Electrical events that affect security equipment
Mains power is not perfectly steady. Equipment can experience several kinds of disturbance:
- Surges and spikes. Brief jumps in voltage, sometimes from the utility, sometimes from large appliances switching on and off nearby, and sometimes from lightning activity.
- Sags and brownouts. Voltage dips below normal for a short or longer time.
- Outages. Power is lost completely, briefly or for hours.
- Flicker. Rapid, short interruptions that can restart electronics even if the lights barely seem to change.
Security equipment is sensitive to some of these. A recorder that loses power while writing to its drives can corrupt data. A router that restarts at the wrong moment can drop the connection to a monitoring center. A camera that reboots repeatedly may miss events.
Surge protectors
A surge protector, often built into a power strip, diverts or limits excess voltage before it reaches the connected devices. Key points:
- It does not provide any power during an outage.
- Protection wears out. Many units absorb a limited amount of energy over their lifetime, and some have an indicator light that shows whether the protection is still active. Check the manual and replace units that show a fault or are very old.
- Quality varies. Ratings and certifications on the label are a better guide than price or marketing words.
- Connections matter. Data lines such as coax, telephone and network cables can also carry surges into equipment. Some protectors include ports for them.
No surge protector can promise to stop damage from a nearby direct lightning strike. Whole-building protection installed at the electrical panel is another option, and a licensed electrician is the right person to discuss it and to carry out the work. Rules and requirements differ by place.
Uninterruptible power supplies
An uninterruptible power supply, usually called a UPS, contains a battery and circuitry that takes over when mains power fails. Most small units also provide some surge protection and voltage regulation, though the amount differs between models.
Common types include:
- Standby units. Power passes through from the wall until a problem is detected, then the battery takes over after a very short switchover. These are common and inexpensive.
- Line-interactive units. They can adjust for small sags and rises without using the battery, which can be helpful where voltage is unstable.
- Online or double-conversion units. They continually run the load from the battery circuit. They offer the cleanest output but cost more and often run warmer and louder, so they are less common for home use.
What to put on a UPS
Think about what you actually need running during an outage.
- Network equipment. The modem and router are often the most useful items to protect. Without them, an internet-reporting panel or cloud-connected camera cannot reach the outside world.
- Recorders. A UPS gives a recorder time to continue recording or shut down cleanly instead of risking damage to its drives. This is relevant to local recorders in particular.
- Power over Ethernet switches. Backing up the switch can keep every connected camera alive; see power over ethernet.
- The panel’s transformer. Most panels already have a backup battery, so they may not need a UPS, but check the manual before adding anything.
Heavy loads such as laser printers, heaters and large monitors should not share a UPS with security equipment, because they eat capacity quickly.
Sizing the unit
UPS capacity is usually rated in volt-amperes and in watts. Add up the wattage of the devices you plan to connect, using the labels or specification sheets. Choose a unit whose watt rating comfortably exceeds the total, and then look at the manufacturer’s runtime chart for your load.
Here is a hypothetical example, purely for illustration. A router at 12 watts, a modem at 8 watts and a small recorder at 30 watts total 12 + 8 + 30 = 50 watts. A unit rated well above 50 watts would handle the load, and its runtime would depend on its battery capacity and the chart provided. Real numbers differ for each device.
Runtime shrinks as the battery ages. UPS batteries commonly need replacement every few years, and the unit usually reports when it needs service. A power outage then becomes a test you did not plan. It is better to follow the replacement habits suggested for backup batteries and check the UPS during regular maintenance.
Setting expectations
A UPS typically buys minutes to a few hours, not days. It reduces the chance of damage and gives time for short outages to pass, but it does not guarantee that a system keeps working. For a clearer picture of how each device behaves, read about what happens to a system during a power outage, and always follow the manuals and local electrical rules.