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II. INSTALLATION
Joslyn P/N 1457-40
AC Surge Protector
The Joslyn AC Surge Protector P/N 1457-40 is intended for installation on power systems of
nominally 400Y/230 Vac, (220-250 Vac phase to neutral), 4 wires plus ground, 3 phase, grounded
wye, 50-60 Hz, unlimited kVA rating. It is intended to be installed at sites where there exists a
conductor interconnecting the neutral service conductor and protector ground.
Location: For shunt connected protectors (i.e.: in parallel across the service), locate the protector
on or as close to the service entrance cabinet as possible. It should be short-nippled directly to the
service cabinet and located so that the wires used to connect to the bus are as short as possible.
(The inductance of the wiring, about 1 micro Henry per meter, results in every 0.1 meter adding
about 100 volts to the suppression voltage of the protector on a typical 10 kA lightning surge.) If
the wire length exceeds .5 meter and very sensitive electronic equipment is to be protected, a sub-
panel rated surge suppressor should be connected 10 m or more downstream.
Mounting: The protector may be mounted in any position using the four φ 7.8 mounting holes.
See Figure 1 for protector dimensions.
Connections: Use the shortest and straightest path possible to shunt connect the protector to the
power system, avoiding sharp bends or loops in the wire. Twist the wires together if possible.
The protector should be connected directly to the bus on the load side of the main service
disconnect or subpanel. If no tap is available on the bus, it may be connected to a 60 amp circuit
breaker. A series connected protector can be located at any point on the load side of the main
service disconnect. See Figure 2.
Wire Size: The wire size for the power circuit connections should be 16 - 70 mm
(AWG No. 6 to
2
2/0).
30 mm
(AWG No. 2) is the maximum size necessary for shut connecting the protector.
2
Larger diameters can be used, but they will not result in any further measurable reductions in
resistance or inductance.
Connect the Ground wire to the lug provided inside the protector cabinet.
Connect the Neutral wire to the terminal marked "Neutral" on the metallic circuit board.
Measure the voltage between the neutral and ground terminal. There should not be any voltage.
If there is voltage, correct the wiring before installing any more wires.
Connect the 3 "hot" wires to the isolated terminals marked "Phase A", "Phase B", and "Phase C" in
any sequence.
If permitted by wire/service size (generally 100 A or less), the protector should be series
connected with the service wires entering and exiting the protector cabinet. The protector
terminals are double lugged for this purpose. This installation method eliminates inductive
overshoot from the shunt wiring method altogether. Refer to Figure 3.
MAG/MNL145740(A)
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