Refundable deposit (no VAT).  

This is the meter is only used where there is a substantial electricity supply to the sub-metered unit, usually only on industrial parks.  

You might have a Three Phase mains supply to your residential site, even if it is an HMO as small as four units, but almost certainly the mains supply will have been split into individual phases inside your building, and you will want our Single Phase sub-meters.  

You will know if you need three phase sub-meters, but naturally we are happy to advise: