17th edition domestic installation certificate

When the end of the finger is introduced into the enclosure, provided the lamp does not light then the protection is satisfactory Figure 6. Protection is afforded if the wire does not enter the enclosure. Appendix 13 of BS outlines the tests required. The requirements are: 1.

All fuses and single pole switches and protective devices are in the line conductor. The centre contact of an Edison screw type lampholder is connected to the line conductor except E14 and 27 types. All socket outlets and similar accessories are correctly wired.

As discussed earlier, polarity on ring final circuit conductors is achieved simply by conducting the ring circuit test. For radial socket outlet circuits, however, this is a little more difficult.

The continuity of the cpc will have already been proved by linking line and cpc and measuring between the same terminals at each socket. Whilst a line—cpc reversal would not have shown, a line— neutral reversal would, as there would have been no reading at the socket in question. This would have been remedied, and so only line—cpc reversals need to be checked.

This can be done by linking 39 CHH A line—cpc reversal will result in no reading at the socket in question. When the supply is connected, it is important to check that the incoming supply is correct. This is done using an approved voltage indicator at the intake position or close to it. Connection to earth is made by an elec- trode, usually of the rod type, and preferably installed as shown in Figure 8.

If we were to make such measurements at increasingly longer distances from the electrode, we would notice an increase in resistance up to about 2. There are two methods of making the measurement, one using a proprietary instrument and the other using a loop impedance tester.

The earth electrode resistance test is conducted in a similar fashion, with the earth replacing the resistance and a potential electrode replacing the slider Figure 8.

In Figure 8. The method of test is as follows: 1. Place the current electrode C2 away from the electrode under test, approximately 10 times its length i. Place the potential electrode mid way. Connect test instrument as shown. Record resistance value. Move the potential electrode approximately 3 m either side of the mid position, and record these two readings. Take an average of these three readings this is the earth electrode resistance. Determine the maximum deviation or difference of this average from the three readings.

Express this deviation as a percentage of the average reading. Multiply this percentage deviation by 1. Provided this value does not exceed a figure of 5 per cent then the accuracy of the measurement is considered acceptable. The value obtained is added to the cpc resistance of the protected circuits and this value is multiplied by the operating current of the RCD. The resulting value should not exceed 50 V.

If it does, then Method 1 should be used to check the actual value of the electrode resistance. So let us remind ourselves of the component parts of the earth fault loop path Figure 9. Starting at the point of fault: 1. The cpc. The earthing conductor and main earthing terminal. In the latter case the metallic return is the PEN conductor. The earthed neutral of the supply transformer. The transformer winding. The line conductor back to the point of fault. Overcurrent protective devices must, under earth fault conditions, disconnect fast enough to reduce the risk of electric shock.

This is achieved if the actual value of the earth fault loop impedance does not exceed the tabulated maximum values given in the relevant parts of the IEE Regulations. The purpose of the test, therefore, is to determine the actual value of the loop impedance Zs , for comparison with those maximum values, and it is conducted as follows: 1.

Ensure that all main equipotential bonding is in place. If a neutral is not available, e. Press to test and record the value indicated.

It must be understood that this instrument reading is not valid for direct comparison with the tabulated maximum values, as account must be taken of the ambient temperature at the time of test and the maximum conductor operating temperature, both of which will have an effect on conductor resistance.

This requires actually measuring the ambient temperature and applying factors in a formula. Clearly this method of correcting Zs is time consuming and unlikely to be commonly used. Hence, a rule of thumb method may be applied which simply requires that the measured value of Zs does not exceed 0.

Table 9. Do not replace with a higher rated breaker for test purposes, use the calculation method. External loop impedance Ze The Value of Ze is measured at the origin of the installation on the supply side with the means of earthing disconnected. Do not conduct this test if the installation cannot be isolated. The RCD testers used are designed to do just this, and the basic tests required are as follows Table Set the test instrument to the rating of the RCD.

Operate the instrument and the RCD should not trip. Operate the instrument and the RCD should trip out in the required time. Table There seems to be a popular misconception regarding the ratings and uses of RCDs in that they are the panacea for all electrical ills and the only useful rating is 30 mA!

Firstly, RCDs are not fail safe devices, they are electromechanical in operation and can malfunction. Secondly, general purpose RCDs are manufactured in ratings from 5 to mA and have many uses. The accepted lethal level of shock current is 50 mA and hence RCDs rated at 30 mA or less would be appropriate for use where shock is an increased risk.

At the origin this may be ascertained by enquiry or measurement, whereas at other points, measurement is the only option. Where the lowest rated protective device in the installation has a breaking capacity higher than the PFC at the origin, then measure- ment at other points is not needed. Both should be measured and the highest value recorded, although there is no harm in recording both.

The testers are designed for single phase use, so where a value of PSCC is required for a three phase system it may be determined by multiplying the single phase by 2, or more accurately 1. The direction of three phase motors can be reversed simply by reversing any two phases. In consequence the correct sequence is essential to ensure the right rotation. Paralleling of two three phase generators or of a generator to the three phase public supply system requires their phase sequences to be synchronized.

