On the basis that although it's Friday, you've mentioned the US Lucy, I'll bite on this. Perhaps the need for live testing that exposes the tester to potential contact should be questioned first?? What are you doing, checking how conductive the tester might be? Frank Hallett

I nearly put in the original message that there is no intention to "work" live, however during fault finding electrical workers often have to test live to find the fault - this is why I referred to" live testing". This testing is happening in the UK but the company is US owned and I have had to have long discussions with the US about how it is not acceptable to work live here, although they seem to have less of a problem with this scenario in the US. Of course live testing does mean you're working near a live conductor using equipment to analyse the fault. From our risk assessments for this I know that workers frequently live test AC: 0-50V Ripple free DC:0-120V, but only test AC: Above extra low voltage -1000V, Ripple free DC:- Above extra low voltage – 1500V under permit. They never work above these voltages. The concern appears to be around arcing under these conditions and the potential for the clothing to catch fire. If anyone does know the answer I would be grateful for some references too (I know I don't ask much!) Thanks for your help so far. Lucy

The work is in factory environment - a couple of sites but it's all maintenance of manufacturing equipment. We don't work on the electrical distribution equipment (that comes under facilities) but on electrical circuits on the manufacturing machines Lucy

Hi Lucy You could point out to your colleagues in the US that we do not have a death penalty in the UK. As stated above the US legal framework is different, If you frequent the international forums on LinkedIn you will soon see different ads for Arc Safety programs and Arc PPE. The US fatality stats for electrocutions at work are 5 times higher than ours....so I would take their advice in that context. A US person in the electrical trades from what I remember would not have as rigorous or demanding a route to qualification as a 17th edition qualified spark in the UK. Nomex is a good idea, fault currents can still happen. Jeff

There is a large difference between the National Electrical Code (NEC) & the EU & UK. Requirements. Firstly, as BS7671 has been mentioned above, be aware that this does not cover a LOT of manufacturing equipment, Lucy, you don't state your industry, but, humour me, and let me say for now it is Automotive. BS7671 does not apply to the machine tools seen in the automotive industry. You also need to understand the potential energy at the point of test. At the origin of the installation under BS7671, you could see very high potential fault currents, however, these will almost certainly be limited by network design by the Distribution Network Operator (DNO) to be <35kA line to ground in your area. The further you move away from the origin, the lower this potential fault current becomes. Now at a typical Automotive machine tool, you could have 24, 48V d.c., 24, 48, 110, 230 & 400V a.c. Now anything on the control circuits of the machine, unless it is very old will have further energy limitation by virtue of how the reduced voltage is derived. d.c. Supplies can only deliver the potential fault current that can be generated by their respective power supply generation devices. Typically switched mode power supplies (SMPSU). I would be amazed if there is sufficient energy to create an arc flash at these supply levels. I've tried and failed to get this to happen. Don't ask! Now going up to 110/230 V a.c. Control, if the machine is constructed to CE requirements, then there will again be a "device" between the control system & the mains supply, this again will provide current limiting. BS EN 60204-1 requires that any control supplies are fed from a transformer (Tx) / power supply (PS). Compliance with this standard (Std.) is "required" for CE marking. Now, this Std. Also requires that the PS or Tx has over current circuit protective devices (OCPD) on the input & output of the device. Now these OCPD's also have current limiting properties, as do ALL circuit protective devices. This is known as the energy let through, and is described in Amp squared seconds. These are just SOME of the things that go to reduce the energy available at a typical manufacturing machine tool to a level where it is IMHO impossible to instigate an arc flash on the control circuits. Please note we are at this stage only talking about control circuits at this stage. There is more, but, it is Saturday evening, and I'm about to pop off for some dinner! ;)