RoadTest: VeriSafe Panel-Mtd. Voltage Tester
Author: shabaz
Creation date:
Evaluation Type: Test Equipment
Did you receive all parts the manufacturer stated would be included in the package?: True
What other parts do you consider comparable to this product?: Manual test tools (voltage testers, multimeters)
What were the biggest problems encountered?: No problems encountered
Detailed Review:
When doing electrical work there is a real risk of the power accidentally being left on before starting work. Dropping concentration for a few seconds is enough to cause death. Over the weekend I helped a friend repair his hot water boiler, and despite knowing that the power had been switched off, and verifying with a meter, I still felt uncomfortable enough to avoid touching any wiring unless absolutely needed. A fuse of perhaps 5A was fitted, and it would not have helped protect us in the event that the wiring was accidentally still live. It is easy to make a mistake and switch off the incorrect circuit breaker. The dangers are multiplied further in an industrial environment where there is a lot more live wiring, often three phases, and far higher current consumption.
What we call a small ‘consumer unit’ or fuseboard in homes in the UK (nowadays there would be circuit breakers and residual current devices (RCD) fitted) is replaced with large cabinets in labs and factories. Wiring the size of pipes is plumbed into the buildings, requiring digging huge trenches. Everything is on a huge scale.
According to the US National Fire Protection Association (NFPA) Standard for Electrical Safety in the Workplace (NFPA 70E), establishing a safe work environment involves testing for absence of voltage, and this requires that whatever test equipment you use (voltage tester, multimeter and so on) is verified against a known voltage source both before and after the absence of voltage test is performed. The procedure is quite involved; each phase must be verified, phase-to-phase, and phase-to-ground. Before and after each test, the test equipment must be verified to be functioning against a known voltage source. That’s a lot of test steps!
The Panduit ‘VeriSafe’ absence of voltage tester is designed to do all that; it automates the verification procedure, saving the user from having to manually perform these steps, saving time, money and reducing the risk of error. It is basically a device that is permanently wired into the enclosure or controlled area, and it becomes very convenient to do all the tests using a single button-press.
Although the NFPA 70E standard is for the US, there could be applicability for the VeriSafe tester in other countries with similar requirements.
I was keen to explore this unusual but potentially life-saving product. Here in the UK, I do have some experience with Panduit products, in particular their 19-inch racks. They are known for high quality.
This short (5-minute) video provides a quick overview and demo of the VeriSafe solution:
One of the labs that I explored contained power distribution units (PDUs) with an emergency cut-off button, and indicator lights for each phase:
These PDUs are used to distribute power to aisles of electrical equipment in labs and factories. In this example, a server room is being powered:
Sometimes it is achieved with under-floor cabling; here cable trays at ceiling level are used:
There are connectors to feed the power all along the aisle:
The power requirement to run the server equipment and to cool it all is fairly high! The risks are severe for any engineer who doesn’t ensure a safe work environment when working inside the power cabinets.
The VeriSafe solution arrived in a very large box, dwarfing my lunch:
However, there was a lot in the box – predominantly the cables. The coloured wires are used to connect to all of the phases of power inside the cabinet and to the earth too. Each connection is a pair of wires, i.e. doubled-up for providing a reliable test that can even identify if a cable has become disconnected. The system checks for continuity between the two wires in the pairs basically.
It was great to see a very comprehensive 18 page user manual (entirely in English, although the safety warning information page is also in French) inside the box. It is in full colour, with detailed diagrams showing how to perform connections for different wiring systems (three phase delta, wye, single phase and different earthing systems that may be encountered). A set of round stickers is also supplied that are only needed if the VeriSafe product is being installed with different language requirement, and a yellow set of stickers in multiple languages, that has a brief test procedure which can be stuck in a visible location. A nice touch is the QR code on there, for getting all the detailed product information immediately using a mobile phone. Note that it is wise to do this and only use the paper manual as a guideline. The latest VeriSafe online user manual (PDF) should always be used to install this VeriSafe product.
The VeriSafe system consists of two key parts; the large isolation module with the multi-colored wires, and a yellow indicator module. The isolation module is wired up to all the phases and to the earth, and then there is a single interconnect cable (with RJ45 style connectors) that joins it to the indicator module that is mounted in a user accessible location. The system is Category 3 (600V) rated.
The supplied black 60cm interconnect cable is called the ‘System Cable’ in VeriSafe terminology. Although it looks like it could be replaced with any RJ45 network cable, I believe it is incompatible, and the right-angle part is quite unusual, it fits very deeply inside the indicator module (there is a clip on the indicator module that needs to be partially pulled upward (forcefully) if the cable ever needs removing; it won’t accidentally fall out with vibration).
A supplied 3.6V AA sized lithium battery fits inside the indicator module. There are actually a couple of rubber seals (and a small amount of silicone grease), so it is unlikely that dust will get inside this module in ordinary use, and it is approved for wash-down (IP66). The type of plastic wasn’t marked, but it feels very tough.
An electrical installer would not need any unusual or additional tool to deploy VeriSafe, apart from perhaps a drill and a punch for a 30mm hole and a 2mm notch. Apparently, this is a standard sized knockout, so no tool may be needed to make the hole. A depth of 90mm is needed behind the knockout for the indicator module. The wires from the isolation module have no supplied connectors, and the wires would be attached to each phase using existing approved connection methods. The user manual goes into the detail of precautions to take and how to route the wires. The isolation module can either snap onto a standard rail (DIN rail) or can be screwed to a surface using three screw holes (screws not supplied; #8, or M4 is the ideal fit for the holes).
