Hello all
Please could anyone advise of any issues for installing single phase EVC's from a 3 phase supply.
Proposing there are 6 x 7kW chargers that are located adjacent to each other and wired from individual phases of a 3-phase supply in a local feeder pillar.
Each single phase charger circuit is protected separately in accordance with 722.533.101. The query is if there are any comments on the adjacencies of the vehicles given they are wired on separate phases?
Thanks in advance
Thanks Graham, appreciate your input.
Risk is still there but managed and with correct labelling
I did not say it required (or could be managed with) labelling. I said it's now considered not an issue because the risks associated with this particular hazard (simultaneous contact with live conductors of two phases in separate pieces of equipment at once) have to be managed in other ways. There's no requirement in BS 7671 to put a voltage warning label on a 400 V 3-phase AC charging point either (but of course it may be provided if a risk assessment says otherwise).
Providing a label indicating a potential danger or hazard would be a Warning Notice (this is reflected in BS 7671:2018+A2:2022) ... Warning Notices are, certainly in places of work, governed by the Health & Safety (Signs and Signals) Regulations, and therefore, except in cases where required by BS 7671 or another applicable standard, should only be applied as a result of a risk assessment, and then only where the Hierarchy of Controls has been applied to the relevant hazards. Safety signs are a last resort, and not a "catch all".
I would also note that warning 'ordinary persons' of the presence of 400 V AC, particularly without the relevant symbol (BS EN ISO 7010-W012 on a safety sign or IEC 60417-6042 where the manufacturer applies to equipment) without some further accompanying informative text, may well be pretty meaningless to most people.
514 refers.
Well, I disagree. Regulation 514.10 clearly identifies a "warning notice" for "voltage", but only on equipment or an enclosure within which the nominal voltage to earth exceeds 230 V, and even then only where the voltage would not be expected. In a three-phase 400 V system, the nominal voltage to earth does not exceed 230 V (it is 230 V).
If you put a notice on a single-phase charging point, that 400 V exists within it, that would not be true in any case ...
The Regulation is clearly not there to identify the fact that in an area, it's possible to simultaneously touch equipment on two phases!
Surprising the number of folk in the industry that don’t know that. I still see it on specifications, although I suppose designers are quite at liberty to go above and beyond 7671 requirements.
Agreed ... but would also point out the safety legislation aspect of this, and also the potential uselessness where used to advise ordinary persons.
Turning this on its head, presence of a voltage warning notice in this type of installation accessible to ordinary persons would make me ask whether there's another issue to be investigated, and perhaps look harder for "the problem" (sometimes safety signs are used when someone knows something's not right, as a "stop-gap" that becomes a "permanent feature").
What about one of these down on the farm when appropriate, but not actually a requirement?
480 V TPN, or centre-tap single-phase, or 2-phase etc., would be in excess of 230 V to earth ... so if it's on the relevant equipment, Reg 514.10 would be OK for that ... alternatively, as I said, a Health & Safety Risk Assessment might have required it.
However, I don't think the particular sign you have illustrated here meets the requirements of the UK standards for safety signs (Red is a prohibition colour or fire safety colour, not warning, and the 480 V ought to be on a yellow background). It therefore does not meet Regulation 514.9.2, and arguably also the requirements of the Health & Safety (Signs and Signals) Regulations.
The web-site itself provides an explanation of why it doesn't meet UK requirements - it's a USA warning signs to ANSI Z535.4
Right sign, wrong format?
And I did not mention warning notices!!
However in terms of that, whether a requirement or not I would always err to avoid any confusion which is what the regulation requires.
In terms of labeling in my comment and what was intended, perhaps i should have been more specific. Call me old fashioned but I would much prefer to attend to an installation whether to inspect or maintain that was labelled correctly using functional labelling clearly and permanently fixed on all switchgear and equipment. Enhances safety, saves time, and avoids confusion.
This whole labeling debate regarding warning notices, whilst useful and informative was not what was intended and it seems has been jumped on by various persons joining the post!!
For me it is good practice, the chargers are remote from main switch-gear. 514 refers.
Hopefully that clarifies.
That sign , or an UK styled version of it, might be more or less OK for a split single phase supply 230-0-230 common on farms where the DNO bottled at the expense of bringing the 3rd HV wire the last 10km or so. But actually (if we think we should or not) we are not in the habit of labeling low voltage installations except those that are unusual in some way. We all expect 230 (well 200 to 250 ish measured ) relative to earth and only normally make a note when it isn't - for example 400/690 or 690/1k2. That said we have a box here with "Danger 12V" on it which makes me chuckle. It's not even high current...
M.
Well and truly off the subject.
As @perspicuous would point out it is declared as 240-0-240 volts, so is an oddity, but common on his jobs.
Agreed, if it's 240 V nominal to Earth, then the sign is appropriate, otherwise if it's 230 V nominal to Earth then the sign is not needed to comply with the requirements of BS 7671,.
BUT ... if it's 230 V nominal to Earth, surely that's 460 V and not 480 V ??????
Good question, doing an internet search brought up the National Grid website, they have taken over from Western Power Distribution as our local DNO.
Low voltage connections (up to 1000V)
The following standard voltages apply:
The voltage should remain within +10% and –6% of these figures.
connections.nationalgrid.co.uk/.../
So it does seem we are back to it being 230 volts to earth on all systems, but with some possibly unexpected voltage between lines.
The ESQCR is clear enough regards the declared voltage of low voltage supplies:
27.—(1) Before commencing a supply to a consumer’s installation, or when the existing supply characteristics have been modified, the supplier shall ascertain from the distributor and then declare to the consumer—
(a)the number of phases;
(b)the frequency; and
(c)the voltage,
at which it is proposed to supply electricity and the extent of the permitted variations thereto.
(2) Unless otherwise agreed in writing between the distributor, the supplier and the consumer (and if necessary between the distributor and any other distributor likely to be affected) the frequency declared pursuant to paragraph (1) shall be 50 hertz and the voltage declared in respect of a low voltage supply shall be 230 volts between the phase and neutral conductors at the supply terminals.
The Electricity Safety, Quality and Continuity Regulations 2002 (legislation.gov.uk)
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