Electrical - Installation

3. Fill out everything you can on the certificate that you can. - It is taken for granted that you will complete this work today.

Obviously don't sign to say that you have considered the presence of danger notices etc if you haven't.

• • Client name

• Client address

• Contractor Details

• Installation address (if different)

• Extent of the installation covered by the certificate

• Comments on previous installation

• New Installation tick box

• Declaration and signature

• Recommendation for next inspection (probably 5 years if you've just completed it)

• References to any other documents forming part of the installation (Eg Smoke, Fire, Intruder Alarm Certificates, etc)

• Schedule of items to be tested

• Schedule of items to be inspected

• Estimated maximum demand - What is the estimated maximum electricity consumption of the property (If you are struggling, consider measuring the consumption of electricity over a period of time and basing your estimate on a figure related to that, perhaps double or triple that)4. You can now commence proving the system is dead and fill out the appropriate sections as you find out the fitting information.

• Location of cut-out

  • Supply characteristics - Is the supply TT, TNS or most commonly TNCS (PME)

  • Single phase or 3 phase - UK systems are very rarely 2 phase

  • Means of earthing (Earth spike, Supply or perhapds and type (Tape, Rod etc)

  • Material of conductor (Copper, steel etc)

  • Test instrument serial number/s (Most commonly contractors now use multi functional testers, so only 1 serial number is required)

Take out the main fuse*

• • Is it a BS88 cartridge fuse or perhaps a porcelain rewireable fuse

  • Does it specify what British Standard rating it is? (BS numbers may sometimes BOTH apply)

  • Nominal current rating ???????????

  • Short circuit capacity - 33kA is a typical SCC for an end user domestic single or 3 phase supply ?????????

  • Cross sectional area and type of meter tails and earthing conductors (Cable, Rod, Sizes etc)

While the supply terminals are open and revealed, you can perform your system tests.

• • Nominal voltage (UK single phase = 230v +/- 10%)

  • Actual voltage - Measured (Usually around 243 volts)

  • Frequency of supply - Usually 50Hz

  • Prospective fault current (PFC) and Prospective short circuit current (PSCC)

  • System Ze - Measured

  • Continuity of main earth and main equipotential conductors.

Before sealing the main fuse, main switch and completing the fusebox consider getting the following data.

• • BSEN (Standard) Number of casing and components

  • Voltage rating of components

  • Current and trip rating (if applicable)

  • No. of poles (usually single or double in the domestic environment)

Generally, the system will still allow for sufficient visual inspection to complete the rest of the paperwork during the live stages and completion but you should consider your particular circumstances as to whether it will be safer to ascertain further details before finalising the installation for inspection (Eg will the routing and cable types be easily recognizable once the terminations have been made)

Try to work methodically from one circuit to the next. These can all be determined via visual inspection and memory of installation methods.

• • Circuit number

  • Circuit descriptor

  • Type of wiring

  • Reference method

  • Number of points served by a circuit or fuse

  • Conductor CSA

You will need to consult reference materials for the following data.

• • Calculate the Maximum permitted disconnection time or refer to the table of "Rule of Thumb" values

  • Maximum permitted Zs permitted by BS7671

Before replacing covers and terminating connections, consider getting the following data from each circuit.

• • R1 + R2 reading from each ring circuit or conductor resistances gathered using the wander lead method

  • Continuity of Ring final circuits using the figure 8 method or simply measuring the continuities one by one

  • Insulation resistance tests - Beware of touching any metal work or conductors during this procedure.

  • Phase / Phase

  • Phase / Neutral

  • Phase / Earth

  • Neutral / Earth

Having completed the fusebox installation you can now perform your Live tests. Again, try to work methodically from one circuit to the next. As you finalize your readings you may choose to install light bulbs, switchgear etc in order to reduce labour and prepare for functional testing.

• • Polarity

  • RCD, RCCBO operating times

*Tampering with property belonging to the network operator is not permitted except on Health & Safety grounds. Should you consider that ascertaining the safety of the main fuse is a health & safety issue, you may do so. If you believe there is no potential threat to persons or property then you should contact the supplier and request that a representative attends the premises in order to disconnect the supply. You can then recall them to reattach the supply when the testing is complete. (This service is usually chargeable.)

If you discover that your installation's main fuse's seal is not intact, you can request your supplier to reseal it in order to avoid theft of supply. (This is usually a free service)