One 230 V device on Schuko
You already use 16 A Schuko connectors and you want a portable 230 V to 230 V box at 1.5 kVA continuous. The Watts Control unit is about £149.99. The intermittent duty is unstated, and it is not a BS 1363 plug.
Isolation transformer comparison 2026
The best isolation transformers, compared.
Top pick: Watts Control 1.5 kVA cased isolator – Only cased 230 V listing in this set: about £149.99, GRP case, 1.5 kVA continuous, 10 A trip, score 68 after Schuko connectors, no duty cycle and no reviews. Best value: SACVXOKD BK150VA 150 VA chassis – Lower price that still states 150 VA and 0.68 A: about £41.99, score 44 after no enclosure, no plug, no standard and a 220 V plate. Updated 22.10.2026.
Charlie White (Charlie DIYte)Expert source
An isolation transformer here is a mains unit with separate windings, usually 230 V to 230 V, so the output is galvanically separated from the supply. In the UK it is for one appliance or a repair bench, not a substitute for a 110 V site transformer. Judge a listing by the BS EN IEC 61558 part, a continuous rating that matches the load, and a connector that fits the socket you have. A floating secondary is still 230 V between its lines. Those checks are set out in the [isolation transformer buying guide](/hub/electrical-equipment/isolation-transformer/sub/isolation-transformer-buying-guide). The consumer object is a portable cased unit, usually 230 V to 230 V, with a lead, a socket and a trip. It is not a 110 V site transformer, and it is not a [mains isolation switch](/hub/electrical-equipment/mains-isolation-switch), which opens the supply rather than separating the windings. Chassis parts of 20 VA or 150 VA have no plug and no declared enclosure.
An isolation transformer here is a mains unit with separate windings, usually 230 V to 230 V, so the output is galvanically separated from the supply.
11 products checked · 51 hrs invested · +17,200 readers
3 of 3: Best isolation transformers compared
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7.0/10
4.6/10
2.8/10
∼ £150
∼ £42
∼ £22
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Personal buying guide
Which isolation transformer fits this job?
Question 1 of 2
What are you fitting?
The best isolation transformers in detail
Our view
The Watts Control WCPT3000/230/SCHUKO is the only cased unit in this amazon.co.uk set, listed at £149.99 with a GRP enclosure and a stated 230 V input and 230 V output. The rating line on the page is 1.5 kVA continuous and 3 kVA intermittent, plus a 10 A thermal-magnetic trip you reset by hand. At 230 V that 10 A trip is 2,300 VA, which sits between those two figures, and the listing never states the intermittent duty, so the 3 kVA in the title is not an all-day load. The connectors are a 16 A Schuko plug and two 16 A Schuko sockets, which do not fit a BS 1363 socket. The page claims BS EN 61558 and does not name a part, and amazon.co.uk shows no customer-review line. It is the top pick in this set only because it is the sole listing that states a case, a trip and sockets, and only if you already accept Schuko connectors.
Pros
- Only cased listing: GRP enclosure, 230 V to 230 V, a stated plug and two sockets
- 1.5 kVA continuous and 3 kVA intermittent printed, plus a 10 A hand-reset trip
- Manufacturer named as Watts Control Transformers LTD, model WCPT3000/230/SCHUKO
- BS EN 61558 is claimed, unlike the two chassis listings
Cons
- 16 A Schuko plug and sockets, not BS 1363
- No duty cycle for the 3 kVA intermittent rating
- Standard claimed without a part number
- No customer-review line on amazon.co.uk
Best for: A reader who already uses 16 A Schuko connectors and wants a portable 230 V to 230 V box at 1.5 kVA continuous, accepting that the intermittent duty is unstated.
Less suitable: A UK 13 A socket, a load that needs the 3 kVA figure all day, medical IT, or a 110 V building-site supply.
