Useful References

Sintra · Apr 21, 2010

Current Carrying Capacity For PVC Sheathed Flat Cables With CPC (T&E)

A single T&E cable above a plasterboard ceiling covered by thermal insulation NOT exceeding 100mm thick
1.0mm - 13 amps
1.5mm - 16 amps
2.5mm - 21 amps
4.0mm - 27 amps
6.0mm - 34 amps
10.0mm - 45 amps
16.0mm - 57 amps

A single T&E cable above a plasterboard ceiling covered by thermal insulation exceeding 100mm thick
1.0mm - 10.5 amps
1.5mm - 13 amps
2.5mm - 17 amps
4.0mm - 22 amps
6.0mm - 27 amps
10.0mm - 36 amps
16.0mm - 46 amps

A single T&E cable in a stud wall with thermal insulation with the cable touching the inner surface of the wall
1.0mm - 13 amps
1.5mm - 16 amps
2.5mm - 21 amps
4.0mm - 27 amps
6.0mm - 35 amps
10.0mm - 47 amps
16.0mm - 63 amps

A single T&E cable in a stud wall with thermal insulation with the cable NOT touching the inner surface of the wall
1.0mm - 8 amps
1.5mm - 10 amps
2.5mm - 13.5 amps
4.0mm - 17.5 amps
6.0mm - 23.5 amps
10.0mm - 32 amps
16.0mm - 42.5 amps

A single T&E cable clipped direct
1.0mm - 16 amps
1.5mm - 20 amps
2.5mm - 27 amps
4.0mm - 37 amps
6.0mm - 47 amps
10.0mm - 64 amps
16.0mm - 85 amps

A single T&E cable enclosed in conduit in an insulated wall
1.0mm - 11.5 amps
1.5mm - 14.5 amps
2.5mm - 20 amps
4.0mm - 26 amps
6.0mm - 32 amps
10.0mm - 44 amps
16.0mm - 57 amps

A single T&E cable enclosed in surface mounted plastic conduit or mini trunking
1.0mm - 13 amps
1.5mm - 16.5 amps
2.5mm - 23 amps
4.0mm - 30 amps
6.0mm - 38 amps
10.0mm - 52 amps
16.0mm - 69 amps

Meter Tails

In conduit in a thermally insulating wall Ref method A
16mm = 61 amps,
25mm = 80 amps

In conduit on a wall or in trunking Ref method B
16mm = 76 amps,
25mm = 101 amps

Clipped direct Ref method C
16mm = 87 amps,
25mm = 114 amps

The values given in the above tables must be multiplied by the following values depending on the number of cables grouped together :
2 cables - 0.80
3 cables - 0.70
4 cables - 0.65
5 cables - 0.60
6 cables - 0.57

The formula for calculating the group rating factor for different sized cables grouped together is :1 / the square root of the number of the circuits in the group. 2.3.3.1
For more information see brb p268

DurhamSparky · Apr 21, 2010

Re: Current Carrying Capacity For PVC Sheathed Flat Cables With CPC (T&E)

i just use the TLC technical section and borrow there on-line calculator

but other than that Excellent thread!! going to print it off and keep it as a handy piece in my Bag

Sintra · Apr 22, 2010

Maximum Ze & Zs Values

BS 88-2.2 & BS 88-6 gG Fuses
5A : n/a
6A : 0.4s = 8.52, 5s = 13.5
10A : 0.4s = 5.11, 5s = 7.42
15A : n/a
16A : 0.4s = 2.70, 5s = 4.18
20A : 0.4s = 1.77, 5s = 2.91
25A : 0.4s = 1.44, 5s = 2.3
30A : n/a
32A : 0.4s = 1.04, 5s = 1.84
40A : 0.4s = n/a, 5s = 1.35
45A : n/a
50A : 0.4s = n/a, 5s = 1.04
60A : n/a
63A : 0.4s = n/a , 5s = 0.82
80A : 0.4s = n/a , 5s = 0.57
100A : 0.4s = n/a , 5s = 0.42
125A : 0.4s = n/a , 5s = 0.33
160A : 0.4s = n/a , 5s = 0.25
200A : 0.4s = n/a , 5s = 0.19

BS 1361 Fuses
5A : 0.4s = 10.45, 5s = 16.4
6A : n/a
10A : n/a
15A : 0.4s = 3.28, 5s = 5.0
16A : n/a
20A : 0.4s = 1.7, 5s = 2.8
25A : n/a
30A : 0.4s = 1.15, 5s = 1.84
32A : n/a
40A : n/a
45A : 0.4s = n/a, 5s = 0.96
50A : n/a
60A : 0.4s = n/a , 5s = 0.7
63A : n/a
80A : 0.4s = n/a , 5s = 0.5
100A : 0.4s = n/a , 5s = 0.36
125A : n/a
160A : n/a
200A : n/a

BS 3036 Fuses
5A : 0.4s = 9.58, 5s = 17.7
6A : n/a
10A : n/a
15A : 0.4s = 2.55, 5s = 5.35
16A : n/a
20A : 0.4s = 1.77, 5s = 3.83
25A : n/a
30A : 0.4s = 1.09, 5s = 2.64
32A : n/a
40A : n/a
45A : 0.4s = n/a, 5s = 1.59
50A : n/a
60A : 0.4s = n/a , 5s = 1.12
63A : n/a
80A : n/a
100A : 0.4s = n/a , 5s = 0.53
125A : n/a
160A : n/a
200A : n/a

