SECTION 1 INSTALLATION
1--1
ASCO Series 300 AutomaticTransfer Switches (ATSs)are
Listed under Underwriters Laboratories UL 1008 Standard
for Safety for Automatic Transfer Switches. Series 300s are
also Listed under CSA C22.2 No. 178 Standard for ATSs.
All control features are UL Component Recognized, which
assures that ASCO automatic transfer switches meet
OSHA Safety Requirementsand will be acceptable to
electrical inspectors.
ASCO Series 300Automatic Transfer Switchesare
suitable for emergencyand standby system applications.
They meet emergencysystem rating requirements as
defined in Nation al Electrical Code (NEC) Article 70 0
and UL 1008. Also, they are suitable for the
requirements of NEC Article517 – Health Care
Facilities,NEC Article 701 – Legally Required Standby
Systems, NEC Article 702 – Optional Standby Systems,
NFPA99 Health Care Facilities, and NFPA 110
Emergency and Standby PowerSystems.

Rating Label

Each automatic transfer switch contains a rating label to
define the loads and fault circuit withstand / closing ratings.
Refer to the labelon the transfer switch for specific values.
Do not exceed the values on the rating label.
Exceeding the rating can cause personal injury
or serious equipmentdamage.
Series 300 AutomaticTransfer Switches are factorywired
and tested. Installationrequires skid removal then
securing the enclosure to the supporting foundation.

Remove the Shipping Skid

Openthe front door and remove the four lagscrews (two in
front,two in rear) securing the enclosure to the wood skid.

Supporting Foundation

The supportingfoundation for the enclosure must be
level and straight. Refer to the applicable enclosure
outline drawingincluded with the Series 300 for all
mounting details including door opening space.
If bottom cableentry is used, the foundation must be
prepared so that the conduitstubs are located correctly.
Referto the enclosure outline drawingfor specified area
and location. Providecable bending space and clearance
to live metal parts.When a concrete floor is poured, use
interlocking conduit spacer caps or a wood or metal
template to maintainproper conduit alignment.

Mounting

Refer to the applicable enclosureout line drawing
furnished with this switch and mount the Series 300
accordingto details and instructions shown on diagram.

Auxiliary Cable Box for 1000–2000 amp

An auxiliary cablebox is required if the power cables do
not enter the enclosure directly adjacent to the terminal
lugs (for example,if all power cables enter the top or
bottom). Order ASCO part no. 609027 if needed.
Do not route thepower cables along
the sides of the Transfer Switch.

Line Connections

Refer to the Wiring Diagram provided with your Series
300 ATS. Allwi ring must be made in accordance with
the National Electri cal Code and local codes.
It is unnecessary to remove pole covers from the transfer
switch. Ifyou do remove them, reinstall them carefully.
De–energize the conductors before making any
line or auxiliary circuitry connections. Be sure
that Normal and Emergency line connections
are in proper phase rotation. Place engine gen-
erator starting control in the OFF position. Make
sure engine generator is not in operation.

Testing PowerConductors

Do not connect the power conductorsto the Series 300
transfer switchuntil they are tested. Installing power
cables in conduit, cable troughs and ceiling-suspended
hangers often requiresconsiderable force. The pulling
of cables candamage insulation and stretch or break the
conductor’sstrands. For this reason, after the cables are
pulledinto position, and before they are connected, they
should be testedto verify that they are not defective or
have been damaged during installation.
Protect theswitch from construction grit
and metal chips to prevent malfunction or
shortened life of the automa tics witch switch.

Connecting Power Conductors

After the power cableshave been tested, connect them
to the appropriate terminallugs on the transfer switch as
shown on the wiring diagram provided with this Series
300. Make sure the lugs provided are suitable for use
with the cables beinginstalled. Standard terminal lugs
are solderless screw type and will accept the wire sizes
listed on the drawings provided with the Series 300. Be
careful whenstripping insulation from the cables; avoid
nicking or ringing the conductor. Removesurface oxides
from cables by cleaning with a wire brush. When
aluminum cable is used, apply joint compound to
conductors. Tighten cable lugsto the to rque specified
on rating label.