safety 7 - low voltage directive
TRANSCRIPT
8/6/2019 Safety 7 - Low Voltage Directive
http://slidepdf.com/reader/full/safety-7-low-voltage-directive 1/3
Safety Fact Sheet 7
To see lots more fact sheets like this one, or to register for our series of informative mini guides on related key topics – go to
www.reo.co.uk.
The small print: Every effort has been made to ensure the integrity of the information in this data sheet, which has been provided in goodfaith and the authors do not accept liability for any loss or damage caused by omissions, errors or the interpretation of the reader.
Types of Insulation
Primary Circuit (mains) Secondary Circuit
(ELV)
Secondary Circuit
(SELV)Earthed Metal
Case
Basic Insulation
Reinforced Insulation
Supplementary
Insulation
Operational
Insulation
The following information was kindly provided and compiled byKen Lawrence - Electrical Safety Consultant
(Tel: 01564 777914 Mobile: 07802 577764 Email: [email protected])
The Low Voltage Directive – Key pointsAll electrical equipment supplied in the European Economic Area must comply with the Low Voltage Directive(LVD). In UK law this is implemented through the Electrical Equipment (Safety) Regulations 1994 and it is a CEMarking requirement. It is not essential that testing for the LVD is carried out by a third party test house if themanufacturers are sufficiently confident of doing it themselves.
The safety standard covers equipment in normal use or in foreseeable misuse conditions and also applies toequipment built for own use by the manufacturer. It also covers prevention of access to hazards without theuse of special tools or a key. The regulations do not apply to explosive atmospheres, medical equipment,aircraft, ships, railways, lifts, electricity meters, domestic plugs and sockets or components. However, there areother Directives or Regulations that apply to these items
Voltages covered by the LVD are 50 – 1000 Vac (rms) and 75 – 1500 Vdc. However, there is some discussion
at the moment about reducing the minimum to zero volts.
General requirementsAdditionally the following should be considered
Voltages greater than 30 Vac or 60 Vdc are normally considered to be hazardous
Voltages greater than 2V with available power greater than 240VA are considered to be hazardous energylevels.
It must not be possible, under normal or single fault conditions, to make contact with hazardous voltages or hazardous energy levels.
Accessibility to Electrical Hazards There must be two levels of protection between hazardous voltages and “safe” voltages. This can be made
up of one layer of insulation plus earth or two layers of insulation. The first layer of insulation is known as Basic Insulation. There will be Basic Insulation between hazardousvoltages and earth or earthed parts.
If there is not an earth a second layer of insulation is required and this is known as Supplementary Insulation.
A combination of Basic Insulation and Supplementary Insulation is known as Double Insulation.
Often there is a single layer of insulation between hazardous and “safe” voltages which has the sameinsulation properties as Double Insulation, this is known as Reinforced Insulation.
page 1 of 3
8/6/2019 Safety 7 - Low Voltage Directive
http://slidepdf.com/reader/full/safety-7-low-voltage-directive 2/3
Safety Fact Sheet 7
To see lots more fact sheets like this one, or to register for our series of informative mini guides on related key topics – go to
www.reo.co.uk.
The small print: Every effort has been made to ensure the integrity of the information in this data sheet, which has been provided in goodfaith and the authors do not accept liability for any loss or damage caused by omissions, errors or the interpretation of the reader.
Insulation Distances
Insulation distance through air is known as the Clearance Distance.
Insulation distance along a surface is known as the Creepage Distance. Assuming the hazardous voltage is 230V single phase mains, the following table shows the normalinsulation distances:
Clearance Creepage Distance through insulation Stress Voltage
Basic Insulation 2.0 mm 2.5 mm Not Specified1.5 kVac
(2.1 kVdc)
Double or reinforcedinsulation
4.0 mm 5.0 mm 0.4 mm3.0 kVac
(4.2 kVdc)
Examples of Creepage Distances and Clearances
Creepage Distances
and Clearances (1)
≥1mm <1mm
Clearance
Creepage Distance
Creepage Distances
and Clearances (2)
Clearance
Creepage Distance
L
N
F1
R1
L1
R2
C1
F2
D1 D4D3D2
R3
R4
C2+ +
+ +
+
RL1
T1
OC1
Creepage Distance (1)
Basic insulation - creepage distance at least 2.5mm
between protective earth and hazardous circuitry.
