I've seen this dotted about and the frequency and legislation isnt clear. Well at least to me. Annual unless the environment is non standard then lower frequency?

Is RCD testing legislation or good practice? Is this test in between fixed wire testing much like annual thermal image testing?

Thanks

There is no legislation that requires 3-5 yearly inspection & test (I&T) of electrical installations.

There is guidance, from the Institution of Engineering and Techology (IET), for the time between the completion of a new installation and the first, inspection and test, however, from that point onward it is down to the competent person completing the inspection and test how long to the next test.  With the caveat the the insurance company of the undertaking may require I&T at a certain time period.

The same goes for Residual Current Device (RCD) testing and thermal imaging, there is no annual requirement.

Now there are two kinds of RCD testing, that undertaken with an RCD test instrument which would be completed during initial verification (IV), I&T & fgault finding, whereby the disconnection time of the device under prescribed fault currents is assessed, and if required the disconnection current, and the operator test.

The operator test is designed to be undertaken by non-electrically skilled persons, this needs to be undertaken as guided by the IET, or the device manufacturer instructions.

The IET guidance is every 6 months, (it has changed with the 18th Ed.), manufacturers guidance may be from monthly to annually, the device instructions or manufacturer need to be consulted to get this duration.

The older the RCD is the more important the testing is, older designs are obviously now, aged and the designs of older devices are more susceptable to siezure of the mechanical systems within the device.

The use of RCD's should be minimised as much as possible because they are the most unreliable menas of protection of a circuit that is used in electrical installations.

The 5 or 3 year thing either comes from the insurance company, or a misinterpretation by the electrician undertaking the assessment, they have taken the IET guidance as related to ongoing inspection & test, rather than the initial period to first inspection of a new install.

I have given an installation a single day before now because it was that bad, and client would do nothing about it if I dated the report in accordance with guidance, which I disagree with, and have made my voice known.

The guidance says that you can and should date the next inspeciton as per your feelings on the required time to next inspeciton once all the necessary remdial works have been completed.

However, the lack of understanding of the documents between those who prepare them, and those that receive them would result in the receiver seeing a date perhaps taking your example of 5 years, even though the report were unsatisfactory, with the result that likely the report would be filed, as satisfactory as it carries a date that says it needs to be done again in 5 years, even though it is actually unsatisfactory, and the 5 year date relates to the installation, after any remedial works are undertaken to make the installation satisfactory.

So ut is likely that the installation would be left in an unsatisfactory, possibly lethal state depending on what is found, if the 5 year date is used.  Hence why I would always date a report based on how urgently I felt the requirements needed to be remedied, based on my own experience of the installation, a C1 with exposed accessible live parts in an area accessible to the public, possibly say with children able to access them, would warrant immediate intervention, but, remembering that I would need permission from the client to do any work over and above the I&T, if permission were not given, would result in a danger notification, as good a temporary repair as I could do within the constraints of the allowable, and an inspection report dated the next day.

A C2 which was in a competent person only access area I might for example give a date 3, 6 or even 12 months down the road for.

This all depended on the installation, the hazard, and the client.

I would always try to explain to the client contact what the issues were and are, and their reaction would have an input into my risk assessment for the date of next inspection.

The RCD test you describe is that from the 17th Ed of the wiring regulations which requires a test instrument, and a competent person to undertake, as it requires the load removing from the outgoing side of the RCD, thus, an electrically competent person to isolate, open up the enclosure, disconnect the load form the RCD, undertake the test, then re-connect the load.  This is the classroom/textbook method.  Experienced & competent persons can prove the function of an RCD satisfactorily with one of these instruments without physical disconnection.  It is only if they have dubious test results would the load require disconnection.  Plus the non textbook method tests the RCD as it would be required to operate in the real world.

Within the electrical industry and it's asspciated documentation there is no such term as a fixed wire test (FWT), it seems to come from clients or insurance companies, I know not which.  The correct terms are a periodic inspection & test, which results in the provision of en Electrical Installation Condition Report (EICR).

Fuses are by far the most reliable  method of circuit protection because the physics of their operation is such that they cannot fail.  The issue with fuses is that they need to be used correctly and circuits need to be designed & constructed correctly to ensure that they disconnect correctly, clients do not want to pay for this, and many "electricians" cannot design circuits.  Also fuses are open to abuse, incorrect values fitted, bypassed with nails, screws or the like etc. spares need to be carried, they can be awkward to change, where as a circuit breaker is just switched back on, as long as the fault is gone.

The issue with fuses is that they rely on a path to earth to operate (or an overcurrent fault path), they do not detect earth leakage.  The reason RCD's are so unreliable is that they are not maintained in accordance with manufacturers instructions, they are mandated by companies, who are then not willing to maintain them to be safe.  If the OEM says that they must be tripped every day, week, month, 3 mohnths, 6 months etc. then they mean it, so RCD's are also open to abuse by the clients who do not maintain them, but, then complain when they fail under full test, or fail to operate when needed.  The required maintenance test is merely to press the test button, which is designed to be undertaken by unskilled personnel.