construction services building standards for mechanical ... · the purpose of this document is to...

Construction Services

Building standards for mechanical and electrical installations Utilities and existing services Version 1.0 October 2012

Directorate: Environment

Construction Services - Building standards for mechanical and electrical installations Utilities and existing services Contents 1.0 Introduction

1.1 Purpose of document 1.2 Standards generally 1.3 Deviation from standards

2.0 Utilities and existing services generally 3.0 Legislation, regulations and advice documents 4.0 New utility supplies 5.0 Existing infrastructure 6.0 Incoming electric supplies 7.0 Gas service safety

7.1 Building over gas services 8.0 Isolation of services 9.0 Underground Electrical Services

9.1 Cables installed underground 9.2 Underground cable ducts

10.0 Excavation Works 11.0 Records

Construction Services Building Standard– M&E-Utilities and existing services 2 Version 1.0

1.0 Introduction

1.1 Purpose of document The purpose of this document is to provide information regarding Cornwall Council’s common standards, policies and requirements for building services to external Framework Consultants, Lead Consultants/Designers, Mechanical and Electrical (M&E) Services Design Engineers, Design and Build Contractors, M&E Contractors, M&E sub-Contractors, Specialists and Suppliers. This document does not seek to replace industry-standard design guidance or practice. It is intended to provide designers with the Council’s specific standards and requirements, which are to be used as the basis of all building construction. Although this document describes particular standards it is to be read in conjunction with all other supporting building works project specific requirements and documentation. External Framework Consultants, Lead Consultants/Designers, M&E Services Design Engineers, Design and Build Contractors, M&E Contractors, M&E sub-Contractors, Specialists and Suppliers will be expected to comply with the following requirements when preparing any schemes for building construction works for all new build, extensions, refurbishment, maintenance and decommissioning works. 1.2 Standards generally Cornwall Council has a significant property portfolio, which may require new, refurbishment, maintenance or demolition works to be carried out to meet a variety of requirements for various types of end users. This document describes the employer’s particular requirements for utilities and existing services that M&E consultants/designers will be responsible for completing, mechanical and electrical services installations, to any building construction works. M&E consultants/designers are advised that any standards set by the client team are intended to assist the design process only and the adequacy and suitability of any information indicated there upon must be confirmed by the consultants. Modern construction methods offer a wide range of materials and methods to create solutions for buildings. The majority are suitable and work well to provide an appropriate environment for the lifespan of the project and their efficacy can only be judged on a project-by-project basis at the design reviews or during the approval process. However, the following is fundamental issues which should be addressed to ensure that the preferred solution offers compliance to the Council’s expectations.


• All works will be expected to meet the requirements of the Construction (Design and Management) Regulations 2007, as well as applicable Health and Safety legislation to execute the works on site.

• The installation of a compatible building energy management system, allowing connection to core monitoring will be required. The provision of information technology systems shall comply with the existing policies of the Council.

• The choice of materials for building designs, construction, maintenance, refurbishment and decommissioning works, are to be selected with particular reference to their ease of use, frequency of maintenance, ease of upgrading or renewal and their ability to offer future flexibility and adaptability.

• Production of appropriate drawings and documentation, identifying and measuring the works to be undertaken are essential to ensure that the Council’s representatives can clearly identify and consider all materials, components and services involved in the project before the works are undertaken.

• All materials shall comply with the relevant British and European Standards (BS/BS EN) where applicable and for materials not of UK manufacture, the relevant certificates of compliance will be required. Maximum use is to be made of re-used, re-useable, recycled and recyclable materials or renewable materials from sustainably managed sources in order that any environmental impact is kept to a minimum, with low carbon footprint materials used where practical.

• Building construction techniques, material selections, services installations and finishes shall all represent the need to offer good value for money, and offer a solution that provides minimal environmental impact, good life expectancy and low maintenance.

