Advanced MxPro 5: Common faults and how to clear them

Introduction to the MxPro 5

The Advanced MxPro 5 is one of the most widely deployed fire alarm panels in the UK commercial market. It's a flexible, networkable addressable panel, made in versions for different loop devices: the 5000 Series for Apollo (Discovery, Explorer, XP95 and Series 90) and Hochiki ESP, the 5000V for Advanced's own AV devices and the 5000N for Nittan Evolution (MxPro 5 Operating Manual, section 1.3).

Because of its flexibility, it's also a panel that generates a distinctive set of fault conditions — some specific to its architecture, some common to addressable systems in general. This guide covers the faults you're most likely to encounter on site, and the diagnostic approach for each.

Network Faults

The MxPro 5 is designed to operate as part of a networked system, and network faults are among the most disruptive issues you'll encounter. They can take entire zones or panels offline.

Symptoms

• Panel displaying "Network Fault" or "Node Fault"
• Other panels on the network showing as offline from the affected panel's perspective
• Devices on remote panels appearing as faults
• Network status LED showing fault condition

Probable causes

1. Network cable break — The most common cause. A break between nodes stops communication with the nodes beyond it; how much of the network that affects depends on how the network was designed and wired, which the site's network drawings and Advanced's installation manual (680-165) describe.
2. Faulty network card or module — The network interface card in the panel can fail, presenting as an inability to communicate even when the cable is intact.
3. Incorrect network addressing — If a panel has been configured with a duplicate network address (common after replacement or reconfiguration), the network will fault.
4. Network wiring or termination not as designed — check the network cabling and its terminations against the network section of the installation manual (680-165) for that installation.

Diagnostic approach

First, establish which node or nodes are reporting faults and which are unreachable. The MxPro 5's network diagnostics (View > Network) show the communication status of the nodes.

If a single node is unreachable, check the cable between the last communicating node and the unreachable node. If multiple nodes are unreachable, the fault is likely upstream of all of them.

Check the physical network connections at each panel: network card seating, cable terminations, and termination resistor placement. The panel's View > Network screen gives network diagnostics, and Network Hardware shows the circuits of the other panels and nodes on the network (Operating Manual, sections 3.9.7.3 and 3.9.9).

Loop Faults

Ground/Earth Faults

Symptoms: Panel showing "Earth Fault" or "Ground Fault" on a specific loop.

A ground fault means one of the loop conductors has a path to earth, usually through damaged cable insulation. The MxPro 5 actively monitors loop insulation and will generate a fault as soon as it detects this condition.

Diagnostic approach:

1. Note the loop number
2. Disconnect the loop at the panel — if the fault clears, the fault is in the field wiring or a device
3. Use a megohmmeter to measure insulation resistance between each loop conductor and earth. Caution: remove the loop devices (or isolate the section) first, or confirm the test voltage the device manufacturer allows; 250–500 V applied with devices fitted can damage them. Compare the reading with the commissioning record and with the other sections of the loop: the section reading far lower than the rest is where the fault is. Take any pass value from the current BS 5839-1 and the commissioning documentation rather than a rule of thumb, and note that the panel can report an earth fault at a resistance a megohmmeter would still call acceptable.
4. Section the loop at accessible junction points to narrow down which section the fault is in (short-circuit isolators do not operate on earth leakage)
5. Walk the route inspecting cable — look for damage, pinch points, cable touching metalwork

Common locations: Cable trays where cable has been bent sharply, entries to trunking or conduit, device bases where a cable core has been overtightened against the panel earth.

Short Circuit Faults

Symptoms: "Loop Short Circuit" fault, possibly with a section of devices going offline.

Where the loop has short-circuit isolators (EN 54-17), a short should be contained to the section between the isolators either side of it, and the devices beyond it on that side drop out.

Diagnostic approach:

1. Identify the isolated section from the panel display
2. Disconnect devices in that section one at a time to identify the device or cable causing the short
3. Check device bases — a cracked base or a foreign object inside the base can cause a short
4. Check cable condition in the isolated section

Communication Loss Faults

Symptoms: Specific devices showing as "Communication Lost" or offline, but loop otherwise operational.

This indicates the panel can't communicate with specific devices, even though the loop is generally intact. Common causes:

• Device removed from base without shorting plug
• Failed device (detector head failure)
• Addressing conflict (duplicate addresses — will cause both devices with the same address to disappear)
• Device outside the supported address range for this loop type

PSU (Power Supply) Faults

Mains Supply Fault

Symptoms: "Mains Fault" displayed on panel.

The panel has lost its mains supply. Check:

• MCB or fuse feeding the panel hasn't tripped
• Mains supply present at the panel's mains input terminals
• Mains wiring connections at the panel haven't come loose

Battery Fault

Symptoms: "Battery Fault" or "Battery Low"

The panel's standby batteries are below the minimum voltage threshold, or the batteries have failed. The MxPro 5 monitors battery health and will alert well before batteries reach a state where they'd fail to provide the required standby duration.

Check:

• Battery voltage with a multimeter (typically 2 × 12V sealed lead-acid). A battery showing significantly below 12V at rest is likely failed.
• Battery age — sealed lead-acid batteries used in fire alarm panels should be replaced typically every 4 years, depending on usage and environment.
• Charger circuit — if both batteries show low voltage simultaneously, the charger may have failed.

Charger Fault

Separate from battery fault — indicates a problem with the charging circuit. Requires investigation of the PSU board.

Accessing Fault Information on the MxPro 5

The MxPro 5 provides detailed fault logging and status screens:

• Event log: View > Log > Event Log (Operating Manual, section 3.9.8.1). Each entry shows time, date, panel, loop and address, zone, the event and the device's analogue value.
• Network: View > Network (section 3.9.9), and Network Hardware (section 3.9.7.3) for the other panels' circuits.

When attending a fault, always check the event log. The fault history will often show a pattern — repeated fault/restore cycles before the current fault — that helps identify intermittent issues before they become persistent faults.

Documentation

Per BS 5839-1, all faults, investigations, and remedial work must be documented in the system log book. For MxPro 5 systems, include:

• Fault type and panel address
• Date and time attended
• Probable cause identified
• Remedial action taken
• Confirmation of system restoration