2. The risks Scope The zones Supplementary bonding Wiring systems Switchgear and controlgear Fixed current-using equipment Other equipment, example, washing machines. 601. OVERVIEW ON LOCATIONS CONTAINING A BATH OR SHOWER. 601. 2.
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2THE RISKSPersons in bathrooms are particularly at risk because of a reduction of body impedance due to:
a) lack of clothing, particularly footwearb) presence of water reducing contact resistancec) immersion in water, reducing total body resistanced) ready availability of earthed metale) increased contact area
requirements for bathrooms are to be met except that socket-outlets are allowed in bedrooms provided they are outside of zones 0, 1, 2 or 3 and protected by an RCD, also, Supplementary bonding, is only required in zones 1 and 2.
2.4 m 0.6 m
zone 3 zone 2 zone 1 zone 2 zone3
Figure showing Supplementary Bonding
in a bathroom – metal pipe installation
with soldered joints providing reliable electrical continuity
2Switchgear and Controlgear
601Fixed current-using equipment
Electric showers and electric shower pumps should comply with BS EN 60335-2-35 and BS EN 60335-2-41 respectively.
Usually suitable for installation within zone 1. Not required by BS 7671 to be protected by an RCD, however, often shower manufacturers recommend an RCD
Normal practice to provide an isolation switch within the bathroom. The switch must be installed outside zones 0, 1 and 2 although the cord of cord operatedswitches may reach into zones 1 or 2.
601Other Equipmenteg: washing machines and tumble dryers
Washing machines and tumble dryers may be installed in a bathroom (if suitable) provided they are:
6022. OVERVIEW ON LOCATIONS CONTAINING SWIMMING POOLS
2SUMMARY OF THE ADDITIONAL SUPPLEMENTARY REQUIREMENTS PLACED BY SECTION 602 OF BS 7671
area is divided into three zones, A, B
Examples of zone dimensions (plan) with fixed partitions of height at least 2.5 m
Dimensions in metres
r2= r1 - (s1 + s2)
r4= r3 - (s1 + s2)
r5= r3 - (s3 + s4)
zone A – IPX8 zone B – IPX5 – IPX4 – where water jets are not likely to be used for cleaningzone C – IPX2 – for indoor pools – IPX4 – for outdoor pools – IPX5 – where water jets are likely to be used for cleaning.
Fig 602A - Zone dimensions for swimming pools and paddling pools
Volume zone A
Volume zone A
Note: The dimensions are measured taking account of walls and fixed partitions
zone A – IPX8
zone B – IPX5
-IPX4 – where water jets are not likely to be used for cleaning
zone C – IPX2 – for indoor pools
- IPX4 – for outdoor pools
- IPX5 – where water jets are likely to be used for cleaning.
In zones A and B no surface metal conduit or trunking is allowed nor is the exposed metallic cable sheath of an armoured cable or an exposed earthing conductor.
Where a swimming pool forms part of a residence, all metalwork and pipes supplying the pool should be connected to an earth electrode and segregated from the rest of the building. An RCD should then be used to protect the supplies to the pool area and the swimming pool installation treated as part of the TT system.
Scope of section 603
The risk of electric shock is high on a
construction site because :
1. of the possibility of damage to cables and equipment
2. of the wide use of hand tools with trailing leads
3. of the accessibility of many extraneous-conductive- parts, which cannot practically be bonded
4. the works are generally open to the elements.
2Reduced Low Voltage Supplies for Construction Sites
BS 7671 requires the use of reduced low voltage supplies for all portable equipment, small mobile plant and local lighting up to 2 kW.
110 V reduced low voltage supplies with the centre point of the secondary winding of the step-down transformer earthed, limit the voltage to earth to 55 volts for single-phase supplies and 63.5 volts to earth for three-phase equipment
Limiting the voltage to 55 or 63.5 volts between a live conductor and earth effectively eliminates the risk of dangerous electric shock to exposed-conductive-parts
2Isolation and Switching
Section 604 repeats emergency switching requirements of Section 463 that emergency switching shall be provided on the supply to all the equipment from which it may be necessary to disconnect all live conductors in order to remove a hazard.
The requirement is to provide emergency switching where there is a need to remove a hazard, and the switching requirement is for
disconnection of all live conductors, that is including the neutral.
Every circuit supplying equipment shall be fed from a distribution
assembly complying with BS EN 60439-4 and BS 4363.
Protection against the weather and dust
Inspection and testing
integral test button). Should RCDs be used to protect portable
equipment they must be tested by the operative before each period
of use (using the integral test button) and by the responsible person
every 3 months (using an RCD tester).
Protection against indirect contact one of the following:
2Overview of Earthing Requirements for the Installation of Equipment having high protective conductor currents
2Overview of highway power supplies, street furniture and street located equipment
Inspection and Testing
(iv) polarity; this includes checks that single-pole control and protective devices (e.g. switches, circuit-breakers, fuses) are connected in the phase conductor only, that bayonet and Edison-screw lampholders (except for E14 and E27 to BS EN 60238) have their outer contacts connected to the neutral conductor and that wiring has been correctly connected to socket-outlets and other accessories (v) earth electrode resistance (vi) earth fault loop impedance (vii) prospective fault current, if not determined by enquiry of the distributor (viii) functional testing (including RCDs and RCBOs).
Tests should be carried out in the following sequence:
Before the supply is connected
(i) continuity of protective conductors, including main and supplementary bonding (ii) continuity of ring final circuit conductors, including protective conductors (iii) insulation resistance (iv) polarity (by continuity methods) (v) earth electrode resistance, when using an earth electrode resistance tester (see also vii).
With the supply is connected
(vi) re-check of polarity (vii) earth electrode resistance, when using a loop impedance tester (viii) earth fault loop impedance (ix) prospective fault current measurement, if not determined by enquiry of the distributor (x) functional testing.
ALTERATIONS AND ADDITIONS
THE ELECTRICAL INSTALLATION CERTIFICATE
an alteration or addition to an existing installation where new circuits have been introduced
PERIODIC INSPECTION REPORT
periodic inspection report - observations and recommendations.
3. The Future – 17th Edition
Typical wiring arrangement from shore to pontoon
Exhibition/show distribution with standby generator
Ceiling Heating Systems
Future changes in the 17th Edition
for Special Locations
Example of determination of the zones of a fountain
Reduced Low Voltage Supplies for Construction Sites
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