

I suspect you're not going to get a nice yes/no answer for this - as there's no clear definition of what makes such a system safe or unsafe in the first place.
As a bit of background there was a thread about the way open-pen devices like this work - Open PEN detection for 722.411.4.1 (iv) - as you seen there are situations where the results are perhaps less than ideal anyway. Increasing the acceptable voltage range will increasing the probability of the system remaining connected in a hazardous situation, but given the original system is not entirely perfect in the first place, whether that constitutes a significant reduction in safety is debatable rather than calculable.
I could see an argument that if the device had some additional mechanism for reducing the risk from shock under broken PEN conditions - not just voltage measuring, but say monitoring the c.p.c. current and disconnecting immediately if hazardous shock levels were present (say >10mA), and as that wasn't compromised at all by the voltage limit change, the overall risk might not be significantly increased.
- Andy.
Thank you very much for this Andy - and I would agree with you that there is no simple yes or no answer here. I am in a difficult posistion due to the fact we have manufacturers stating that voltages can be increased while myself as the installer is left scrambling to understand the comlexities of this decision.
I really feel at a lost at present, the charger I am discussing does have additional monitoring on the CPC so that is a benefit, I am still unsure how I can justify that in terms of upping the voltages - against what is in BS7671? Would you have any thought or comment on that?
I see that in New Zealand the have changed their supply voltage limits because of Prosumer issues from +6% to +10%, while keeping the DNO supply level at +6% to allow for back feeding from solar on longer distribution lines.
see https://www.youtube.com/watch?v=s8RXQERPzMY "The newly announced NZ Grid Voltage Increase explained".
This may give one view on how to explain things, even if it's not directly equivalent.
The other option is to distinguish between a "Fault" and "Disturbance" (aka Dangerous vs Annoying).
Thank you very much Philip, I will have a look at that video.
Hello Philip:
The video was excellent but highlighted a fact I had forgotten about the delivery of electrical power to New Zealand and the UK.
It mentioned that houses are only supplied with single phase power.
Here in the US houses are supplied with split phase power with the two phases being 180 degrees apart giving 110-120 volts and 240 volts. The later being used for electric ovens, heat pumps and driers.
Peter Brooks
Palm Bay FL
True, though I tend now to think of the US supplies as 220V centre tapped :wink:
Hello Philip:-
In my old house the 110 and 240 volt supplies are treated differently.
The 110 is routed to sockets using Al wires while the 240 is routed using copper wires to heavy duty sockets .
Today (1st of August) hurricane supplies are TAX free. This includes small motor/generator sets, used in the event of loss of electrical power.
My memory (as I don't own one ) is that they only have single phase 110 volt output.. Now I will have to go to my big box hardware store to look at them.
Also there are bigger units, which I assume have both output voltages.
Peter Brooks
Palm Bay
I have a difficulty, in that your original question was around how to interpret a provision of BS 7671. I can't, unfortunately, do that. BS 0 prohibits anyone involved in standards making from providing an "interpretation", because in the UK only a court of law can interpret a standard.
In this case, though, I believe what you are saying is that a manufacturer has said their product under specific circumstances is "no less safe" - which is really something for the manufacturer to declare.
In terms of voltage tolerances, we could well be talking about a situation where the charging equipment is subjected to higher voltages than ESQCR provides for (> 253 V), occasionally for long periods, because of renewable generation. This could occur within an installation, in addition to the possibility of it occurring in the network.
The issue in general, is that whilst renewable generation and G98/G99 say it's OK to go as high as 262.2 V without disconnecting PV and similar inverters, thus meaning that parts of an installation are effectively "overvoltage" for periods of time, this is not reflected in product standards that are based on BS EN 60038 ... which still expects the steady voltage to be no more than + 10 % (253 V).
There is also BS EN 50160 to take into account, as well as EMC test standards, which provide for tests for temporary overvoltages, and voltage dips/interruptions. This is accounted for in IET 01:2024 ... but if that has not been adopted by an OPDD manufacturer, there is no "guaranteed ride through" of such conditions.
I have a difficulty, in that your original question was around how to interpret a provision of BS 7671. I can't, unfortunately, do that. BS 0 prohibits anyone involved in standards making from providing an "interpretation", because in the UK only a court of law can interpret a standard.
In this case, though, I believe what you are saying is that a manufacturer has said their product under specific circumstances is "no less safe" - which is really something for the manufacturer to declare.
In terms of voltage tolerances, we could well be talking about a situation where the charging equipment is subjected to higher voltages than ESQCR provides for (> 253 V), occasionally for long periods, because of renewable generation. This could occur within an installation, in addition to the possibility of it occurring in the network.
The issue in general, is that whilst renewable generation and G98/G99 say it's OK to go as high as 262.2 V without disconnecting PV and similar inverters, thus meaning that parts of an installation are effectively "overvoltage" for periods of time, this is not reflected in product standards that are based on BS EN 60038 ... which still expects the steady voltage to be no more than + 10 % (253 V).
There is also BS EN 50160 to take into account, as well as EMC test standards, which provide for tests for temporary overvoltages, and voltage dips/interruptions. This is accounted for in IET 01:2024 ... but if that has not been adopted by an OPDD manufacturer, there is no "guaranteed ride through" of such conditions.
Thank you Graham, with the issue of renewable generation aside, we are seeing issues with the DNOs in that they are stating that the times they will allow over volatge are over certain time periods (meaning so many overvoltages within a set period would result in them stepping down the volatge). The issue here - with chargers that are not auto reset (so to speak) after an over volatge, means a client is resetting a charger multiple times a night. The DNOs are simply shutting off to our requests.
I think with the overall view points on this - the only option I have or will have is to look to install all equipment in accordance with IET -01 and where we have the issue of over voltage we will need to change equipment over.
Thank you very much for your reply.
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