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Kewtech KEWISO3 Safety isolation Unit

The ultimate solution for safe isolation procedures, with a UK specific KT1790 two pole tester. Permanently GS38 with no covers to lose and a 50-690V proving unit.

Next Day Delivery (subject to availability)

£139.95 exc. VAT £167.94 inc. VAT £310.80 inc. VAT
  • GS38 Compliant
  • Phase Rotation Tester
  • LED Indicator
  • Indication of Polarity
  • Tests Up To 690v
  • Case Included
  • 690V Proving Unit
  • Lock Out Kit Included
  • Batteries Included
  • FreeDelivery
  • 30DayMoneyBack
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Kewtech KEWISO3 Safety Isolation Unit


The ultimate solution for safe isolation procedures, with a voltage only UK specific KT1780 two pole tester. Permanently GS38 with no covers to lose. A Kewprove 3 proving unit with a transparent window allowing the unit to be used and observed whilst in the case. The inclusion of a Kewlok universal lock off device with selectable combination enables you to lock out most MCB's, complete with warning labels.


The Kewtech KEWISO3 Isolation Kit Comes Supplied With:

  • 1 x UK specific KT1790 two pole tester
  • 1 x Kewprove 3 proving unit with a transparent window
  • 1 x Kewlok universal lock off device with selectable combination
  • 2 x Lock-out Warning Labels


A Closer Look at the Contents:

KT1780 Tester

  • AC & DC Voltage tests up to 690V
  • Clear Oversize luminous LED indication
  • 0.1 V LCD resolution display
  • Soft to touch overmoulded rubber body
  • Continuity Test
  • Self diagnostic test
  • Single Pole phase test
  • Phase Rotation test
  • Polarity indication
  • Auto power on/off
  • IP65 rating protects against Dust & Water ingress
  • Designed to the new international safety standards IEC 61243-3 & IEC 61010-1



  • One size fits most MCBs and toggle type main switches
  • Easy to use combination lock
  • User selectable integral combination padlock for memorable combination numbers
  • No need for separate lock and no keys required.
  • Saves having multi piece lock out kits
  • Comes with two warning labels that can be secured to the shackle and give user information


  • High output will drive even the most high current voltage detector
  • Instant ramp up and then step down will prove 690, 400, 230, 120 & 50v voltage levels

Carry Bag

  • Durable carry bag with a shoulder strap and transparent window for the proving unit. Space to carry extra tools.


Ouput Voltage 180V in to 6.8Ω, 720V - 820V in to 10M Ω
Operating Conditions -10 to 40C, 70% RH
Dimensions W: 65 x H: 120 x D: 45mm


Kewtech KT1790 Tester
LED Tolerance 7 ± 3V (12V LED), 18±3V (12V LED), 37.5V±4V (50V LED)
75%±5% of nominal voltage (120/230/400/690V LED)
LED Response Time <0.6s at 100% of each nominal voltage
LCD Auto/Range Resolution 300V (6.0-299.9)/0.1V, 690V (270-759AC/710DC)/1V
LCD Accuracy (23+/-5°C)  ±1.5V (7-100V), ±1% ± 5 digit (100-690V), AC (16-400Hz), DC(±) 
LCD Response Time <1s at 90% of each voltage
Peak Current Is<3.5mS (at 690V)
Internal Battery Consumption Approx 80mA (battery 3V, measuring 690V AC)
Measurement Duty 30S On (Operational Time) 240S Off (Recovery Time)
Voltage Range 100-690V AC (45-100Hz)
System Three-phase 4-wire system
200-690V phase-to-phase
(100-400V earth-to-phase)
AC 50/60Hz
Detection Range 0-400kΩ + 50% (23 ± 5°C)
Test Current Approx 1.5μA (battery 3V, 0Ω)
Internal Battery Consumption Approx 80mA (battery 3V, 0Ω)
 Operating Reference Conditions  -15 - 55°C no condensation max 85% RH
Storage Reference Conditions -20-70°C no condensation max 85% RH
Safety Standards IEC 61010-1:2010, IEC 61243-3:2010, IEC 601010-031: 2008
Category: CAT III 690, CAT IV 600V pollution degree 2
IEC 61557-7: 2007
IP Rating IP65 (IEC60529)
Dimensions 243 x 64 x 26mm
Weight 190g (including batteries)
Batteries 3V (2 x 1.5V AAA/LR03)

Orders requiring calibration 

Whilst we take the greatest care to get all orders dispatched and delivered to you in the stated time frame, orders received PM and requiring
calibration may on occasion miss dispatch that day, according to the complexity of the calibration. Be assured they will ship on the next dispatch
this in most cases should not add more than 24 hours to your delivery.

Bank/Public Holidays

Predicted delivery times are based on regular trading days Monday to Friday. Public holidays, bank holidays and weekends are outside the usual scope 
of our dispatch and subject to activities/holidays of our carriers and therefore may incur additional days lead time to your order.

*UK Mainland (Temporarily revised June 2020)

Please note that regrettably, we have had to realign our delivery service options to those available from our carriers.
During the current situation surrounding the effects of the Coronavirus pandemic, logistics from every company are under immense pressure to deliver goods on time.
We have taken the decision to temporarily limit our services rather than let our customers down.
We hope you will understand our position on this and we apologise unreservedly for the inconvenience we know this will cause.
We look forward to restoring our full delivery service schedule just as soon as we are able.

Standard FREE 1-2 Day Courier Delivery – UK Mainland only - Zones A & B

Included in the price for all orders over £75.00 (exc vat). Sent using express courier, delivered within 1-2 working days from the date of your order, subject to availability.


Next Day Anytime Delivery (Excluding Saturday & Sunday) – UK Mainland only - Zones A & B
Sent by express courier, delivered next day (excluding weekends) from the date of your order, subject to availability.


Orders must be placed before 3:00pm for a qualifying next day delivery and a telephone number supplied, subject to availability.

New Postage Map Sept 2018>

Delivery Surcharges

Because of the high cost of carriage, we need to apply a surcharge on all deliveries made in the following regions bringing the carriage charges to:

  • Zones A & B  - Mainland delivery rates apply. 
  • Zone C - Scottish Highlands (Charges are calculated at the checkout).
  • Zone D - Outer Hebrides, Orkney Isles, Shetland Isles, Isle of Man, Scilly Isles, and Channel Islands (Charges are calculated at the checkout).
  • Zone E - Northern Ireland (Charges are calculated at the checkout).
  • Zone F - Republic of Ireland (Charges are calculated at the checkout).

Offshore Services

All offshore deliveries are a 2 day service as standard. This includes Channel Islands, Northern & Southern Ireland, Scottish Islands, Isle of Man and the Scilly Isles.

International Delivery

International delivery charges are automatically added to your order at the checkout. For any questions regarding international deliveries please contact us at


All export inquiries should be directed to the export division before placement of order.

If no shipping option is available to your selected country please call us FREE on 0800 0224 060 to purchase your items.
All stated prices are subject to VAT at the current rate where applicable E&OA