Low voltage
According to Approved Document P - Electrical safety – Dwellings: Low voltage is, ‘a voltage exceeding extra-low voltage, but not exceeding 1,000 V ac or 1,500 V dc between conductors, or 600 V ac or 900 V dc between conductors and earth.’ Where extra-low voltage is, ‘A voltage not exceeding 50 V ac or 120 V ripple-free dc, whether between conductors or to earth.’
The Illustrated Guide to Electrical Building Services, Third Edition (BG 31/2017), by David Bleicher & Peter Tse, published by BSRIA in 2014, suggests that: ‘Low voltage is a term used to describe 400 V three-phase and 230 V single-phase supplies. These are nominal voltages - the actual voltage may vary up to 10%. The intake to buildings that have a low voltage supply is usually provided by the electricity supplier in the form of an underground cable that emerges at a suitable point within the building. The cable is connected directly to the electricity supplier’s cut-out. Also known as a service head, this is a fused unit that protects the supplier’s infrastructure.’
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
Professional practical experience for Architects in training
The long process to transform the nature of education and professional practical experience in the Architecture profession following recent reports.
A people-first approach to retrofit
Moving away from the destructive paradigm of fabric-first.
International Electrician Day, 10 June 2025
Celebrating the role of electrical engineers from André-Marie Amperè, today and for the future.
New guide for clients launched at Houses of Parliament
'There has never been a more important time for clients to step up and ...ask the right questions'
The impact of recycled slate tiles
Innovation across the decades.
EPC changes for existing buildings
Changes and their context as the new RdSAP methodology comes into use from 15 June.
Skills England publishes Sector skills needs assessments
Priority areas relating to the built environment highlighted and described in brief.
BSRIA HVAC Market Watch - May 2025 Edition
Heat Pump Market Outlook: Policy, Performance & Refrigerant Trends for 2025–2028.
Committing to EDI in construction with CIOB
Built Environment professional bodies deepen commitment to EDI with two new signatories: CIAT and CICES.
Government Grenfell progress report at a glance
Line by line recomendation overview, with links to more details.
An engaging and lively review of his professional life.
Sustainable heating for listed buildings
A problem that needs to be approached intelligently.
50th Golden anniversary ECA Edmundson apprentice award
Deadline for entries has been extended to Friday 27 June, so don't miss out!
CIAT at the London Festival of Architecture
Designing for Everyone: Breaking Barriers in Inclusive Architecture.
Mixed reactions to apprenticeship and skills reform 2025
A 'welcome shift' for some and a 'backwards step' for others.