Answar of Barrett Farm Foods

Electrical Infrastructure[pic 1]

Specification for Electrical Installation Practice

1. Fabrication and Fixing to Structural Steelwork

Structural steelworks shall not be drilled, unless specifically indicated on construction drawings

1. Circuit Charts

Distribution boards shall be fitted with distribution circuit charts installed inside each distribution board.  These charts shall consist of a typed list giving both designation of each circuit and rating of each circuit fuse or circuit breaker.  Labels shall also be attached to all barriers of fuses or circuit breakers, indicating identification number of each individual circuit shown on distribution circuit chart.

1. Requirements for cable jointers

All cable jointers shall possess a valid jointers certificate signed and issued by the CFDH, Electrical.

Earthing

1. Earth Electrodes

Extensible earth rods shall be installed in accordance with the Standard Electrical Drawings to a minimum depth of 4.8 metres.

1. HAZARDOUS AREA

Zone 0        -Flammable atmospheres are continuously present or present for long periods. Electrical equipment shall not be installed for use in Zone 0 areas.

Zone 1        -        Flammable atmospheres are likely to occur in normal operation.

Zone 2        -        Flammable atmospheres are not likely to occur in normal operation and if they occur will only exist for a short time.

SP 1109 Specification for Earthing and Bonding

1. Conventions for Transformer Winding Arrangements

An upper-case letter indicates the higher voltage winding

A lower-case letter indicates the lower voltage winding

Y or y indicates a star winding

D or d indicates a delta winding

Z or z indicates a zigzag winding

N or n indicates that the star winding has an accessible neutral point

Example:        Dyn is a transformer with a delta HV winding and a star LV winding with accessible neutral point

EARTHING SYSTEMS

The IEE Regulations using the letters (T, N, C, S) these letters stand for:

T - Terre its means earth in French and meaning a direct connection to earth. 

N - Neutral

C - Combined

S - Separate.

• The first letter denotes the earthing arrangement at the source of energy:

T        =        direct connection of one or more points to Earth.

I        =        all live parts isolated from Earth or one point connected to Earth through an impedance.

• The second letter denotes the relationship of the exposed conductive parts of the installation to Earth:

T        =        direct electrical connection of the exposed conductive parts to Earth independently of the earthing of any point of the source of energy,

N        =        direct electrical connection of the exposed conductive parts to the earthed points of the source of energy, which for AC, is usually the neutral point.