BS 1362 Fuses
3A : 0.4s = 16.4, 5s = 23.2
13A : 0.4s = 2.42, 5s = 3.83

MCB's to BS EN 60898 & RCBOs to 61009-1 for disconnection times of 0.4 & 5
seconds
3A : typeB 15.33, typeC n/a, typeD n/a
5A : n/a
6A : typeB 7.67, typeC 3.83, typeD 1.92
10A : typeB 4.6, typeC 2.3, typeD 1.15
15A : n/a
16A : typeB 2.87, typeC 1.44, typeD 0.72
20A : typeB 2.3, typeC 1.15, typeD 0.57
25A : typeB 1.84, typeC 0.92, typeD 0.46
30A : n/a
32A : typeB 1.44, typeC 0.72, typeD 0.36
40A : typeB 1.15, typeC 0.57, typeD 0.29
45A : n/a
50A : typeB 0.92, typeC 0.46, typeD 0.23
60A : n/a
63A : typeB 0.73, typeC 0.36, typeD 0.18
80A : typeB 0.57, typeC 0.29, typeD 0.14
100A : typeB 0.46, typeC 0.23, typeD 0.11
125A : typeB 0.37, typeC 0.18, typeD 0.09

If the measured Zs value exceeds 80% of the given values, a more precise measurement may have to be made to satisfy the requirements of BS 7671. p361

BS7671 does not give maximum Zs values for BS 3871 mcb's.

If the maximum Zs value for a circuit in a TN system cannot be met, the circuit may be protected by a 30ma RCD. 531.3.1

If the maximum Ze value for a TN system cannot be met, the installation may be protected by a 100ma RCD and treated as a TT system. 531.3.1, 411.5.1, 411.5.2, 411.5.3

Maximum Zs values for non delayed RCD's to BS EN 61008-1 & 61009-1 for final circuits up to 32a in a TT system
30ma : 1667 ohms
100ma : 500 ohms
300ma : 167 ohms
500ma : 100 ohms

Maximum Ze values for TN-S & TN-C-S systems

Typical maximum values published by Public Electricity Suppliers
TN-S : 0.80 ohms
TN-C-S : 0.35 ohms

Sintra · Apr 22, 2010

International Protection Codes (IP Codes)

The degree of protection afforded by an enclosure is indicated by two numbers and followed by an optional two letters.

First Number - Degree Of Mechanical Protection
0 - not protected
1 - protected from solid objects exceeding 50mm
2 - protected from solid objects exxeeding 12mm
3 - protected from solid objects exceeding 2.5mm
4 - protected from solid objects excseding 1.0mm
5 - dust protected
6 - dust tight

Second Number - Degree Of Water Protection
0 - not protected1 - protected from dripping Water
2 - protected from dripping water when tilted up to 15 degrees
3 - protected from spraying water
4 - protected from splashing water
5 - protected from water jets
6 - protected from heavy seas
7 - protected from the effects of immersion
8 - protected from the effects of submersion

The letter X is used when a number is not required to be specified.

First Additional Letter
A - protected against access with the back of the hand
B - protected against access with a finger
C - protected against access with a tool
D - protected against access with a wire

Second Additional Letter
H - high voltage apparatus
M - tested for harmful effects due to the ingress of water when the movable parts of the equipment are in motion
S - tested for harmful effects dus to the ingress of water when the movable parts of the equipment are stationary
W - suitable for use under specified weather conditions and provided with additional protective features or processes

Sintra · Apr 23, 2010

SWA armour used as CPC

Table for using SWA as CPC figures in red do not comply.

View attachment SWA CPC Sizes.doc

Sintra · Apr 26, 2010

Fire detection grading.

The Grade System - is the system of engineering, not the level of protection.

Grade F - one or more battery powered smoke and heat alarms.

Grade E - a system of interlinked mains powered smoke and heat alarms with NO battery back up.

Grade D - a system of interlinked mains powered smoke and heat alarms with battery back up.

Grade C - a system consisting of smoke detectors and sounders (which may be smoke alarms) connected to a common power supply, comprising of mains power and a stand by supply with central control equipment

Grade B - fire detection and alarm system comprising of fire detectors (other than smoke alarms), fire alarm sounders and control and indicating equipment to either BS EN 54-2 and power supply to BS EN 54-4, or to Annex C of BS 5839 pt6.

Grade A - fire detection incorporating control and indicating equipment to either BS EN 54-2 and power supply to BS EN 54-4 installsd to BS 5839 : Pt 1 with some minor execeptions.

Grade D is required for new, owner occupied buildings of up to three storeys, two storey rented properties, and existing owner occupied buildings of up to two storeys. Very large storeys may require a Grade B alarm system.

Levels Of Protection

LD1 - a system installed throughout the dwelling, incorporating detectors in all circulation spaces that form part of the escape routes from the dwelling and in all rooms and areas in which fires may start, other than toilets, bath and shower rooms.

LD2 - a system incorporating detectors in all circulation spaces that form part of the escape routes from the dwelling, and in all rooms or areas that present a high risk of fire.

LD3 - a system incorporating detectors in all circulation spaces that form part of the escape routes from the dwelling.