The best Eaton UPS units, compared.
Top pick: Eaton 5E900UI 900 VA Best value: Eaton 5E900UI 900 VA – Display award at about £118.57 for 900 VA and 480 W, score 90 from 125 reviews. More watts than the 3S700B at a lower shelf price, on IEC outlets, with the review sample outside the UK. Updated 22.10.2026.
An Eaton UPS is either a 36 W DC battery one low-voltage device or a 230 V tower that bridges a cut for minutes at a load. You are choosing among seven Eaton listings on amazon.co.uk, with prices. Judge them by watts, by how many sockets are battery-backed, and by whether the lead is BS 1363. On the 5S and 5E is the brownout feature the offline 3S and 3P do not claim. Add the load up in the [Eaton UPS sizing guide](/hub/electrical-equipment/eaton-ups/sub/eaton-ups-how-to-size). United Kingdom mains are 230 V at 50. A lead is a buying defect when the kit is meant for a BS 1363 socket. Regulation 35 of the (Safety) Regulations 2016 requires a correctly fitted BS 1363 plug, or a compliant non-UK plug with a conversion plug and a BS 1362 fuse, for that domestic use.
An Eaton UPS is either a 36 W DC battery one low-voltage device or a 230 V tower that bridges a cut for minutes at a load. You are choosing among seven Eaton listings on amazon.co.uk, with prices.
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Personal buying guide
Question 1 of 2
What does the load plug into?
The Eaton 5E900UI is a 900 VA line-interactive tower rated at 480 W, with four IEC outlets and a 24-minute runtime field on the listing. At £118.57 it is the lower shelf price against the 3S700B, with more watts, though the 4.5 score comes from 125 reviews sampled outside the United Kingdom. Owners describe easy setup and shutdown with Synology, QNAP, and Network UPS Tools. Several say the mains lead was missing and that only two IEC output cables arrived. One French review calls the unit warm, one South African unit was dead after a day of charging, and a UAE review reported a burning-plastic smell with no load. The plug attribute says no plug, and the connector type is IEC 320, so this listing is not selling BS 1363 outlets. The output attribute copies 900 V from the VA figure, which is not a usable mains voltage.
Pros
Cons
Best for: You already use IEC leads for a NAS or small server and want about 480 W in a line-interactive Eaton.
Less suitable: Every load has a BS 1363 plug, or you want to treat the 125 reviews as British owners.
Specifications
Common questions
Are the outlets UK 13 A sockets?
The connector type is IEC 320. The listing does not say BS 1363 outlets.
What runtime does the listing give?
Both the runtime field and the battery-life field say 24 minutes.
Where are the reviews from?
The score is 4.5 from 125 reviews. The review text in the saved listing is from outside the United Kingdom.
The Eaton 3S700B is a 700 VA offline tower rated at 420 W, and UK reviewers use it to ride spikes on a home server or to shut a gaming PC down before the battery dies. One owner kept a Synology NAS up for about 10 minutes, then let the shutdown finish. The listing gives four of the eight BS outlets battery backup, and reviewers notice that the other four are surge-only. HID USB is claimed, though one UK owner said the shutdown software failed to load nine times out of ten. The star line is 4.5 from 58 reviews, and the sample titles are largely from the United Kingdom. The plug attribute says Type B, which conflicts with the BS-outlet title, so you should check the lead in the box. One UK review reports a unit dead on arrival, and the listing does not claim automatic voltage regulation.
Pros
Cons
Best for: You want British sockets on an offline Eaton for a PC, NAS, or router, and your supply does not need brownout correction.
Less suitable: You need AVR, more than four battery-backed sockets, or a lead you do not have to check against a Type B attribute.
Specifications
Common questions
Do all eight sockets stay on in a power cut?
The listing says four BS outlets have battery backup and surge protection, and four are surge-only.
Does the listing claim automatic voltage regulation?
No. The item type name is off-line. AVR is not in the bullets.
What plug does the attribute table name?
The table says Type B, a North American 3-pin plug. That conflicts with the BS-outlet title, so check the lead in the box.