The instrument is simply a small three phase motor with a dial that indicates in which direction the supply is rotating Figure Operating this test facility creates an artificial out-of-balance con- dition that causes the device to trip. This only checks the mechan- ics of the tripping operation, it does not check the condition of the electrical installation and hence is not a substitute for the tests discussed in Chapter There should be a notice in a prominent position at or near the origin of the installation where the device is located indicating that the test button should be operated quarterly.

For temporary installations it is recommended that this operation be carried out at more regular intervals. All other items of equipment such as switchgear, controlgear interlocks, etc. This could involve the operation of, for example, two-way switch- ing, dimmer switches, timers, thermostats, main isolators, circuit breakers, etc. BS is a little vague on exactly how this may be achieved, mentioning measuring circuit imped- ances or using calculations.

The voltage drop is probably best established by measuring the voltage at the origin and at the end of a particular circuit, subtracting the two and ensuring the drop does not exceed the values indicated in Table To ensure the safety of persons and livestock. To ensure protection of property from fire and heat. To ensure that the installation is not defective and complies with the current regulations.

However, that for an Initial Verification is preferred if possible. Periodic inspection and testing could be such a simple and straightforward process. Nevertheless it usually tends to be com- plicated and frustrating. It is usually only when there is a change of owner- ship that the mortgage companies insist on an electrical survey.

The worst cases are, however, industry and commerce. Periodic inspections are often requested by clients, reluctantly, to satisfy insurers or an impending visit by the HSE. Under the rare circumstances that an inspection and test is genu- inely requested due to responsible concerns for the safety of staff, etc.

When there are no drawings or items of information, especially on a large installation, there may be a degree of exploratory work to be carried out in order to ensure safety whilst inspecting and testing. If it is felt that it may be unsafe to continue with the inspection and test, then drawings and information must be produced in order to avoid contravening Section 6 of the Health and Safety at Work Act. A periodic inspection and test under these circumstances should be relatively easy, as little dismantling of the installation will be necessary, and the bulk of the work will be inspection.

Inspection should be carried out with the supply disconnected as it may be necessary to gain access to wiring in enclosures, etc. This is also the case when testing protective conductors, as these must never be disconnected unless the supply can be iso- lated. It is particularly important in the case of main protective bonding conductors which need to be disconnected in order to measure Ze.

Any aspects of the installation that may impair the safety of persons and livestock against the effects of electric shock and burns. That there are no installation defects that could give rise to heat and fire and hence damage property. That the installation is not damaged or deteriorated so as to impair safety. That any defects or non-compliance with the Regulations, which may give rise to danger, are identified. As was mentioned earlier, dismantling should be kept to a mini- mum as this process may create faults.

Hence a certain amount of sampling will be required. The amount of sampling would need to be commensurate with the number of defects being found. From the testing point of view, not all of the tests carried out on the initial inspection may need to be applied. This decision depends on the condition of the installation. The continuity of protective conductors is clearly important as are the tests for insulation resistance, loop impedance and oper- ation of RCDs, but one wonders if polarity tests are necessary if the installation has remained undisturbed since the last inspec- tion.

The same applies to ring circuit continuity as the L—N test is applied to detect interconnections in the ring, which could not occur on their own. It should be noted that if an installation is effectively supervised in normal use, then periodic inspection and testing can be replaced by regular maintenance by skilled persons.

This would only apply to, say, factory installations where there are permanent mainte- nance staff. This documentation is vitally important. It has to be correct and signed or authenticated by a competent person.

EICs and PIRs must be accompanied by a schedule of test results and a schedule of inspections for them to be valid. It should be noted that three signatures are required on an EIC, one in respect of the design, one in respect of the construction and one in respect of the inspection and test.

For larger installations there may be more than one designer, hence the certificate has space for two signatures, i. It could be, of course, that for a very small company, one person signs all three parts. Whatever the case, the original must be given to the person ordering the work, and a duplicate retained by the contractor. One important aspect of an EIC is the recommended interval between inspections.

This should be evaluated by the designer and will depend on the type of installation and its usage. In some cases the time interval is mandatory, especially where environments 67 CHH The rest of the form deals with the extent and limitations of the inspection and test, recommendations, and a summary of the installation.

The record of the extent and limitations of the inspec- tion is very important. It must be agreed with the client or other third party exactly what parts of the installation will be covered by the report and those that will not. The interval until the next test is determined by the inspector. With regard to the schedule of test results, test values should be recorded unadjusted, any compensation for temperature, etc.

Any alterations or additions to an installation will be subject to the issue of an EIC, except where the addition is, say, a single point added to an existing circuit, then the work is subject to the issue of an MEIWC. Summary: 1. A new installation or an addition or alteration that comprises new circuits requires an EIC. An existing installation requires a PIR. Note Points 2 and 3 must be accompanied by a schedule of test results and a schedule of inspections.

