UPS Sizing & Runtime Guide
The right UPS size comes from your real load and required runtime, not a round-number guess.
How We Actually Size a UPS
Two numbers drive UPS sizing: your real critical load (measured, not estimated from equipment nameplates alone, which usually overstate actual draw) and how long that load needs to run on battery before either mains returns or a generator takes over. Undersizing either one is the common failure mode — a UPS that trips under load it should have handled, or a battery bank that runs out three minutes before the generator was supposed to start.
We start every sizing exercise with a load assessment rather than a capacity recommendation, then add headroom for future growth and account for battery derating in hot environments, since VRLA and lithium-ion batteries both lose usable capacity as ambient temperature rises above their rated range.
The Sizing Process
- Real load measurement, not nameplate wattage alone
- Required runtime, set against your generator start time or acceptable outage window
- Headroom for future load growth, so the UPS isn't undersized within a year
- Battery derating for ambient temperature, particularly relevant in Gulf climate battery rooms
- Topology recommendation (online, line-interactive or standby) based on how sensitive the load actually is
Frequently Asked Questions
Why would nameplate wattage give me the wrong UPS size?
Equipment nameplates list maximum rated draw, which is often well above what the equipment actually pulls in normal operation. Sizing off nameplate figures alone tends to produce an oversized, more expensive UPS — or, if someone under-corrects for it, an undersized one. A real load measurement gives a much more accurate number.
How much extra runtime should I plan for beyond my minimum requirement?
It depends on how confident you are in your generator's start time and how disruptive a shortfall would be. We typically build in headroom rather than sizing to the exact minimum, since batteries also lose some capacity over their service life — sizing to the bare minimum on day one means undersized runtime well before the battery's rated end of life.
UPS brands we supply, install and maintain
We work with the UPS systems commonly installed in Saudi Arabia and the GCC, so one team can supply, install and maintain the units on your site, including mixed-brand installations.
- Schneider Electric (APC)
- Eaton
- Vertiv (Liebert)
- Riello UPS
- Socomec
- Legrand
- ABB
- Huawei
- Delta Electronics
- Kehua
- Borri
- Gamatronic
- AEG Power Solutions
- Mitsubishi Electric
- Toshiba
- Fuji Electric
- Salicru
- INFORM
- KSTAR
- CyberPower
Brand names are trademarks of their respective owners. Black Arrow is an independent supplier and service provider.
Maintenance and support after handover
Our work does not end at commissioning. We keep your systems running with a maintenance plan built around your site.
1, 2 or 3-year maintenance contracts
Planned preventive maintenance visits, inspection and test reports, and recommendations, on a contract length that suits your site.
Emergency visits
Emergency call-outs are part of the maintenance contract and are handled with priority according to the criticality of your site.
One team for every system
We maintain every system we supply and install, and we can take over the maintenance of existing systems on your site.
Visit frequency, emergency arrangements and spare parts are agreed with each client based on the site and the systems covered.
Request a quote or site survey
Tell us about your site and what you need. An engineer will review your request and contact you to discuss it.
- Supply, installation and commissioning
- Maintenance contracts and emergency visits
- Site surveys and technical assessments