The Eaton 3P700I is a fanless offline Ellipse rated 700 VA and 420 W, and the listing says the models run with no fan and under 25 dB. The bullets give four IEC C13 outlets, three with battery backup and one surge-only, while the title also mentions four extra surge-only outlets, so the socket count is not clean. One United Kingdom review uses it on an ONT, a router, and a cordless-phone base, and the reviewer expects about an hour on that small load. The star line is 4.5 from only two reviews, so that praise is a single account. The plug attribute is Type C, not BS 1363, and the outlets are IEC. The warranty field is three years on electronics and two years on the batteries, with a replaceable battery claimed. Item weight is 3.7 kg and a bullet says 4.3 kg.
Pros
Cons
Best for: You want a quiet offline Eaton for a light IEC load and you accept a two-review sample.
Less suitable: You need BS 1363 outlets, AVR, or a review count you can lean on.
Specifications
Common questions
How many outlets have battery backup?
The bullets say four IEC C13 outlets, three with battery backup and one surge-only. The title also mentions four extra surge-only outlets.
Is there a fan?
The listing says the models operate with no fan.
Does the plug attribute say BS 1363?
No. The plug type field says Type C.
The Eaton 5E2200UI is the only unit in this set rated 2,200 VA and 1,200 W, with six IEC C13 outlets and a listing runtime of 52 minutes. At £376.32 it is the highest price here. The 3.8 score comes from 23 reviews, and the sample text is from outside the United Kingdom. One South African owner reported about 45 minutes on a Linux server with Network UPS Tools, while another complaint is a fan that spins up every 30 seconds to two minutes. Reviewers say the mains lead and the USB cable were not in the box, and that local plugs need adapters for the kettle-style outlets. A UAE review describes a unit that died after 13 months, outside a 12-month regional warranty. The plug attribute says no plug, the form field says rack, and two dimension sets appear on the listing.
Pros
Cons
Best for: Your load is near 1 kW, you already use IEC leads, and you have measured the shelf against the listing dimensions.
Less suitable: A home PC on BS 1363 plugs, or a buyer who needs the mains lead in the carton.
Specifications
Common questions
Does the listing include a mains lead?
The plug attribute says no plug. Reviews in the saved listing say the mains lead was not in the box.
What sockets are on the back?
The title says six IEC C13 sockets. A reviewer confirmed kettle-style outlets and no local mains sockets.
Is the cotton field a real material?
No. The saved listing also says 100 percent cotton and mahogany. Those fields are scrape noise. The colour field that matches a UPS is black.
The Eaton 3S Mini, model 3SM36B, is a 36 W DC battery for one low-voltage device, not a 230 V socket for a PC. UK reviewers use it to keep a BT modem, an ONT, or a VoIP line up through cuts, and some describe an easy fit that lasted more than one winter. The bullets offer 9, 12, 15, and 19 V with four barrel sizes, yet reviews say the box lacks a tip for some Asus routers and for the BT Smart Hub 2. The star line is 3.6 from 190 reviews, the largest count in this Eaton set, and the sample includes United Kingdom text. Battery failure around two years, including just after the warranty, comes up more than once, and one buyer saw one of three units drop its output immediately. The listing shows both 5 hours and 150 minutes as runtime fields, so those two figures cannot both be your answer. The plug attribute says no plug. Set the voltage to the label on the device before you connect it.
Pros
Cons
Best for: Your ONT or router uses a barrel that is in the box and draws well under 36 W.
Less suitable: You need to back up a PC, or your hub is a BT Smart Hub 2 or an Asus that needs a 4.0 x 1.35 mm tip.
Specifications
Common questions
Can this run a desktop PC?
No. It is a 36 W DC supply with barrel tips, not a 230 V AC outlet.
Will the tips fit every UK router?
UK reviews say the box lacks a tip for some Asus routers and for the BT Smart Hub 2.
What plug does the listing record?
The plug type field says no plug.