Reinforced insulation - creepage distance at least 5mm
between hazardous circuitry and selv circuitry.
Creepage Distance (2)
Basic insulation - creepage distance at least 2.5mm
between protective earth and hazardous circuitry.
There must still be a creepage distance of at least 5mm to maintain
reinforced insulation between hazardous circuitry and selv circuitry
even though the earth track separates the two circuits.
Note:
L
N
F1
R1
RL1
T1
OC1
C1
F2
D1 D4D3D2
R3
R4
C2+ +
+ +
+
L1
R2
8/6/2019 Safety 7 - Low Voltage Directive
http://slidepdf.com/reader/full/safety-7-low-voltage-directive 3/3
Safety Fact Sheet 7
To see lots more fact sheets like this one, or to register for our series of inf ormative mini guides on related key topics – go to
www.reo.co.uk.
The small print: Every effort has been made to ensure the integrity of the information in this data sheet, which has been provided in goodfaith and the authors do not accept liability for any loss or damage caused by omissions, errors or the interpretation of the reader.
T1
OC1F1 R1 R4
hazardous circuitry
selv circuits
at least
4mm
Clearance Distance
Reinforced insulation - clearance distance at least 4mm
between selv circuitry and hazardous circuitry.
Distance through
Insulation
Mains Mains
SELV SELV
2 or 3 layers
of tape
Distance throughSolid Insulation
Insulation in
thin layers
Creepage
Distance
Other important considerations
Earthing Earth wiring must be green/yellow (bare or transparent covering is allowed
for earth braiding).
The resistance between any point that requires to be earthed for safety
reasons and the earth terminal must be less than 0.1Ω.
The primary earth connection must be marked , subsequent earths
should be marked .
The primary earth should preferably be connected to a separate terminal,
subsequent earths being taken from another terminal. If this is not possible
the primary earth should be connected firstand held in p lace with a nut, subsequent
earths can then be added and held in place
with a second nut. The reason for this is to
prevent the main earth from being disturbed
during servicing.
PrimaryEarth
To other earth points
Earthing Earth wiring must be green/yellow (bare or transparent covering is allowed
for earth braiding).
The resistance between any point that requires to be earthed for safety
reasons and the earth terminal must be less than 0.1Ω.
The primary earth connection must be marked , subsequent earths
should be marked .
The primary earth should preferably be connected to a separate terminal,
subsequent earths being taken from another terminal. If this is not possible
the primary earth should be connected firstand held in p lace with a nut, subsequent
earths can then be added and held in place
with a second nut. The reason for this is to
prevent the main earth from being disturbed
during servicing.
PrimaryEarth
To other earth points
Rating Plate
ACH-6X
INPUT AC 100 - 240 V
180 mA 50 - 60 HzOUTPUT DC 10 V, 740 mA
Indoor use only
Made in Germany
SN 00074884/CD11/560
SMITHEN®
A rating plate must be affixed to the
equipment in a visible position
Rating Plate
ACH-6X
INPUT AC 100 - 240 V
180 mA 50 - 60 HzOUTPUT DC 10 V, 740 mA
Indoor use only
Made in Germany
SN 00074884/CD11/560
SMITHEN®
ACH-6X
INPUT AC 100 - 240 V
180 mA 50 - 60 HzOUTPUT DC 10 V, 740 mA
Indoor use only
Made in Germany
SN 00074884/CD11/560
SMITHEN®
A rating plate must be affixed to the
equipment in a visible position