Electricity

Fuses – rating for 230 volt AC appliances

The requirement of Building Regulation part L is that reasonable
provision shall be made to limit heat loss through the
building fabric, hot water and hot air systems. In the case of
non residential buildings, provision must be made to limit solar
overheating and to provide energy efficient light systems.
To show compliance it is necessary to produce SAP (Standard
Assessment Procedure) energy ratings for buildings which can
be done in three ways:
an elemental method; a target U-value method and a carbon
index method.
The elemental method is suitable for small works and where it
is desired to minimise calculations. The requirement will be met
if the U-values of the elements do not exceed those listed
below and, in the case of dwellings, providing the area of windows,
doors and roof lights does not exceed 25% of the total
floor area.
In addition, the efficiency of the boiler in a dwelling must equal
or exceed the SEDBUK (Seasonal Efficiency of a Domestic Boiler
in the UK) ratings set out below. Note that the elemental
method cannot be used for buildings with direct electric heating.

The Water Supply (Water Fittings) Regulations 1999 supersede

the Water Supply Byelaws. Their aim is to prevent: waste,
misuse, undue consumption, contamination or false measurement
of water supplied by a Water Undertaker(WU). The
regulations should be read in conjunction with the WRAS
Guide, which includes detailed information of sizes, flow rates,
valves etc. Below is a VERY BROAD and BRIEF interpretation of
the regulations.

Application of the regulations

The regulations apply only to fittings supplied with water by a
WU. They do not apply to water fittings for non-domestic or
non-food production purposes providing the water is metered;
the supply is for less than 1 month (3 months with written
consent) and no water can return through a meter to a mains
pipe. They do not apply to fittings installed before 1 July 99.

Notification

Water undertakers must be notified of the following:
Erecting any building, except a pond or swimming pool of less
than 10,000 litres capacity
Altering any water system in non-residential premises
Changing the use of a property

Installing :

• A bath with a capacity greater than 330 litres
• A bidet with ascending spray or flexible hose
• A single shower unit with multi-head arrangement
• A pump or booster drawing more than 12 litres/min
• A water softener with a waste or needing water for
regeneration or cleaning
• A reduced pressure zone valve or any mechanical device
which presents serious health risks
• A garden watering system other than hand-held hose
• External pipes higher than 730mm or lower than 1350mm
• An automatically filled pond or swimming pool with a
capacity of more than 10,000 litres

Drainage

Foul drains
recommended minimum gradients
Peak flow Pipe size Minimum Maximum
l/s mm gradient capacity
l/s
< 1 75 1 : 40 4.1
< 1 100 1 : 40 9.2
> 1 75 1 : 80 2.8
> 1 100 1 : 80 * 6.3
> 1 150 1 : 150 † 15.0
Pipe Ø Gradient Pipe Ø Gradient
50 1 : 500 150 1 : 2160
75 1 : 860 175 1 : 2680
100 1 : 1260 200 1 : 3200
125 1 : 1680 225 1 : 3720
* Minimum of 1 WC † Minimum of 5 WCs
Land drains
in normal soils – minimum gradients
Traps
minimum sizes and seal depths
Appliance Ø trap Seal depth Ø trap Seal depth
mm mm mm mm
washbasin 32 75 waste disposer 40 75
bidet 32 75 urinal 40 75
bath* 40 50 sink 40 75
shower* 40 50 washing machine* 40 75
syphonic WC 75 50 dishwasher* 40 75
*Where these fittings discharge directly into a gully the seal depth may be
reduced to a minimum of 38 mm.