Types And Maximum Allowable Length Of Cables - Mitsubishi Electric City Multi PQHY-P72 Service Handbook

II Restrictions

[1] Types and Maximum allowable Length of Cables

1. Wiring work
(1) Notes
1) Have all electrical work performed by an authorized electrician according to the local regulations and instructions
in this manual.
2) Install the control cable at least 5cm[1-31/32"] away from the power supply cable to avoid noise interference. (Do
not put the control cable and power supply cable in the same conduit tube.)
3) Provide class-D grounding on the outdoor (heat source) unit.
4) Run the cable from the electric box of the indoor or outdoor (heat source) unit in such way that the box is accessible
for servicing.
5) Do not connect the terminal block for transmission line to supply voltage of 208V or 230V. Doing so will damage
the electronic components on the terminal block.
6) Use 2-core shielded cables as control cables. (Marked with OK in the figure below) Use a separate 2-core control
cable for each refrigerant system. Do not use a single multiple-core cable to connect indoor units that belong to
different refrigerant systems. The use of a multiple-core cable may result in signal transmission errors and malfunc-
tions. (Marked with NO in the figure below)
Heat source unit
OK
TB3
TB7
2-core shielded cable
TB3
TB7
2-core shielded cable
TB3:Terminal block for transmission line connection
(2) Control wiring
Different types of control wiring are used for different systems.
Refer to section "[4] An Example of a System to which an MA Remote Controller is connected - [6] An Example of a Sys-
tem to which both MA Remote Controller and M-NET Remote Controller are connected" before performing wiring work.

[Types and maximum allowable length of cables]

Control lines are categorized into 2 types: transmission line and remote controller line. Use the appropriate type of cables
and observe the maximum allowable length specified for a given system. If a given system has a long transmission line
or if a noise source is located near the unit, place the unit away from the noise source to reduce noise interference.
1) M-NET transmission line
Facility
type
Type
Cable type
Number of
cores
Cable size
Maximum transmission
line distance between the
outdoor (heat source) unit
and the farthest indoor unit
Maximum transmission
line distance for central-
ized control and Indoor/
outdoor (heat source)
transmission line
(Maximum line distance
via outdoor (heat source)
unit)
Indoor unit
Remote Controller
TB7: Terminal block for transmission line for centralized control
Shielded cable CVVS, CPEVS, MVVS
Larger than 1.25mm
500 m [1640ft] max.
*The maximum overall line length from the power supply unit on the transmission lines for
centralized control to each outdoor (heat source) unit or to the system controller is 200m
[656ft] max.
- 17 -
Heat source unit
Indoor unit
NO
TB3
TB7
Multiple-core cable
TB3
TB7
All facility types
2-core cable
2
[AWG16]
200 m [656ft] max.
[ II Restrictions ]
Remote Controller