The indicator module has a simple interface, with just one button to press to start the test. When the wiring is normally live, there will be three lights glowing red to indicate that dangerous voltages are present. When the test is running, a central triangle flashes and then pauses for a few seconds, and then flashes out a code if the environment is not safe to work on. The code tells you (by the number of flashes) if the wiring is live or there is some cable fault.
On the other hand, if the environment is safely powered down, then a green outer partial ring glows. That is the only scenario where you can be confident that there is no power, and the environment is safe (engineers should still take precautions however – one can’t predict if someone else will override the power cut-off for example, while you are working. Sensible engineers will place warnings at a minimum, and follow their procedures for ensuring no-one else can switch the power on inadvertently).
A nice feature is that the isolation module has four screw terminals that are for two relay contacts that close whenever the system is indicating green. This allows for redundancy by wiring the contacts in series, and the connections can go to a logging system or an industrial IoT system for reporting.
To test the system, I didn’t use a real three phase supply – most individuals do not have access to this, and I wanted to test it in a safe environment before subjecting it to a real mains test. So, I used a low voltage three phase system. Instead of 208/380/415V RMS (depending on what country you're in), it offers around 6V RMS phase-to-phase! Super-safe, ideal for simulating the power into a factory. Another cool way is to use a variable frequency drive and three step-down transformers.
Each of the three phases from the test 3-phase supply were connected to pairs of wires attached to the isolation module. My three-phase test supply has a neutral connection, which I treated as the earth connection. So, all eight wires (two for each phase, and two for earth) from the isolation module were connected to the three-phase test supply.
Next I proceeded to run some tests including single points of failure such as a disconnection of one of the wires in a pair from the isolation module. The VeriSafe system behaved as expected. Note that multiple failures are not guaranteed to provide correct indication; for an example, see Peter's RoadTest Review where he identifies and details a scenario where a broken wire falls on a metal chassis connected to earth. There are specific rules on installation that must be followed to prevent a double failure (e.g. using wire ties to prevent a loose wire from falling where it shouldn’t). For situations where more than one fault must not be tolerated, I wouldn’t rule out the idea to install two VeriSafe units, and have a procedure where both units must provide a green signal and both units are to have their relay contacts wired in series to a management platform.
With some practice gained in using the VeriSafe product with the safe three-phase supply, I proceeded to hook it up to the single phase real mains supply at home.
Here the live and neutral wires are connected to pairs of wires from the isolation module, and the third phase pair and the earth pair are wired together (this is detailed in the VeriSafe user manual). With the mains power switched off, I got the green light as expected.
Next, I switched on the mains supply, and the red hazardous voltage indicators came on, again as expected. Pressing the test button caused the triangle to flash a code indicating that voltage was present.
I was curious, how reliable is the unit, if it is permanently connected in electrical cabinets? The VeriSafe product is designed to achieve a Safety Integrity Level of SIL3, which for this continuous operation product means a probability of failure per hour to be in the range 10-7 to 10-8. In other words, if you had a hundred of these devices deployed, then you could expect to perhaps have to replace one in ten years of continuous operation. Note: I am not a probability or a reliability expert, so please do run the sums if you need to, and let me know in the comments below.
In contrast a multimeter is not permanently energised; it is only energised for the length of the tests. However, such a direct comparison is meaningless; an engineer will still use a multimeter and other test tools where needed, and furthermore the risk of not performing the test procedure correctly in ten years is far higher when there are many manual steps to perform, so I’m convinced that the VeriSafe product serves a valuable purpose.
Digging further into the safety aspects, the VeriSafe product is designed to meet immunity requirements for safety related systems based on IEC standards, and meets software requirements for safety related systems too, to IEC standards (the full set is listed in the technical specifications section in the VeriSafe PDF user manual). In terms of electrical requirements, there is no need to have an inline fuse when wiring the isolation module. It is tested to withstand transients of up to 6kV.
I was keen to see the internal build quality; there are four screws that hold the IP20 rated isolation module together.
The top board performs the majority of the isolation task. The other side of that board contains some physically large disc capacitors, which I believe are Vishay, rated X1 and Y1, designed for permanent connections.
The other board contains the processing circuitry. The connections between the boards are with 0.1 inch header pins and sockets, i.e. a board interconnect technique known for reliability (the same techniques are even seen in military equipment).
I love that Panduit thought out-of-the-box to made things safer for engineers in a high risk environment. I was very surprised at the level of sophistication for the VeriSafe Absence of Voltage tester. It is straightforward to install (but read all the instructions, and get familiar with it!) and extremely easy to use, I liked that there is no ambiguity with the indications, a green light is mandatory to determine that the environment is safe to work in (as mentioned, it is wise to still take precautions), and that it collapses multiple manual test steps into a single button-press, eliminating user error in most cases.
The internals look well constructed too, and there should be an easy return-on-investment exercise for engineers who know how long it takes them to run manual absence of voltage tests. The risk of making a mistake is of course dramatically reduced, and that should be a huge motivator to evaluate VeriSafe and decide if it is worthwhile to deploy it.
Top Comments
Hi Shabaz,
This is a great road test. I will have to show this to my son who works in the dangerous conditions of a 3 phase industrial factory.
John
shabaz a very good detailed review and inspection of the VeriSafe. I have been looking at the device for a while now following the initial road test by peteroakes and to be honest, I am not convinced that…
Hi Donald,
Thanks for the comments! It is clear you're committed to contributing valuable knowledge, and I appreciate it.
I am not based in the US, so this was quite a challenging product to review,…