1.3 Deviation from standards Should designers and/or providers of building construction, maintenance, refurbishment and decommissioning works find it necessary to incorporate alternative standards or requirements to those stated within the following document or any other Council building construction standards then approval shall be sought in writing from the relevant Cornwall Council representative. Designers and/or providers of building construction works will be required to justify and demonstrate, with written documentation, that the alternative proposals will provide equivalent or better performance, result in the same or improved whole life costing and be of equal or better value. 2.0 Utilities and existing services generally Designers will be required to carry out all negotiations with the appropriate Statutory Authority, or the Council’s current supplier, for water, gas and electrical supplies to the site. All new and modified gas, electricity and water supplies are currently procured through the Council’s Energy Management Unit.


All new meters shall be of a type which provides an electrical pulsed output and compatible with the Council's Automatic Meter Reading (AMR) strategy. The designer is also responsible for checking the capacity of existing services where the building is on an existing site, and for negotiating any upgrading required. Attention is drawn to the extended delays which are frequently encountered when dealing with gas, electricity and water undertakings and their sub-contractors, and designers are reminded of the need to initiate the process as soon as possible after the instruction to proceed is confirmed. Payments are normally forwarded direct to the supply undertaking by the Council, but the Designer in collaboration with the statutory supplier shall forward to the council with a request to raise an order and issue payment. Designers need to allow adequate time for this process. 3.0 Legislation, regulations and advice documents Various regulations, codes, standards and guidance on utilities and existing services are applicable and these include the following:- • The Utilities Act 2000 • The Electricity Act 1989 (amended by the Utilities Act 2000) • The Electricity (Standards of Performance) Regulations 2005 • The Electricity at Work Regulations 1989 • The Electricity Safety, Quality and Continuity Regulations 2002 • The Gas (Standards of Performance) Regulations 2002 • The Gas Safety (Installation and Use) Regulations 1998 • The Water Industry Act 1991 • The Water Regulations 1999 • The Competition Act 1998 • The Fair Trading Act 1973

4.0 New utility supplies Where an electricity supply is required for a green field site and the utility does not exist, the Council requires that this be processed through the Energy Management Unit. Where existing utilities are in place consultants/designers are required to contact the existing supplier and ensure the service is suitable, with sufficient capacity for its use. 5.0 Existing infrastructure New, alteration and refurbishment proposals can increase the demands on existing site services. Checks must be made early in the design stage to ensure that the services can cope with this increased load. A survey of the existing services is to be made and a report provided on the implications to the existing services and controls, and cost of the project.


Some records of existing services may be available but these are not guaranteed. It may be necessary to encompass alterations and upgrading of the existing services. On existing sites, some record drawings may be available for use by the Designer. Arrangements can be made with the Property Services to view those that exist, and copies of any selected can be made available. No guarantee can be given that a drawing exists for any particular site, or that if they do exist that the information is correct. The consultant / designer must be responsible for obtaining any information required for the project from his own site survey. Any extension of an existing service / system must be compatible with the existing, and preferably incorporate equipment of the same or similar manufacture. 6.0 Incoming electric supplies Selection of the appropriate Electricity Suppliers tariff must be the most economical one is supplied, with particular reference to load, annual usage, and potential for off-peak use. Electricity is purchased via the Council’s Energy Management Unit, who run the contract on behalf of the Council. Electrical consultants/designers shall be responsible for assessing the adequacy of existing incoming mains supplies to support any planned increase in electrical load for the proposed development. This should be undertaken as part of the initial feasibility or outline design in order to permit up rated supplies to be procured in good time if necessary. Consultants/designers should commission a load measurement exercise where necessary to establish the existing load, the cost of this exercise being identified and incorporated within the Consultants/designers fee bid or project cost plan whichever is the more appropriate. It has been found on many projects that the electrical installations have pierced the vapour barrier provided in the roofs. All designs for electrical works must ensure that conduits and other fittings are positioned such that the vapour barrier in any building construction is not pierced, other than for fixings, and where these fixings occur their exact arrangement must be agreed with the lead consultant/designer 7.0 Gas service safety Consultants/designers to provide line diagrams of gas mains for all new build and update existing line diagrams for all alteration works. Provide copies of line diagrams as follows:

• A copy to head of the establishment • A copy in the health and safety files • A copy shall be retained by the consultant/designer


• A copy shall be fixed adjacent to the gas meter.

