Part P Bathroom Zone Regulations 4 — Questions and Answers
Question 1: What is the maximum length of cable permitted for a connection in a bathroom zone between a ceiling rose and a pendant fitting?
- There is no specific maximum length, but the fitting must be appropriate for the zone and the flex must be rated for the temperature and use (Correct answer)
- Only rigid conduit may be used
- Maximum 0.5 m
- Maximum 2 m with an IP20 fitting
Correct answer: There is no specific maximum length, but the fitting must be appropriate for the zone and the flex must be rated for the temperature and use
There is no specific maximum length prescribed for a bathroom flex, but the luminaire and its connections must be appropriate for the zone conditions; pendant fittings should not hang into Zone 1 unless rated for Zone 1.
Question 2: Can a bathroom fan be installed in Zone 1?
- Yes, if it has a minimum IP rating of IPX4 and is specifically rated for Zone 1 installation (Correct answer)
- No fans may be installed in Zone 1
- Only fans supplied at SELV may be in Zone 1
- Only pull-cord operated fans are permitted in zones
Correct answer: Yes, if it has a minimum IP rating of IPX4 and is specifically rated for Zone 1 installation
Extractor fans with a minimum IPX4 rating and specifically rated for Zone 1 may be installed in Zone 1; many bathroom fans are designed and marked for installation in bathroom zones.
Question 3: What does the marking 'IP44' mean on an electrical accessory?
- Protected against solid objects greater than 1 mm diameter, and protected against water splashing from any direction (Correct answer)
- Protected against dust and immersion to 1 m depth
- Protected against solid objects greater than 50 mm only
- Fully dustproof and waterproof
Correct answer: Protected against solid objects greater than 1 mm diameter, and protected against water splashing from any direction
IP44: the first digit '4' indicates protection against solid objects greater than 1 mm (including wire and tools); the second digit '4' indicates protection against water splashing from any direction — suitable for Zone 2.
Question 4: Is a bathroom mirror light with integrated socket permitted in Zone 1?
- Only if it is a SELV shaver unit conforming to BS EN 61558-2-5 with appropriate IP rating for Zone 1 (Correct answer)
- Yes, any mirror light is permitted in Zone 1
- Yes, if it is at least 600 mm above the bath
- No mirror lights are permitted anywhere in a bathroom
Correct answer: Only if it is a SELV shaver unit conforming to BS EN 61558-2-5 with appropriate IP rating for Zone 1
Mirror lights with shaver sockets are only permitted in Zone 1 if they incorporate a SELV isolating transformer (BS EN 61558-2-5) and have an appropriate IP rating; standard socket-fitted mirrors cannot be in Zone 1.
Question 5: What does 'PELV' stand for and can it be used in bathroom Zone 0?
- Protected Extra Low Voltage — no, it cannot be used in Zone 0 because it is referenced to earth, which means a fault to earth in the water could be hazardous; only SELV is permitted (Correct answer)
- PELV is preferred over SELV in bathrooms
- PELV is the same as SELV for bathroom purposes
- PELV can be used in all bathroom zones
Correct answer: Protected Extra Low Voltage — no, it cannot be used in Zone 0 because it is referenced to earth, which means a fault to earth in the water could be hazardous; only SELV is permitted
PELV (Protected ELV) operates at extra-low voltage but has a connection to earth; in Zone 0, where the user is immersed in water, an earthed circuit could present a shock risk, so only SELV (separated from earth) is permitted.
Question 6: What is the purpose of the zone system in BS 7671 Section 701?
- To classify the relative risk of electric shock in different areas of a bathroom and specify the appropriate protection measures for each zone (Correct answer)
- To specify the minimum size of bathroom required
- To classify the water temperature zones
- To specify the required ventilation in each zone
Correct answer: To classify the relative risk of electric shock in different areas of a bathroom and specify the appropriate protection measures for each zone
The zone system provides a structured risk-based approach to electrical installation in bathrooms; the closer to the water, the higher the risk (and the higher the required protection level), allowing appropriate design of safe installations.
Part P Bathroom Zone Regulations 4
What is the maximum length of cable permitted for a connection in a bathroom zone between a ceiling rose and a pendant fitting?