EPS-3PSW-MMS
SAVE THESE INSTRUCTIONS FOR FUTURE REFERENCE
The Larson Electronics EPS-3PSW-MMS Explosion Proof Factory Sealed 3-Position Selector Switch is suitable for
preventing the ignition of external, flammable atmospheres in hazardous locations. This unit features the following
classified ratings: Class I, Division 1 & 2 (Groups C, D); Class II, Division 1 (Groups E, F, G); Class II Division 2
Groups F & G and Class III. The explosion proof switch comes with a 600V AC voltage rating and a weatherproof
build. When purchasing this product, please choose between 1/2" or 3/4" NPT hub sizes and feed thru/dead end
options.
WARNING: To avoid risk of explosion, all flat machined surfaces must be kept clean and free from scratches,
dents, debris, paint, and corrosion. The flat machined surfaces are explosion proof joints, and must be clean and
undamaged on both the enclosure and cover.
1. Do not use this equipment other than the intended use as specified on the equipment nameplate.
2. Turn OFF the supplying circuit before beginning installation or performing any maintenance.
3. Service should be performed by qualified service personnel.
4. All installations must comply with the applicable local and/or National Electrical Code. (Note: In the
orientation of the enclosure (box & cover), the “TOP” is considered to be at the location of the cast-in part
numbers.)
INSTALLATION
1. The surfaces of the flat ground joint are precision machined to insure an explosion proof joint and must
be protected from scratches or damage during installation.
2. When switch is mounted in the enclosure, it must be mounted to agree with cover indication of operation.
That is, when the cover indicates ON, the switch must be in the ON condition.
3. Before the cover is installed, the flat ground joint surface must be thoroughly wiped clean of any dirt, grit, or
other foreign substances and a light thin coating of lubricant placed on the joint to prevent possible
corrosion.
The joint between the box and the cover has been made accurately to .0015” to prevent the passage of
this accuracy is destroyed.
4. ALL cover screws must be installed with at least five full threads engaged and must be securely tightened.
All cover openings must be closed with a suitable cover.
5. Gaskets must not be added to these devices. Only gaskets designed for and permanently installed
in these devices may be used.
6. In accordance with the hazardous location information specifying Class and Group listing marked on the
device, sealing fittings must be added that will comply with requirements in the latest issue of the Canadian
Electrical Code or National Electrical Code and any special requirements that are stated in the instruction
sheet with the enclosure.
MAINTENANCE
Before removing the cover from any such device for inspection or maintenance, the power supply circuit must be
OFF.
WARNING: To prevent risk of explosion, hammers and prying tools must not be used to remove covers off
enclosures. Damage to the explosion proof flat machined surfaces on cover and enclosure may result. Handle
covers carefully. Do not place them on surfaces that might damage or scratch the flat machined surfaces.
Before replacing the cover, after it has once been removed, the flat ground joint surfaces must be cleaned
as described in step 3 under installation.
WARNING: To prevent risk of explosion, replace devices if the flat machined surface is damaged, scratched,
dented, or corroded. Field rework of flat machined surfaces is not possible.
