The 6651C unit is suitable for front end of
building protection applications as
recommended by BS6651 : 1999 Annex C
location Category C. The protector provides
an economical means of preventing damage
to electrical installations from induced
voltage transients caused by switching or
nearby lightning strikes.
The 6651C unit provides three mode
system protection from mainsborne voltage
spikes and surges that can occur between
phase and neutral, phase and earth, neutral
and earth and additionally phase to phase
for the three phase model. This protection is
achieved by using high energy elements
which absorb or redirect incoming
mainsborne transients. Every unit has two
stages of protection, the status of which are
clearly indicated by lights incorporated in
the front panel, thus ensuring continuity of
protection by allowing time for replacement
once the first stage has ceased to protect.
Designed to be quickly and easily installed
alongside the incoming electrical supply panel,
the unit is connected in parallel with the mains
supply, thus eliminating complicated by-pass
wiring associated with series suppressors.
Connected in this manner the 6651C thereby
carries only the current associated with the
transient being discharged.
By connecting the 6651C ahead of a RCD the
incidence of nuisance tripping may be reduced.
The unit is suitable for direct connection
to a line rated up to 60 Amps but can be
connected via 60 Amp series fuses (BS 88
pt.2) for lines up to 100 Amps.
Since the 6651C should be installed as
close as possible to the distribution panel the
half metre cable supplied should be reduced
in length if possible and as appropriate.
The 6651C unit may be installed at any
angle to achieve minimum cable length, so
the cable entry may be at the top, bottom,
right or left of the housing.
The unit requires no maintenance other than
a routine examination of the status of the
lights and replacement if required.
The 6651C will automatically reset after
clamping surges up to the required 10kA
level and the Green light(s) indicates that
full protection is present.
clamping a number of 10kA surges the
energy handling capability of the unit's
first stage may be exceeded causing the
6651C's internal fuses to operate thus
safely disconnecting this stage.
light(s) will then also be illuminated and,
whilst the system will still be adequately
protected, the unit should be replaced
before a further large surge can remove
the second protection stage.
There is no
protection present when only the Red
light(s) is illuminated, but unprotected
mains power will still be supplied to the
Let Through Voltage
The let-through voltage of the 6651C,
including 0.5 metre of cable, is less than 900
volts in all modes when tested at 6kV 1.2/50us
o/c 3kA 8/20us s/c (i.e. as per BS6651: 1999
Annex C 13.6.1).
In accordance with BS6651: 1999 Annex
C 13.6.2, the 6651C unit does not affect the
in-line impedance, and the shunt
capacitance is minimal.
The 6651C unit includes internal fuses to
ensure that suppression components are
adequately protected in the event of violent
The Total Solution
The 6651C provides cost effective entry level
protection, ensuring that transient voltage
surges from external sources are held within
levels considered safe for sensitive
However, that's only
part of the solution. Air conditioners,
copiers, power tools, and a wide variety of
other electrical equipment can generate
destructive surges within a protected
So, don't settle for partial
Let us help you configure a
zoned solution that provides complete
protection at a very reasonable cost.