Specifications
- Model
- Watts Control 1.5 kVA cased isolator
- Brand
- Watts Control
- Price
- ∼£150
- Input voltage
- 230 V
- Output voltage
- 230 V
- Continuous rating
- 1500 VA
- Intermittent rating
- 3000 VA
- Input connector
- 16 A Schuko plug
- Output connector
- 2 x 16 A Schuko
- Overload protection
- 10 A trip, hand reset
- Enclosure
- GRP
- Standard claimed
- BS EN 61558
Common questions
What voltages does this isolation transformer list?
The listing states a single-phase supply, 230 V input and 230 V output, for electrical isolation of a standard European 230 V mains supply.
What load does the listing allow?
The listing states 1.5 kVA continuous and 3 kVA intermittent, plus a 10 A thermal-magnetic trip that can be reset by hand. It does not state the intermittent duty cycle.
Does the plug fit a UK 13 A socket?
The listing states a 16 A Schuko input plug and two 16 A Schuko output sockets. It does not state a BS 1363 plug or socket.
Our view
The SACVXOKD BK150VA is a chassis transformer listed at £41.99 as 150 VA, 220 V to 220 V, a 1:1 ratio and 0.68 A. The title names copper, and the page does not state a plug, a socket, an enclosure or a standard. The listing asks whether it has a thermal cut-off, and the page does not answer that. Amazon.co.uk shows no customer-review line, so there is no UK account of heat or a failed winding. At 0.68 A the part is a small instrument or control load, not a kettle or a mains drill. It is the best value here only as the lower price that still states a current you can compare with a load, if a competent person is building it into an enclosure, and the 220 V plate is not a 230 V claim.
Pros
- 150 VA, a 1:1 ratio and 0.68 A stated at £41.99
- Copper named in the title
- Lower shelf price than the only cased unit, with a current you can compare to a load
Cons
- No plug, socket, enclosure or standard
- 220 V plate, not a stated 230 V unit
- Thermal cut-off question unanswered
- No customer-review line on amazon.co.uk
Best for: A competent person fitting a stated 0.68 A, 220 V chassis part into their own enclosure for a load that stays inside 150 VA.
Less suitable: Anyone who wants a finished appliance, a UK 13 A plug, or a kettle, drill or other load above a fraction of an amp.
Specifications
- Model
- SACVXOKD BK150VA 150 VA chassis
- Brand
- SACVXOKD
- Price
- ∼£42
- Input voltage
- 220 V
- Output voltage
- 220 V
- Continuous rating
- 150 VA
Common questions
What power does this isolation transformer list?
The title states 150 VA, 220 V to 220 V, a 1:1 ratio, and 0.68 A. The current-rating field also states 0.68 amps.
Does the listing include a UK plug or a thermal cut-off?
No plug, socket, enclosure or standard is stated. The listing asks whether it has a thermal cut-off and does not answer that.
Is there a customer rating?
The amazon.co.uk listing has no customer-review line and no review text.
Our view
The FUNTLY listing, with DB-20VA in the title, is a 20 VA chassis transformer at £22.00, stated as 220 V to 220 V and 1:1, surface mount and corded electric. Product dimensions are printed as 1 x 1 x 1 cm, with no weight, and that size is the listing line rather than a figure we measured. No plug, trip, enclosure rating or standard is stated, and the model-number field reads 1. Amazon.co.uk shows no customer-review line. Twenty volt-amperes will not supply a mains appliance, and a 1 cm cube is not a credible description of a 220 V winding you would wire into a bench. It is the cheapest row in the set, and it is a poor match for a finished isolation job because the power, the size line and the missing standard sit together.
Pros
- Lowest shelf price in the set at £22.00
- 20 VA and a 1:1 ratio stated in the title
- Surface-mount profile stated on the listing
Cons
- Dimensions stated as 1 x 1 x 1 cm, with no weight
- No standard, plug, trip or enclosure
- 20 VA is far below a mains tool or kettle
- No customer-review line on amazon.co.uk
Best for: Only a comparison of a 20 VA 220 V chassis listing, where you will not treat the part as a portable appliance.
Less suitable: Any plug-in tool, a repair-bench supply, or a buyer who needs a stated BS EN 61558 part and a believable size.
