric and Buildings of Multiple Occupancy

We have seen an upturn in buildings such as pubs, clubs and office buildings become vacant, be sold to investors and then converted into living space.

These conversions often result in new flats or apartments which can impact on the way that energy supplies are configured.

If we use a pub as an example, it is a fair assumption that the existing electric supply will be three phase. By definition, there are three phases which means that as a best case scenario three meters could be installed. This can be problematic because of the position of the cut out which must be accessible to all tenants and cannot be situated inside one of the new flats.

If however a pub was being converted into more than three flats the investor will encounter a different proposition. When a building becomes one of multiple occupancy, it can generally only have a single supply entering the building. In this case a multi-service distribution unit (MSDB), commonly known as a bemco unit will be installed.

This involves a large diameter cable being pulled into a plant room or an external kiosk with a correctly sized MSDB fixed to the wall to provide a dedicated way to each flat. This configuration enables each flat to have its own electric meter so that each tenant has their own electric bill rather than the landlord managing the billing process.

What are the investors responsibilities?

  • A 125mm black rigiduct bend must be installed into the plant room or kiosk to enable the cable to be pulled to the termination point.

  • A fireproof backboard such as a treated sheet of ply must be installed to mount the MSDB unit.

  • When an MSDB is installed into a communal position, the adjacent space must be adequate. There are engineering recommendations requesting a space of 400mm x 400mm per meter installation as smart meters are much larger than the old style dumb meter and some of the energy suppliers install their own double pole isolator.

  • When a meter is positioned 3m away from a consumer unit (or more), the investor is required to ensure that there is a switched fuse isolator on each service to provide a safe point of isolation. Tails must also be installed into the isolator for the meter installer to connect to.

  • When the investor appoints an energy supplier it is essential to inform them that the installation engineer needs to be MSDB or three-phase trained as they will need to terminate the meters into the MSDB.

  • The investor needs to ask the energy supplier how much space they require for each meter installation.

  • The investor needs to clarify, with the energy supplier, who is responsible for installing the tails between the meter and the bemco unit.

Why are these questions important?

In our recent experience, if you don’t ask for a three-phase, MSDB trained engineer, the schedulers will send an engineer who is nor permitted to work on the equipment. There appears to be a greater number of single phase engineers than there are three phase trained engineers.

If there isn’t enough space for the installers equipment, they will abort the visit and you will have to wait until they become available for a second visit.

We have recently worked with the following companies:


Whilst they have a limited number of three-phase trained engineers, they can install to MSDB units. They will however require the cables to be installed between the meter position and the MSDB unit prior to their attendance. On our previous projects they have not installed their own isolator.

Scottish Power

There is also a requirement to install the tails between the meter position and the MSDB unit however in this case they will also install their own double pole isolator.

British Gas

BG install the tails between the meter position and the MSDB unit as well as installing a double pole isolator.

As you can see there are very subtle differences between each suppliers process but understanding this can be the difference between having meters installed on the first visit or having to make changes and book in a second visit.

Is there another option?

Yes, it is possible to ask for meters to be mounted in external meter boxes.

As long as the bottom of the meter boxes are a minimum of 750mm from the finished surface level and there is adequate space to have them side by side, this will be permitted.

Our advice to an investor would be to look at your requirements early. Speak with your architect to discuss the size of the plant room or kiosk and make sure that you have a suitable metring position at an early stage.

Also ensure that you have determined the correct number of supplies needed. For example, if you have ten flats and a ten-way MSDB is installed, you do not have room for the all important landlords supply.

Timing is important to you so please remember that no two jobs are the same!

Contact Utility Source on 01709 931297 for further information.

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