Almost all 13A RCD plugs available in the UK have a trip current rating of 30mA
The
30mA trip rating was decided on many years ago when RCDs first became
available and was the trip rating used because at the time many
electrical appliances were naturally quite leaky especially appliances
which contained Mineral insulated metal sheathed heating elements The
30mA trip level allowed reasonable immunity from nuisance tripping and a
good level of personal protection for the user
It is true that a
30mA RCD will protect you against dangerous shocks and prevent the
shock from causing fibrillation of your heart but it is still possible
for you to get a really nasty shock without the 30mA RCD tripping
You
could for example receive a shock of 20mA which would be very painful
and you may not be able to release your grip on the live part but the
30mA rcd would not trip
According to IEC60479, two key levels of electric current need to be considered with regard to shock protection.
The
first is the "let-go" level, which is generally accepted to be around
10mA. At or above this level, muscles may seize, and a person touching
or holding a live part may not be able to let go of the live part. RCDs
rated up to 10mA are intended for protection against "let-go" currents,
and are recommended for use in hospitals and old people's homes or
similar locations.
The second is the "fibrillation" level, which
is generally accepted to be around 50mA. At or above this level, heart
fibrillation is likely to occur. RCDs rated up to 30mA are the upper
limit for RCDs intended to provide shock protection.
These RCD plugs are 10mA rated so they will protect you against the let go level and the fibrillation level
If
the shock was so mild that 10mA was not reached this RCD would not trip
either but you would be below the let go level and could release you
grip on the live appliance
These plugs can be fitted to any
appliance in place of the normal 13A plug and will not nuisance trip on
any modern appliance as regulations require modern appliances to leak no
more than 0.3mA during normal operation.
Don`t get a nasty shock give yourself a much higher standard of personal protection with 10mA rcd plugs