Specifications
- Model
- FUNTLY DB-20VA 20 VA chassis
- Brand
- FUNTLY
- Price
- ∼£22
- Input voltage
- 220 V
- Output voltage
- 220 V
- Continuous rating
- 20 VA
Common questions
What power rating does the listing give?
The title states 20 VA, model DB-20VA, 220 V to 220 V, and a 1:1 ratio. No current in amps is stated.
How is it mounted?
Technical details state plug profile Surface Mount and power source Corded Electric. No enclosure rating is stated.
What size does the listing give?
Product dimensions are stated as 1 x 1 x 1 cm. No weight is stated, and there is no customer-review line.
How we compared
Three isolation transformers on amazon.co.uk were scored from the listing text, not from a winding test and not from star ratings. None of the three has a customer-review line, so the score does not start from stars. The published figure is the display score. A cased 230 V unit with a stated trip, sockets and a BS EN 61558 claim sits highest, then is marked down for Schuko connectors, no duty cycle, no part number and no reviews. A lower price that still states VA and current is the best-value row, marked down for an open chassis, a 220 V plate and no standard. A 20 VA listing with a 1 cm size line sits lowest. A brand story does not add points. The weights below follow the buying order in the digest.
1
Standard part
20%A 230 V secondary needs an isolating transformer for general use, BS EN IEC 61558-2-4. BS EN 61558 with no part number is incomplete. No standard on the listing is marked down. Medical IT, EV separation and a construction site are not covered by that incomplete line.
2
Continuous VA and trip
25%Continuous VA comes first, then any intermittent VA, then the trip current. The 3 kVA title is not treated as an all-day load when the listing states 1.5 kVA continuous and gives no duty cycle.
3
Printed voltage
15%UK public supply in HSE guidance is 230 V. A 220 V to 220 V plate is left as 220 V. None of these listings is scored as a 110 V output.
4
Plug and socket
20%A UK 13 A socket wants BS 1363 and a BS 1362 fuse. A 16 A Schuko plug is the wrong pattern and the wrong current. A chassis listing with no plug is a component, not a finished appliance.
5
Case and enclosure
20%A closed case and a stated trip count for a portable box. An open chassis part with no enclosure and no IP rating does not score as a finished appliance.
Independent review
Last updated: 22.10.2026
8 sources checked
Isolation transformer buying guide
Start with the standard part, then continuous VA and the trip, then the voltage printed on the plate, then the plug. A closed case comes after those. The notes below follow that order for these three amazon.co.uk listings. None of the scores is a winding test, and none of the listings has a customer-review line.
What is an isolation transformer?
An isolation transformer in this set is a mains unit with separate primary and secondary windings, so the output is galvanically separated from the supply. The consumer object is a portable cased unit, usually 230 V to 230 V, with a lead, a socket and a trip. It is for one appliance or a repair bench. It is not a 110 V site transformer, and it is not a [mains isolation switch](/hub/electrical-equipment/mains-isolation-switch), which opens the supply rather than separating the windings.
Best for
- One 230 V appliance or a repair bench, where you already use 16 A Schuko connectors and the load stays inside 1.5 kVA continuous
- A competent person enclosing a stated 0.68 A, 220 V chassis part for a load inside 150 VA
- A reader who wants the 20 VA listing named so it is not mistaken for a portable mains box
Not ideal for
- A UK 13 A socket, a kettle or a mains drill, or anyone treating 3 kVA intermittent as an all-day rating
- A 110 V centre-tapped site supply, medical IT, an EV separating supply, or fixed wiring
- Anyone who reads a floating secondary as safe to touch, or who bonds it to earth and still calls it separated
Mistakes to avoid
- 1
Buying a 230 V isolator for a building site
HSE tells construction work to use cordless tools or 110 V centre-tapped to earth, so voltage to earth does not exceed 55 V. These three listings are 230 V or 220 V to the same voltage. They are not a site transformer.
