Electrical: Periodic Inspection and Testing

All electrical installations deteriorate with age and use. They should therefore be inspected and tested at regular intervals to check whether they are in line with International Standards, to ensure safe/satisfactory working condition for continued use and compliance with regulations. Such safety checks are commonly referred to as “periodic inspection and testing”.

A periodic inspection will:

• Reveal if any of your electrical circuits or equipment is overloaded.
• Find any potential electrical shock risks and fire hazards in your electrical installation.
• Identify any defective DIY electrical work.
• Highlight any lack of earthing or bonding.

  

How often is a periodic inspection required? 

The interval depends on the type of building or installation. It should be inspected and tested every: 

• 10 years for an owner-occupied home.  

• 5 years for a rented home. 

• 3 years for a caravan.

• 1 year for a swimming pool.

 

Other times when a periodic inspection should be carried out are:

• When a property is being prepared for renting or leasing.

• Before selling a property or buying a previously-occupied property.

Assessment of general characteristics 

  

The inspection takes into account all the relevant circumstances and checks on: 

• The adequacy of earthing and bonding.

• The suitability of the consumer unit and circuit breaker.
• The serviceability of switches, sockets and lighting fittings.
• The type of wiring system and the integrity of cables.
• Sockets that may be used to supply portable electrical equipment for use outdoors, making sure they are protected by a suitable residual current device (RCD).
• The presence of adequate identification and notices.
• The extent of any wear and tear, damage or other deterioration.
• Any changes in the use of the premises that have led to, or may lead to, unsafe conditions. 

Visual Inspection 

Unlike an initial verification, the periodic inspection should not be intrusive. Before starting the process, the extent and limitation of the inspection must be agreed with the person ordering the work. A minimum of 10% of the installation should be inspected, but if faults are found than this could increase. This is up to the judgment and experience of the inspector.

 

During visual inspection we would look at the installation with regard to:

 

• Safety 

• Age 

• Deterioration 

• Corrosion 

• Overload 

• Wear and tear 

• Non-compliance with regulations 

Periodic Testing

 

In a case where the original Electrical Installation Certificate or the latest Electrical Installation Condition Report is available, the level of testing is usually far less for periodic inspection and testing then for initial verification testing.

 

In most cases however, past documents are either missing or incomplete. If this is the case than 100% of the installation must be tested with the full sequencing.

 

There is no set sequence for the testing which may be required to complete the Electrical Installation Condition Report. This is up to the judgement of the person carrying out the periodic inspection and testing process as the circuit is already energised. However, we would advise the same sequence of tests as in the initial verification.

The sequence of tests:    

• Continuity of protective conductors, including main and supplementary bonding
• Continuity of ring final circuit conductors (If applicable)
• Insulation resistance
• Polarity test
• Earth electrode resistance test (If required)
• Earth fault loop impedance tests
• Prospective fault current test
• RCD test
• Phase sequence test (If applicable)
• Functional testing 
• Voltage drop test