CTU Installation Tips and Tricks

Last Week

We gave you a general overview of the CTU—our purpose-built monitoring hardware—and what to think about when choosing an installation location. If you missed it, you can catch up here: CTU Installation Options.

This Week: CTU Installation Tips and Tricks

A smooth CTU installation can save you time (and a few headaches). While the process is straightforward, there are some common issues we see again and again. This week we’re sharing our top tips, the most frequent installation mistakes, and a couple of hidden features you may not know about.

Top 5 Installation Issues We See

Here are the 5 most common installation issues our support team encounters.

1. SGD addresses not set correctly
The CTU polls each connected SGD in sequence to check the status of the fire alarm system. It does this by sending a message from the configured port and waiting for a response from the SGD at the assigned address. If the address on a multi-droppable SGD is set incorrectly—or if it’s connected to the wrong CTU port—the two devices won’t be able to communicate.

2. Loom Installed the wrong way around
This issue is easy to run into on some panels and applies only to in-panel installations. If the loom between the CTU and the panel is connected the wrong way around, the CTU won’t be able to read the panel’s status correctly, and the panel will often flag a “Defect.” To avoid this, check the installation guide carefully, ensure the loom isn’t twisted, and confirm it’s plugged into the correct port. One of the loom wires is marked to help you align it the right way—use this as your guide.

3. SGD not enabled via panel links or programming
Some fire alarm panels require programming or a jumper to be placed in the correct position on the motherboard to enable the SGD interface. Without this, the SGD won’t be activated and won’t be able to read the panel’s status. If you notice the SGD showing a different state than the panel, this should be the first thing to check.

In addition, some CTUs require a jumper to activate the second SGD port. These jumpers are normally configured correctly before the CTU is dispatched, but if they have been removed for any reason, it can cause issues. Always refer to the installation instructions to confirm jumper placement.

In both cases, the fix is usually straightforward. If you’re unsure, our support team is happy to help you diagnose and resolve any problems.

4. Aerial Installation Issues
Two common aerial installation mistakes:

• Aerial installed horizontally - The aerial transmits in a specific pattern and must be vertical to communicate effectively with the cellular network. Laying it flat or resting it on top of the box will result in poor signal, or it may not work at all. Make sure the aerial is vertical.
• Aerial installed inside metal box - Installing the aerial inside the fire alarm panel or CTU enclosure can sometimes work with the door open, but once closed, the signal will drop dramatically—or fail completely. Always mount the aerial outside the metal enclosure for reliable communication.

5. Battery vs SuperCap confusion
The CTU is designed to use either a battery or a SuperCap as its backup power supply—but never both at the same time. The SuperCap connector has a detection pin, which the CTU uses to recognize when a SuperCap is connected. If both a battery and SuperCap are plugged in, the battery can be overcharged and potentially damaged. Our support team will usually catch this during commissioning, but the rule is simple: use either a battery or a SuperCap, never both.

Sometimes we see batteries connected to the SuperCap port, or vice versa. This won’t harm the CTU, but it will leave it without an effective backup. Always double-check which port you’re using, and avoid modifying connectors to make them fit. When in doubt, give our support team a quick call—they’ll help you get it right.

Installation Resources

Every CTU ships with an installation guide—but we know those sometimes get left behind in the van or misplaced on-site. Don’t worry: we keep digital copies of all guides here: Installation Guides. It’s always worth having the latest version to hand before starting the install.

Support When You Need It

If you’re unsure where to start or run into something unexpected during installation, give our support team a call. They’ll be happy to help and answer your questions. A quick call upfront can often save time later during CTU commissioning.

Did You Know?

• Extra monitoring inputs - Each CTU can support up to 4 additional dry contact inputs (depending on installation type). These can be connected to pumps, detectors, generators, freezer alarms—or even vape sensors. We’ll dive deeper into how these inputs work and messaging options in a future article.
• Support for up to 8 SGDs - For in-box installs, the CTU can handle up to 8 SGDs. While we don’t recommend this approach for new installations (for the reasons we mentioned last week), it’s useful to know the capability is there.

Coming Next Week

We’ll be taking a closer look at messaging options, including:

• The different message formats and strategies we support
• How to temporarily pause messaging
• How to subscribe to all messages for a site for a set period, even if you don’t normally receive them