- 2
Loading the intermittent figure all day
The cased listing states 1.5 kVA continuous and 3 kVA intermittent, and it does not state a duty cycle. At 230 V the 10 A trip is 2,300 VA. A sustained load belongs under 1.5 kVA. A 3 kW kettle is about 13 A, above both.
- 3
Forcing a Schuko plug, or running a tool from 20 VA
A 16 A Schuko plug does not belong in a shuttered BS 1363 socket. The 20 VA and 150 VA chassis parts have no plug and no enclosure. Twenty volt-amperes will not supply a mains tool.
What to weigh up
Standard, continuous VA and the trip
HighA general isolating transformer with a secondary above 50 V AC sits in BS EN IEC 61558-2-4. Part 2-6 is SELV. Part 2-15 is fixed medical IT. Part 2-23 is the centre-tapped site transformer. The Watts Control page claims BS EN 61558 and prints no part number. The two chassis listings state no standard. That incomplete claim is not cover for a medical room, an EV supply or a building site. Continuous VA comes before the intermittent figure.
Voltage, plug and enclosure
HighUK public supply in HSE guidance is 230 V. Watts Control states 230 V to 230 V. SACVXOKD and FUNTLY state 220 V to 220 V. Do not relabel a 220 V plate as 230 V, and do not expect 110 V from any of these three. None describes a centre-tapped secondary. Regulation 35 of the Electrical Equipment (Safety) Regulations 2016 requires a BS 1363 plug, or a non-UK plug with a conversion plug and a BS 1362 fuse, for domestic use on a BS 1363 socket.
Which option suits you?
Three typical situations, each with a recommendation from this comparison.
A small chassis part to enclose
A competent person is fitting a stated 0.68 A, 220 V chassis part into their own enclosure, and the load stays inside 150 VA. The SACVXOKD BK150VA is about £41.99. It has no plug and no standard.
Checking the cheapest row
You are looking at the £22 listing and you need to see that 20 VA is not a portable appliance. The FUNTLY DB-20VA states 220 V to 220 V and dimensions of 1 x 1 x 1 cm. It is not a repair-bench supply.
Common questions about isolation transformers
Which isolation transformer is the top pick in this set?
The top pick is the Watts Control cased unit, about £149.99, model WCPT3000/230/SCHUKO. It is the only listing here that states a GRP enclosure, 230 V to 230 V, 1.5 kVA continuous, a 10 A hand-reset trip and two sockets. The connectors are 16 A Schuko, not BS 1363. Amazon.co.uk shows no customer-review line. The display score is 68. That is not a lab test, and the award is only for being the sole cased row.
How much does an isolation transformer cost on amazon.co.uk?
On these three shelves the FUNTLY chassis part is about £22, the SACVXOKD 150 VA part is about £41.99, and the Watts Control cased unit is about £149.99. There is no higher amazon.co.uk tier in this set. Trade pages outside Amazon showed other BS 1363 units, and those figures are not amazon.co.uk prices. None of the three has a customer-review line. These are the saved listing prices, and they will move.
Is a floating 230 V secondary safe to touch?
No. A floating secondary is still 230 V between its own lines. Galvanic separation changes the earth reference for one item of equipment. It does not make the output safe to touch, and it does not replace proving a circuit dead. A second fault, or an earthed test lead on a repair bench, can remove the earth-fault protection you were counting on. Leave the secondary floating if the aim is separation. Do not bond it to earth and still call it separated.
Will the Schuko plug fit a UK 13 A socket?
No. The Watts Control listing states a 16 A Schuko input plug and two 16 A Schuko sockets. A Schuko plug is the wrong pattern and the wrong current for a shuttered BS 1363 socket. Regulation 35 of the Electrical Equipment (Safety) Regulations 2016 expects a BS 1363 plug, or a non-UK plug used with a conversion plug and a BS 1362 fuse, for equipment intended for domestic use on a UK socket. Forcing the pins damages the socket. A manufacturer name is not a UK plug.
Is the 3 kVA figure a continuous rating?
