Installation 
4/07  UDC2500 Universal Digital Controller Product Manual  17 
2.6 Wiring 
2.6.1 Electrical Considerations 
Line voltage wiring 
This controller is considered “rack and panel mounted equipment” per EN61010-1, 
Safety Requirements for Electrical Equipment for Measurement, Control, and Laboratory 
Use, Part 1: General Requirements. Conformity with 72/23/EEC, the Low Voltage 
Directive requires the user to provide adequate protection against a shock hazard. The 
user shall install this controller in an enclosure that limits OPERATOR access to the rear 
terminals. 
Mains Power Supply 
This equipment is suitable for connection to 90 to 264 Vac or to 24 Vac/dc 50/60 Hz, 
power supply mains. It is the user’s responsibility to provide a switch and non-time delay 
(North America), quick-acting, high breaking capacity, Type F (Europe), 1/2A, 250V 
fuse(s), or circuit-breaker for 90-264 Vac applications; or 1 A, 125 V fuse or circuit 
breaker for 24 Vac/dc applications, as part of the installation. The switch or circuit-
breaker shall be located in close proximity to the controller, within easy reach of the 
OPERATOR. The switch or circuit-breaker shall be marked as the disconnecting device 
for the controller. 
 
 
CAUTION
 
  Applying 90-264 Vac to an instrument rated for 24 Vac/dc will severely 
damage the instrument and is a fire and smoke hazard. 
 
When applying power to multiple instruments, make certain that sufficient current is 
supplied.  Otherwise, the instruments may not start up normally due to the voltage drop 
caused by the in-rush current. 
Controller Grounding 
PROTECTIVE BONDING (grounding) of this controller and the enclosure in which it is 
installed shall be in accordance with National and Local electrical codes. To minimize 
electrical noise and transients that may adversely affect the system, supplementary 
bonding of the controller enclosure to a local ground, using a No. 12 (4 mm
2
) copper 
conductor, is recommended. 
Control/Alarm Circuit Wiring 
The insulation of wires connected to the Control/Alarm terminals shall be rated for the 
highest voltage involved. Extra Low Voltage (ELV) wiring (input, current output, and 
low voltage Control/Alarm circuits) shall be separated from HAZARDOUS LIVE (>30 
Vac, 42.4 Vpeak, or 60 Vdc) wiring per Permissible Wiring Bundling, Table 2-5. 
Electrical Noise Precautions 
Electrical noise is composed of unabated electrical signals which produce undesirable 
effects in measurements and control circuits.