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Installation and Operations Guide

ACM-VLX/VLX/EXP/AXM

ungrounded side of the 24 V relays or other 24 VAC loads. See Figure 13 on

page 17 for a wiring diagram.

Cable Use 18 AWG cable for BO connections in most applications.

Providing isolated BO power BOs on the EXP/AXM require a power supply

separate from the EXP/AXM or VLX unit power supply. This isolates the

switched-load BO power from the EXP/AXM/VLX unit operating power, which

helps to prevent interference and electrical feedback noise from the switched

outputs affecting EXP/AXM operation.

Each EXP/AXM BO can deliver a maximum of 12 VA (24 VAC @ 0.5A). Each

EXP/AXM that supports BOs has a “BO MAX. LOAD” listed on the cover,

which indicates the maximum consumption in VA when all BOs are energized.

Always use this BO MAX. LOAD figure to determine the size and number of

transformers required to power BO loads. Even if all BOs are not currently used,

this ensures that the transformer(s) will not need to be exchanged to

accommodate future additions.

Any number of BOs can share a transformer, as long as the transformer is

adequately sized. See “Transformer sizing” on page 28.

A fast fuse is recommended on the hot leg of the 24 VAC BO power circuit to

prevent equipment damage from a shorted or faulty relay, a failed damper

actuator, a failed transformer, or other wiring or system faults. Size the fuse at

125% of the sum of all loads powered by the transformer.

Table 6 EXP/AXM BO te rminals

Te rminal labe l De s c ription

HOT <A|B|C|D> Use to terminate the hot leg of the 24 VAC circuit. This

terminal has switched, software-controlled, onboard

connections to the BO n terminals adjacent to it. For

transformer sharing between BO banks, jumper HOT

terminals together with 18 AWG wire. See Figure 13 on

page 17. DO NOT CONNECT THIS TERMINAL TO

GROUND OR EQUIPMENT DAMAGE WILL

RESULT.

BO n Use to connect to the ungrounded side of the 24 V relay

or other 24 VAC load. DO NOT CONNECT THIS

TERMINAL TO GROUND AND MAINTAIN

POLARITY FOR ALL CONNECTED LOADS OR

EQUIPMENT DAMAGE WILL RESULT.

Honeywell ALERTON ACM-AXM User Manual

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