No. The Watts Control listing states 1.5 kVA continuous and 3 kVA intermittent, plus a 10 A thermal-magnetic trip, and it does not state a duty cycle. At 230 V, 10 A is 2,300 VA, which sits between those two figures. Keep a sustained load inside 1.5 kVA. A 3 kW kettle is about 13 A at 230 V, above both the continuous rating and the trip. Do not paste another maker’s duty percentage onto this listing.
Is an isolation transformer the same as a 110 V site transformer?
No. These three listings are 230 V to 230 V or 220 V to 220 V, with separate windings and, where stated, a floating secondary. A UK site transformer is typically 110 V with the secondary centre-tap earthed, so the voltage to earth is about 55 V. That sits with BS EN IEC 61558-2-23. Health and Safety Executive guidance points construction work at cordless tools or that reduced voltage. Do not buy a 230 V to 230 V isolator as a substitute for a site transformer.
When should you call an electrician?
Call a competent person for fixed wiring, a medical IT system, an EV separating supply, a site temporary supply, a hot or live case, or a plan to re-bond the secondary because of PME. BS 7671 regulation 722.413.1.2 asks for a fixed BS EN 61558-2-4 transformer, one unearthed source and one vehicle. A marketplace Schuko box is not that design. A 30 mA RCD does not replace separation. If the case is already live, stop and do not keep testing it yourself.
Our verdict
In this set of three amazon.co.uk listings, the top pick is the Watts Control cased unit at about £149.99. The display score is 68 because it is the only row that states a GRP case, 230 V to 230 V, 1.5 kVA continuous, a 10 A trip and a BS EN 61558 claim. It is marked down for no reviews, Schuko connectors, no duty cycle and no part number. The best value is the SACVXOKD BK150VA at about £41.99. The display score is 44 because that lower price still states 150 VA and 0.68 A. It is marked down for no reviews, no enclosure, no plug, no standard and a 220 V plate. The FUNTLY at about £22 has no award. Its score is 26. None of these scores is a lab test, and none of the three has a customer-review line.
Best overallView offer
Watts Control 1.5 kVA cased isolator
Only cased 230 V listing in this set: about £149.99, GRP case, 1.5 kVA continuous, 10 A trip, score 68 after Schuko connectors, no duty cycle and no reviews.
Best value
View offer
SACVXOKD BK150VA 150 VA chassis
Lower price that still states 150 VA and 0.68 A: about £41.99, score 44 after no enclosure, no plug, no standard and a 220 V plate.
Editorial
Editor
Isolation transformersElectrical equipmentamazon.co.uk listings
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.
Updated: 22.10.2026
8 sources checked
Guides to isolation transformers
Guides on what to look for, how to use a product, and common mistakes.
Isolation transformer buying guideStandard part, continuous VA, voltage, plug and enclosure, before the product tableBest isolation transformerWhich of the three listings fits a job, and who should skip the setHow to use an isolation transformerOne appliance, the plate, and a secondary left floatingIsolation transformer vs site transformerFloating 230 V against a 110 V centre-tap to earthIsolation transformer for a repair benchOne device under test, and what earthed instruments do
Related comparisons
Sources
Public UK sources from the research digest. Shelf prices are the amazon.co.uk figures in the display file. We did not treat trade-catalogue prices as amazon.co.uk prices.
- HSE: electricity on construction sites (retrieved 22 October 2026)
- HSE: electrical equipment (retrieved 22 October 2026)
- Electrical Equipment (Safety) Regulations 2016, regulation 35 (retrieved 22 October 2026)
- GOV.UK: Electrical Equipment (Safety) Regulations 2016 (retrieved 22 October 2026)
- BSI: BS EN IEC 61558-2-4:2025 (retrieved 22 October 2026)
- IET Wiring Matters: separation and isolation (retrieved 22 October 2026)
- Carroll & Meynell: 230 V to 230 V isolation transformer duty (retrieved 22 October 2026)
- ABL: isolation transformer sizing (retrieved 22 October 2026)
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 are the saved UK listing figures. None of these three has a customer-review line. We did not lab-test these isolation transformers.