The Eaton 5S550IBS is the smallest line-interactive AC unit in this set, rated 550 VA and 330 W, and the bullets say automatic voltage regulation corrects fluctuations without using the batteries. Three of four IEC C13 outlets are battery-backed, and the fourth is surge-only. The title claims a BS input cord, while the plug attribute says Type E/F, so the lead in the box is not settled by the page alone. The star line is 3.5 from four reviews, and the only review text in the file is a short Italian note that the unit works. That is too thin to read as a UK verdict. Two IEC output cords and a USB cable are listed in the box, which helps a device that already speaks HID, but a British plug will not seat in a C13 socket. At £111.43 it is the cheapest AC Eaton here, and the trade is AVR plus a four-review sample.
Pros
Cons
Best for: You want AVR and a USB cable on a light workstation, and you already own IEC leads.
Less suitable: You want BS outlets on the UPS, or a review sample you can treat as UK owners.
Specifications
Common questions
Does this model correct brownouts without the battery?
The bullets say automatic voltage regulation corrects fluctuations without using the batteries.
Will a UK plug go straight into the outlets?
The outlets are IEC C13. The BS lead, where the bullet is right, is the input cord, not a BS socket on the UPS.
How many UK reviews are in the saved listing?
The score is 3.5 from 4 reviews. The only review text in the file is from Italy.
The Eaton 3P900UI is a fanless offline Ellipse rated 900 VA and 540 W, with four IEC C13 outlets and USB-A and USB-C charge ports claimed. At £156.30 it costs more than the 420 W and 480 W Eatons in this set, and the star line is 3.2 from five reviews. One UK owner kept a digital-voice landline up through two cuts, and another was content using it with a NAS. Other UK reports say the battery arrived discharged, past the packaging date, and that two units alarmed while they were on mains and were returned. Battery average life on the listing says 31 minutes, while the runtime field says 1 hour. The plug attribute is Type C. Three years on the electronics and two on the batteries are claimed, which does not clear a flat pack on day one.
Pros
Cons
Best for: You want a fanless 540 W offline Eaton on IEC leads and you can live with a five-review sample.
Less suitable: You want BS sockets, AVR, or a unit whose reviews do not start with a flat battery.
Specifications
Common questions
Why do the runtime fields disagree?
Battery average life says 31 minutes. The runtime field says 1 hour. Both are on the listing.
What did the UK reviews report?
One owner kept a digital-voice line up. Others reported a flat battery on arrival and units that alarmed on mains.
Is the plug a UK 13 A plug on the listing?
The plug type field says Type C.
Seven Eaton UPS listings on amazon.co.uk were scored from the saved display file. Shelf prices are the 19 October 2026 snapshot. There was no lab test. The published score is the amazon.co.uk star average times 20, so 4.5 is 90 and 3.2 is 64. Review volume is not inside that number. The top pick and the best value are the display awards: the 3S700B, whose title describes BS outlets, and the 5E900UI, at 480 W for about £118.57. Plug clashes, missing leads, and review origin stay in the assessment. They do not change the star score.
Amazon star line
70%The published score is the amazon.co.uk star average times 20. A 4.5 line is 90 and a 3.2 line is 64. Review volume is not inside that number, so 58 UK-heavy reviews and two reviews can share a score of 90.
Watts, sockets and the plug
20%Output type, rated watts, battery-backed outlets, and the plug or IEC lead are read from the listing and shown in the table. Those facts do not add points on top of the star line. The awards use them: BS outlets for the top pick, and more watts at a lower shelf price for best value.
Limits kept in the assessment
10%A Type B or Type C attribute against a BS title, a missing mains lead, a non-UK review sample, and a runtime field that disagrees with itself stay beside the product. Scores were not reduced again for those limits. Price is not inside the score.
Start with output type, then watts, then how many sockets stay alive in a cut, then the plug in the box. AVR and the origin of the reviews come after those. The notes below follow that order for these seven amazon.co.uk listings, priced on 19 October 2026. None of the scores is a runtime test.
An Eaton UPS in this set is one of two jobs. The 3SM36B, about £53.99 with 3.6 from 190 reviews, is a 36 W DC UPS with selectable 9/12/15/19 V barrels. Every other model is a 230 V AC UPS. They do not replace each other. United Kingdom mains are 230 V at 50 Hz. A Schuko lead is a buying defect when the kit is meant for a BS 1363 socket.