This ensures that future inspectors are aware of the installation details and test results which may indicate a slow progressive deterioration in some or all of the installation.

These certificates, etc. The following is a general guide to completing the necessary docu- mentation and should be read in conjunction with the examples given in BS and the IEE Guidance Note 3. Details of client: Name: Full name Address: Full address and post code Description: Domestic, industrial, commercial Extent: What work has been carried out e. Tick a relevant box. Next test: When the next test should be carried out and decided by the designer.

Live conductors: Tick relevant boxes CHH Supplier usually gives 16 kA Ze: From supplier or measurement. Supplier usually gives 0. Comments on existing installation: Write down any defects found in other parts of the installation which may have been revealed during an addition or an alteration. Details of client: Name: Full name could be a landlord, etc.

Extent and limitations: Full details of what is being tested extent and what is not limitations. If not enough space on form add extra sheets. Next inspection Filled in by inspector and signed, etc. Supply details As per an Electrical Installation Certificate. Observations Tick relevant box, if work is required, record details and enter relevant code 1, 2, 3 or 4 in space on right-hand side.

Summary Comment on overall condition. Only common sense and experience can determine whether satisfactory or unsatisfactory. Schedules Attach completed schedules of inspections and test results. Declaration Name, address, signature, etc. Contractor: Full name of tester. Date: Date of test. Signature: Signature of tester. Vulnerable Dimmers, electronic timers, CH controllers, etc. Address: Full, or if in a large installation, the location of a particular DB.

Earthing: Tick the relevant box. Ze at origin: Measured value. Confirmation of Tick box. Instruments: Record serial numbers of each instrument, or one number for a composite instrument.

Description: Suggest initial or periodic or whatever part of the installation is involved. For example, initial verification on a new shower circuit. Nothing to stop adding sheets to this form! Wiring conductors: Size of live and cpc, e. Tick box if ring L-N is OK.

X in a box if it has been inspected and is incorrect. Indicate three main areas, about which you would require information, in order correctly to carry out an initial verification of a new installation. There are various documents that are relevant to the inspection and testing of an installation, state: a one statutory item of documentation b two non-statutory items of documentation.

An Electrical Installation Certificate should be accompanied by signed documentation regarding three stages of an installation. What are these stages? Apart from wear and tear state three areas of investigation that you would consider when carrying out a periodic inspection and test of an installation. State three human senses that could be used during an inspection of an installation.

List the instruments which gave these readings. The following circuits are to be tested for insulation resistance. List the first three tests that should be carried out during an initial verification on a new domestic installation.

The test for the continuity of a cpc in a radial circuit feeding one socket outlet uses a temporary link and a milli- ohmmeter, state: a where the temporary link is connected. Where can you take this course? Find a centre. Find a course or qualification I'm looking for: Search.

Find a centre Near me:. Offering: Search. Centres Learners Employers. Qualifications explained. Requirements for Electrical Installations Information Documents. Last Updated: 10 Jan This qualification ensures that you are up-to-date with the latest industry regulation on wiring and the safe use and operation of electrical equipment and systems.

If you're a practising electrician, you must comply with the regulations for electrical work, this qualification is designed to provide those seeking progression in their career with the opportunity to develop the skills necessary to carry out job roles and responsibilities associated with the Electrotechnical industry. We are issuing digital credential to learners who have completed this qualification. General Information. Learners will complete one core unit: Requirements for electrical installations update to BS APL is available for those who have completed specific units under and Firstly however, to fully understand what is required, we need to consider some definitions from Part 2 of the Regulations.

Typically commercial installations will be under the control of a Skilled or Instructed Person. However domestic and some commercial installations will not. This is particularly important, as certain Regulations only apply to installations not under the supervision of a Skilled or Instructed Person.

A significant change is the introduction of Regulations requiring additional protection by RCDs. There are 3 points of consideration,. Certain Regulations only apply to installations not under the supervision of a Skilled or Instructed Person i.

Ordinary persons. The Regulations have introduced new requirements regarding socket outlets, particularly where used by ordinary persons e.

Home owners. The definitions for persons are important to consider when we look at the requirements for protection of circuits supplying socket outlets. Regulation Now under the requirements of the 17th edition it is likely that every socket outlet in a domestic installation will require RCD protection not exceeding 30mA. This may also apply to some commercial installations, like small offices or shops etc where there is no control on the use of those socket outlets.

Consideration should also be given to areas where free access to socket outlets is available to the general public e. Socket outlets for general use in a domestic installation require RCD protection not exceeding 30mA. Significant changes affect installations where cables are buried in the wall. This is the normal practice in dwellings. Here we need to consider Section , Selection and erection of wiring systems in relation to external influences. The particular requirements of this section apply to cables which are concealed in a wall or partition at a depth of less than 50mm, or where metal partitions are used.

The definitions for persons are once again important for this section. There are 5 options of installing cables in walls. The cables shall:. This is much the same as the 16th Edition requirements and the usual option is to install cables in a dedicated safe zone.

However, where an installation is not under the supervision of someone skilled or instructed, regulation