Notifying the DNO of a new connection

A new heat pump connection must be notified to the Distribution Network Operator (DNO).  Responsibility for this rests with the customer but the MCS scheme requires installers to facilitate this process.  

The process is simple and you can obtain a form from the DNO.  The reason this is important is that harmonics and flicker characterisitics of some service equipment can interfere with network performance.  In addition, each home has a maximum cut-out rating and exceeding this can present a safety issue.

The key things to remember are:

  • The installer is bound by the requirements of the Wiring Regulations which has guidance for connections
  • The installer needs to assess the adequacy of the DNO service equipment - guidance for this is availablke from the National Association of Professional Inspectors and Testers (NAPIT)
  • The installer needs to ensure that the heat pump will not mean the maximum cut-out rating of the dwelling is exceeded (on average this is around 100A for all electrical services and appliances but this is not formal advice and some properties may be as low as 30A)
  • In all cases the customer must apply to connect to the network before committing to installation and connection 
  • If the heat pump is <16A and complies with IEC61000-3-2 & IEC61000-3-3 the customer may connect and notify (i.e. assume DNO approval)
  • If the heat pump does not comply with IEC61000-3-2 & IEC61000-3-3 then the customer must apply to connect (i.e. wait for DNO approval)
  • If the heat pump is <32A and the heat pump manufacturer declares the heat pump meets the technical requirements of IEC61000-3-3 & meets the Class A limits of IEC61000-3-2 the customer may connect and notify (i.e. assume DNO approval)
  • If the heat pump is <32A and the heat pump manufacturer does not declare that the heat pump meets the technical requirements of IEC61000-3-3 or meets the Class A limits of IEC61000-3-2 the customer must apply to connect (i.e. wait for DNO approval)

The above bullet points are guidance only and it is the responsibility of the customer, facilitated by the installer, to check at all times with the DNO.