Eaton states 420 W on the 700 VA 3S models, a power factor of 0.6. The UK buying guide says to use watts, allow about 20% more VA than the load, and stay under about 80% of capacity. A 700 VA title is not a 700 W budget.
Surge-only outlets die in a blackout. On the 3S700B, four of the eight BS outlets are battery-backed and four are not. Count the battery sockets before you assign the router or the ONT.
The 5E900UI connector is IEC 320, not the BS part 5E900UB. The plug attribute says no plug, and several reviews say the mains lead was missing. A conflicting plug field is not a BS 1363 lead.
Separate the 36 W DC 3S Mini from every 230 V tower before you compare prices. Listing watts are 36, 330, 420, 480, 540, and 1,200. The 3S700B is 420 W with four battery-backed BS outlets out of eight. The 5S550IBS is 330 W with three battery-backed C13 outlets out of four. The 5E900UI is 480 W with four IEC outlets, and the listing does not split battery from surge. The 3P700I is 420 W and the 3P900UI is 540 W, both IEC, and the 3P700I title and bullets do not agree on extra surge sockets.
Offline on the 3S Gen2 means no AVR claim. The 3P Ellipse pair is also offline and fanless on the listing, with three years on the electronics and two years on the batteries. Line-interactive AVR is the 5S bullet, and the Eaton page gives a 175–275 V window. The 5E Gen2 datasheet lists 140–300 V without the battery and lists UKCA. The two 5E amazon.co.uk listings here do not state AVR in the attribute table, so do not treat the shelf page as the datasheet.
Three typical situations, each with a recommendation from this comparison.
You want BS outlets on an offline Eaton for a PC, NAS, or router, and the supply does not need brownout correction. The 3S700B is about £124.06, with four of eight BS outlets battery-backed. Check the lead against the Type B attribute.
The ONT sits away from the PC and the device draws well under 36 W on a barrel that is in the box. The 3S Mini is about £53.99. It is not a 230 V socket, and some Asus routers and the BT Smart Hub 2 need a tip the box lacks.
You already use IEC leads and want about 480 W in a line-interactive Eaton, with USB shutdown named in the title. The 5E900UI is about £118.57. The 125 reviews are not a British sample, and the mains lead was missing in several of them.
In this set of seven amazon.co.uk listings, the top pick is the Eaton 3S700B. It is about £124.06, with 4.5 from 58 reviews, and the title describes eight BS outlets, four of them battery-backed, at 700 VA and 420 W. The score is 4.5 times 20, which is 90. The plug attribute says Type B, which conflicts with that title, and automatic voltage regulation is not claimed. The best value is the Eaton 5E900UI at about £118.57, 900 VA and 480 W, also scoring 90 from 4.5 and 125 reviews. It lists more watts at a lower shelf price than the 3S700B, on IEC outlets rather than BS 1363 sockets. That review text is from outside the United Kingdom. The 3P700I also scores 90, from only two reviews. None of these scores is a lab test.
Eaton 5E900UI 900 VA
Display award at about £118.57 for 900 VA and 480 W, score 90 from 125 reviews. More watts than the 3S700B at a lower shelf price, on IEC outlets, with the review sample outside the UK.
Editorial
Peter F. is the editor for DIY & tools at productscompared.co.uk. Comparisons in this category are checked against amazon.co.uk listings, review evidence and public UK sources.
Guides on what to look for, how to use a product, and common mistakes.
Public sources from the research digest, last checked on 19 October 2026. Shelf prices and star lines are the amazon.co.uk figures in the display file.
Expert source (DIY & tools): Charlie White (Charlie DIYte) (external profile) – public expert commentary used as a research source, not as a contributor to our pages.
This page contains affiliate links to amazon.co.uk. If you buy through them, we may earn a commission at no extra cost to you. Prices, stars and review counts are from the UK listings checked on 19 October 2026. We did not lab-test these Eaton UPS units.
