11
1005759 ISS 1
Electrolytic corrosion will occur when dissimilar metals
that are in contact with each other create a potential
difference between themselves. Sometimes separated
by a conductive substance known as an electrolyte, the
dissimilar metals will create a small voltage (potential
difference) that allows the ions of one material to pass
to the other.
Just like a battery, ions will pass from the most positive
material to the more negative material.
Anything more than 0.3 volts can cause the most
positive material to degrade.
A swimming pool with its associated equipment
can create this effect. The pool water being an ideal
electrolyte and components of the filtration circuit,
heating system, steps, lights etc providing the dissimilar
metals needed to complete the circuit.
Whilst these small voltages are rarely a safety threat,
they can create premature failure through corrosion.
Not dissimilar to corrosion through oxidation, electrolytic
corrosion can cause complete failure of a metallic
material in a very short period of time.
In order to prevent this type of corrosion all metallic
components in contact with swimming pool water
should be bonded together using 10mm² bonding
cable. This includes non-electrical items such as metal
filters, pump strainer boxes, heat exchangers, steps
and handrails. It is highly recommended that bonding
be retrofitted to existing pools, which may not be
protected by this system.
All electrical work to be carried out in accordance with
l.E.E. regulations, latest issue, or local codes of practice
as applicable.
The machine should be installed in accordance with
EMC2004/108/EC.
Protected supply
fuses or motor type circuit breakers
(Type GU, FAZC) to specified rating, (see below). H.R.C.
fuses are recommended. An isolator which disconnects
all poles must be fitted within 2m and in line of sight of
the heat pump.†
All units must be correctly earthed- Grounded and an
earth leakage trip installed.
Inconsistent electrical supply
The following voltage limits must not be exceeded.
Failure to achieve the necessary voltages will invalidate
the warranty.
Minimum
Maximum
Voltage
Single phase machines
207V
253V
Cycle frequency (50Hz) 47.5Hz
52.5Hz
The voltage must not drop below the above figures
when starting the machine.
Note. This voltage must be available at the heat pump
whilst running.
† Note. The isolator must have a minimum of 3mm air
gap when turned off.
4�0 ELECTROLYTIC CORROSION IN SWIMMING
POOLS
4�1 ELECTRIC WIRING AND SUPPLY
