Step 4: Installation of the EM3000 System
11
Doc 6001536, Rev C
GROUNDING THE 110 VAC POWER LINES
All high voltage grounding and wiring should comply with local, state, and federal regulations, as well
as conform to NEC standards. In general, use a third green wire ground with 110 VAC power runs.
Ground wire should be appropriately connected to source ground, as well as junction boxes, back-
boxes, and enclosures.
GROUNDING READER AND DOOR HARDWARE CABLES
Ground the shield/drain wires from readers, door strikes, door status sensors, and REXs at the earth
ground screw, located within the EMC cabinet (see Figure 6).
Procedure:
1.
All cables from readers, door strikes, door status sensors, and REXs must be properly earth
grounded to ensure stable operation. Use the “Open-ended grounding” technique. This
technique means to tape back, or isolate, one end of the shield drain wire and earth ground
the other. An example would be to tape back the shield at the reader side and to tie the
shield at the EMC side to earth ground (see Figure 10). Please be aware that operation is
affected by the amount of static present during certain times of the year.
2.
At the reader site, it is important to be aware of both the static generated from electrical
grounding from the data and reader cabling, as well as the user site. If at all possible, the
reader mounting plate should be attached to a grounded junction box or to another grounded
source, if the junction box is non-metallic. This alleviates the possible damage caused by
static electricity.
3.
If grounding locally is not possible, connect drain wires to provided ESD (Electro Static
Discharge) hardware at the unit site (enclosure) or to an earth-grounded conduit. As each
reader port is progressively farther away from the ESD hardware location, allow for enough
drain line to reach the ESD hardware on the EMC end of the cable. Allow enough strain relief
to avoid touching other circuitry or creating excessive tension.
GROUNDING THE RS-485 COMMUNICATIONS CONNECTION
The cable connecting the RS-485 converter (at the PC) to the EMC must have its shield/drain wire
grounded to the host PC (at case screw). The other end of the cable’s shield/drain wire must be
attached to the EMC board (at SHIELD). For more information, refer to
Converter (EMC to PC Communication)
on page 20.