7.1 Building over gas service Consider the implications of Gas Safe Register ensuring that gas service pipes are not built over or gas meters enclosed. 8.0 Isolation of existing services Special areas such as laboratories and workshops, etc. shall be provided with special means of isolation. In general, this means a single control panel in each room allowing individual or group isolation of gas, water and electrical outlets within the room. Gas proving shall be incorporated, and the electrical isolation shall extend via a contactor to any safety isolating transformers. Domestic hot water circulation systems shall not be isolated. Teacher's workstations in Schools may require a dedicated permanent water supply for safety purposes. School prep rooms serving laboratories are not normally served via isolating systems. All water installations serving laboratories shall comply with the Water Supply (Water Fittings) Regulations 1999 and non-potable water supplies to laboratory taps shall be from derived from gravity or pumped storage. Alternatively, approved laboratory taps suitable for direct connection may be used by installing approved pipe interrupters on each laboratory tap outlet to provide a permanent Type A air gap. 9.0 Underground electrical services 9.1 Cables installed underground All cables which run underground, whether installed in duct or direct in the ground should be suitable for external use. A yellow cable marker tape with the words ‘Caution electric cable below’, should be installed directly above the cable route at a depth of approximately 225mm. Cable marker tape should also be laid along the route of all buried electrical services ducts where it is considered that they are likely to be disturbed in the future. Where necessary PVC and, XLPE armoured power cables may be buried direct in the ground but should be installed to the manufacturer’s recommendations and in accordance with the IEE Wiring Regulations. The cables shall be laid at a suitable depth in a bed of sand and covered with sand before backfilling is carried out. At service entry points and where underground cables traverse roads, pathways, hard play areas etc. cables shall be installed within adequately sized ducts to permit future removal without disturbing the surface above. Where control, alarm, CCTV, communications or IT cables are to be run underground they should be installed within a system of ducts and draw


pits, to provide protection to the cables and permit further cables to be installed in the future. 9.2 Underground cable ducts Underground cable ducts should generally be 100mm diameter twin walled high-density polyethylene with smooth interior and corrugated exterior for extra strength. • Lengths should interlock and provide a smooth internal joint. • A draw rope should be installed to enable the pulling in of cables. • Ducts should be laid to fall in free draining trenches and backfilled with

all sharp material and foreign matter removed. • Draw ropes should be attached at each end to prevent them being

inadvertently pulled through with other cables. • Wherever ducts are to be installed one spare duct should be provided

as a contingency for future use. Ducts should be colour coded for identification purposes as follows: • Black - Electrical services • Grey - Communications and IT • Green - CCTV • Orange - Street lighting Dedicated ducts and draw pits should be installed for fibre optic cables. All ducts should be installed to the manufacturer’s recommendations. After cable installation each opening to the duct should be plugged to prevent the ingress of water and vermin. Ducts should be fire stopped at the final entry point into the building. Where changes of direction are required draw pits of a suitable size should be provided and installed. These should be standard prefabricated units or purpose built brick chambers of suitable size and depth for easy cable installation taking into account the likely bending radius of the cables. All draw pits and cable chambers should be provided with weather tight inspection covers fitted with tamperproof fixings. Where installed in areas where vehicular traffic is likely they should be fitted with heavy duty inspection covers. 10.0 Excavation works Before any excavation takes place reference should be made to any available record drawings of existing underground services. The proposed routes should be then be swept with a cable / services locator to ascertain as far as possible whether any existing services are likely to be disturbed.


The recommendation of HSE Guidance note HSG 47- Avoiding danger from underground services should be observed.

Temporary barriers, tapes and warning signs should be used to segregate any open trench whilst work is being carried out. 11.0 Records Before the underground services are buried their positions should be accurately measured and the routes and depths should be marked on a record drawing and passed to the client with the other Maintenance, Record and Safety Information.

Prepared by:

Strategic Planning and Standards Property Services email sp&[email protected] Draft Date Prepared By 1.0 10/10/12 CJ


mailto:sp&[email protected]


If you would like this information in another format please contact:

Cornwall Council County Hall Treyew Road Truro TR1 3AY

Telephone: 0300 1234 100

Email: [email protected]

www.cornwall.gov.uk

mailto:[email protected]

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