Regulation 434.5.1
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Yes i do Canoe. The pfc is the maximum current that is allowed to flow should a fault occur between live conductors and live conductors and earth.
Where I am confused is under the reg 434.5.1 second paragraph, where it stated "these devices" is it talking about the supply side device or load side.
To me it reads in the first paragraph that the load side device can have a lesser pfc rating than the supply side device and then at the end of the second paragraph it then sounds like the device on the load side must be as great or greater than the supply side device.
Where I am confused is under the reg 434.5.1 second paragraph, where it stated "these devices" is it talking about the supply side device or load side.
To me it reads in the first paragraph that the load side device can have a lesser pfc rating than the supply side device and then at the end of the second paragraph it then sounds like the device on the load side must be as great or greater than the supply side device.
Technician
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The let-through energy is the square of the
fault current multiplied by the time for
which it is allowed to flow during disconnection.
The device installed on the supply side refers
to something called back-up protection.
The let-through energy of the upstream device
must not exceed the rated short circuit capacity
of the one on the load side of that device.
This is how it is IIRC.
fault current multiplied by the time for
which it is allowed to flow during disconnection.
The device installed on the supply side refers
to something called back-up protection.
The let-through energy of the upstream device
must not exceed the rated short circuit capacity
of the one on the load side of that device.
This is how it is IIRC.
Sherlock Ohms
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This regulation relies heavily on annexe Za of BS 60439 in order to be correct.
"Part 3 of the Standard, BS EN 60439-3, deals with the particular
requirements for low voltage switchgear and control gear
assemblies intended to be installed in places where unskilled
persons have access to their use. This covers the supplementary
requirements for enclosure distribution boards suitable for indoor
use containing protective devices intended for use either in
domestic applications or other locations where unskilled persons
have access. Control and/or signalling devices may also be
included.
These distribution assemblies are for use on AC supplies, with a
nominal voltage to earth not exceeding 300V. The outgoing
circuits include short circuit protective devices, each having a
rated current not exceeding 125A with a total incoming load
current not exceeding 250A.
In the UK, such equipment is referred to as a
"Part 3 of the Standard, BS EN 60439-3, deals with the particular
requirements for low voltage switchgear and control gear
assemblies intended to be installed in places where unskilled
persons have access to their use. This covers the supplementary
requirements for enclosure distribution boards suitable for indoor
use containing protective devices intended for use either in
domestic applications or other locations where unskilled persons
have access. Control and/or signalling devices may also be
included.
These distribution assemblies are for use on AC supplies, with a
nominal voltage to earth not exceeding 300V. The outgoing
circuits include short circuit protective devices, each having a
rated current not exceeding 125A with a total incoming load
current not exceeding 250A.
In the UK, such equipment is referred to as a
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