Engineering Documentation

Appendix A – Discontinued Products
Multi-Point Unit/Digital Point Unit (MPU/DPU)
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Wire Type Requirements
MPU and DPU Wire Type Requirements.
Circuit Type Class Wire Type (AWG) Distance Conduit Sharing
1
AC line power
(to field panel)
Power
No.12 to No.14,
No.12 THHN
Check local codes Check local codes
Digital Output 1 Check local codes Check local codes Check local codes
Digital Output 2 Check local codes Check local codes Check local codes
Digital Input
(MPU and DPU)
2 No.18 to No.22 TP 750 ft (230 m) Class 1 and 2
(check local codes)
Analog Input (MPU) Thermistors 2 No.18 to No.22 TP 100 ft (30.5 m) Class 1 and 2
(check local codes)
MPU Power Trunk 2
No.14 THHN OR
No.14 TP
180 ft (55 m)
2
Class 1 and 2
(check local codes)
1)
Conduit sharing rules were determined through EMI and shared conduit testing. These rules indicate wiring methods that have
no adverse affect on the proper operation of the equipment, but do not necessarily indicate compliance with local codes.
2)
Distances depend on transformer location. Install 100 VA transformers near the most convenient line voltage sources to
minimize line voltage wiring costs. Use one 100 VA transformer for every eight MPUs. (180 ft using 14 AWG wires is worst
case).
Power Source Requirements
The MPU can be powered in two ways:
● Individual transformer using a transformer rated for Class 2 service.
● Power trunk. For more information, see the section Power Trunk Guidelines
[➙ 64].
CAUTION
The phase of all devices on a power trunk must be identical.
Phase differences can destroy equipment. Any relays, EPs, or contactors sharing
power must be clamped with MOVs at their locations.
MPU/DPU Power Source Requirements.
Product Input Voltage Line Frequency Maximum Power
MPU 24 Vac 50/60 Hz 30 VA
DPU – 115V 115 Vac 50/60 Hz 50 VA
1
DPU – 230V 230 Vac 50/60 Hz 50 VA
1
1)
Service outlets are restricted to only continuously power network devices.