1.6: Condition Of Isolator (where present)

Condition Of Isolator (where present) - Electrical Inspection Training

Checking The Condition Of Isolator (where present)

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The last of the inspections of the external supply equipment, checking the condition of the isolator is quite straightforward.

This particular inspection, like the rest of the inspections within the 1.* range, is VISUAL ONLY. As beforehand, it is more an inspection to see if there has been any damage to the supply/service equipment.

Not every installation will have an isolator fitted here and thus this inspection only applies to situations where an isolator is already present.

Usually installed by the electricity supplier, in most domestic scenarios this is a double pole switch in the meter tails after the electricity meter itself.

If you aren’t quite sure what to look for when inspecting the isolator, or need to ensure that you are inspecting to the latest standards, our full & complete 18th edition electricians guide to the “condition of isolator” will help unravel everything for you!

How Do I Check The Condition Of Isolator?

In this inspection, it is really just a case of checking over the isolator and looking for any signs of wear and/or damage.

Whilst relatively simple in it’s operation (and thus the inspection should also be fairly easy), there are a couple of points that you should ensure you have looked over properly.

As the isolator is usually fitted alongside the rest of the supply equipment, this can be in an unforgiving environment (ie: damp cellar or external meter box).

Although relatively rare to find the isolator switch in a particularly bad condition, there are a number of points which are worth inspecting carefully to ensure the safety of the isolator

You should pay attention to inspecting the following points closely (VISUAL inspection only):

  • Physical Damage to the Isolator – Check the outer casing/enclosure. Are there any obvious signs of damage? Cracks, pieces missing or otherwise compromised should be fairly obvious to the inspector when checking it over.
  • Incorrect IP rating of Isolator Enclosure – It is important to ensure that the enclosure of the isolator is the correct IP rating and there is no “oversized” penetrations which open up access to live parts within.
  • Potential Thermal Damage to Isolator – We have come across examples of loose terminals within an isolator causing thermal damage to the switch assembly.
  • Does the Isolator Work? – It may seem obvious but you need to check that the isolator actually works. Disconnect the supply and check that the supply is broken to the consumer unit. Once you have done this, re-energise and then check that the power has been restored.
  • Is The Isolator Rating Correct? – You need to check the amperage rating of the isolator and ensure that it is sufficient to carry the current which will be drawn by the installation.

Checking Condition of Isolator

In the Pictures Below are a selection of pictures showing the inspections required when you are checking condition of isolator:

Condition Of Isolator (where present) - Electrical Inspection Training
In Line Isolator for Supply in Block Of Flats
checking condition of supply isolator distributors isolator
Checking Condition of Isolator within external supply meter cupboard

Summary & Conclusion

Ultimately checking condition of isolator is an inspection of common sense.

If the isolator is damaged or incorrectly installed then this must be recorded on the schedule of inspections.

The classification code to be given really depends on the severity of the issue seen. Any form of bare live connections or physical damage to the isolator that exposes live parts would be a C1 – DANGER PRESENT issue.

Isolators with thermal damage or other damage to the equipment (which does not expose bare live parts) would generally be coded C2 – POTENTIALLY DANGEROUS. We would also use the C2 code for instances where the rating of the isolator is not sufficient.

There may be a number of instances where a C3 – IMPROVEMENT RECOMMENDED code is warranted depending on how severe the issue is.

We intend to further develop this section and provide a full breakdown of all applicable EICR codes, similar in a way to the the popular codebreaker style books, however with pictures and further insight….


Please note that the DNO will not get involved with the isolator. Whilst many energy suppliers will actually fit the isolators themselves during works, it is difficult to get them to take ownership of the equipment when it comes to repairs.

As the isolator is generally fitted “after” the metering equipment, most energy suppliers seem to palm off the responsibility and say that this equipment belongs to the customer.

However If you do need to find the electricity supplier, the customer themselves should be able to give you these details. However, if you are dealing with an empty property, you can check on the following website to see who the supplier is.

2 Responses

  1. While carrying out EICR’s reports I have come across DP Main Isolators with only the Line conductor going through the DP Main Switch, the neutrals are joined in a Henley block. Just doesn’t sit right with me. This was obviously done by the supplier. Was just wondering what other peoples thoughts are on this?

    • Hello Ryan, thanks for posing the question and apologies for the delay replying.

      My thoughts would be that this does not meet the requirement for a linked main switch (537.1.4) ‘A main switch for operation by ordinary persons……shall interrupt both live conductors of a single- phase supply.’ I would be considering this a C2 – potentially dangerous fault.

      Hope that helps?
      Kind regards, Electrical-Assistance

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