Stay online in a power cut in Ireland

Power the whole connection

The ONT is the powered box where fibre enters your home. Include it, the router and any essential network equipment in your load measurement. ComReg recommends battery backup for the router and modem where the upstream network remains powered.[1]

Worked example: assume a measured router load of 12W and ONT load of 6W: 12 + 6 = 18W. These are example inputs, not typical ratings. With an assumed power factor of 0.6, the AC load is 18 ÷ 0.6 = 30VA. Both the UPS watt and VA limits must exceed the connected load.[3]

VA describes output capacity, not hours of battery life. For energy, use watts × hours. Assuming 80% of labelled battery energy reaches the equipment:[3]

These are planning figures, not a UPS runtime promise. Check the manufacturer’s runtime curve at 18W, low-load shutdown behaviour and battery condition. Add laptop and backup-router demand separately. A large VA number can still accompany a small battery.[3]

Battery power keeps your equipment running, but cannot repair a failed broadband network or mobile mast.[1][2]

Would a 12V mini UPS do?

A DC mini UPS supplies compatible equipment directly. Match voltage, polarity, connector and current capacity to each device’s requirements. Do not assume both boxes take 12V. Manufacturer documentation shows selectable-voltage units and their connection requirements.[4]

Check whether it has enough correctly rated outputs for both boxes. Do not improvise a splitter. Ask for battery capacity in Wh: an illustrative 10,000mAh battery rated at 3.7V stores 10Ah × 3.7V = 37Wh, not 120Wh. At 18W and assumed 80% delivery, that is only 37 × 0.8 ÷ 18 = 1.6 hours.[3]

Add automatic mobile failover

Choose a 4G/5G router explicitly supporting Ethernet WAN plus cellular backup and automatic return to the main connection. A SIM slot alone does not establish that feature. Manufacturer guidance shows model-specific failover, with detection sometimes taking about a minute.[5]

Power the backup router too. Practise disconnecting the Ethernet WAN cable, then reconnecting it. Check your work VPN, calls and authentication during the change; do not assume a meeting survives it. Save essential documents offline and agree a fallback with your employer.

Check SIM permission before price

Prices need checking. A phone offer is not permission to use the SIM in a fixed router or for work. GoMo’s terms restrict business use, Tesco’s phone terms restrict dedicated-router use, and Clear’s speed terms need checking. Confirm router permission with the operator. Check an explicit broadband product such as Three’s prepaid broadband, and test reception before relying on it.[6][7][8][9][12]

For occasional backup, a supported phone hotspot can share a connection. Keep the phone charged. Check renewal, dormancy and allowance expiry with the provider; an expired allowance cannot provide automatic failover.[10][14]

Masts have limits

ComReg’s 2022 resilience study reported radio-access battery backup ranging from ten minutes to eight hours. That is historical evidence of variation, not today’s guarantee for your mast. Operators have since committed to additional battery and generator capacity.[2][15] Keep a charged phone, power bank and battery radio as the official checklist advises.[16]

Starlink as standby in Ireland

Check Starlink’s Irish plans for current availability, equipment, delivery and fees. Offers depend on address and account eligibility. Prices need checking.[17]

Standby is available for eligible Irish plans, providing up to 500kbps for messaging and account access. It is not a video-meeting plan. Promotional/rental exclusions apply; V5 hardware is excluded, and pausing does not reserve residential capacity. The public Irish page did not expose a euro Standby fee, so we cannot verify one. Check the account’s actual offer before buying.[18]

Starlink’s help centre lists Mini average AC draw at 20 to 40W, including its router, supply and cables. Four hours therefore needs 80 to 160Wh before backup-battery losses. Standard 4-family equipment averages 75 to 100W.[19] You still need a suitable sky view and a working Starlink service; this is another route online, not guaranteed connectivity.[17]