Panel/Switchgear Yellow Electricity Warning Labels

AJJewsbury:

BS 7671 regulation 514.10.1 seems to be phrased all in terms of nominal voltages, so I would expect notices in compliance of that regulation at least to show nominal. Note that it's unusual to actually need such a notice from a BS 7671 point of view these days - since the requirement only applies where the voltage exceeds 230V nominal to earth - thus nothing is needed for either single phase 230V nominal systems (despite possibly up to 253V being present), or normal three-phase 230/400V systems despite the nominal 400V between lines.

  - Andy.

More importantly, nominal voltage to Earth ... meaning that a typical 400 V three-phase system need not have a label.


Panels manufactured off-site will most likely be constructed to BS EN 61439-series and/or BS EN 60204-1 - so labelling should comply with the requirements of the respective standard.


I don't think there is a specific requirement in BS EN 61439-series for a specific label, but BS EN 60204-1 requires just the ISO 7010-W012 symbol, (just that, alone - I guess you could indicate voltage if you wanted, but there is no requirement) on any enclosure that contains equipment that might give rise to electric shock. There are a few cases where the warning sign is not required.


Some contract specifications have labelling requirements over and above the standards, however.


The minimum size of text and symbols, and recommendations for fonts, on labels is now addressed by BS EN 82079-1.

AJJewsbury:

BS 7671 regulation 514.10.1 seems to be phrased all in terms of nominal voltages, so I would expect notices in compliance of that regulation at least to show nominal. Note that it's unusual to actually need such a notice from a BS 7671 point of view these days - since the requirement only applies where the voltage exceeds 230V nominal to earth - thus nothing is needed for either single phase 230V nominal systems (despite possibly up to 253V being present), or normal three-phase 230/400V systems despite the nominal 400V between lines.

  - Andy.

Andy,


Ok so for example:


> power supply to a motor


> 690Vac nominal voltage U 


> junction box installed next to the motor for the purposes of reducing the cable cross sectional area so that the supply cable fits into the motor 


As per BS 7671 regulation 514.10.1 the junction box would have to be fitted with a warning of the maximum voltage to earth.


So in this example the label would at least state 400V as this is the nominal voltage value for Uo however as BS7671 514.10.1 requires that the maximum voltage be stated then this voltage warning label may be required to state all the way up to 440 (690V phase/phase +10%) 759V if indeed that is the maximum voltage at that junction box.


Do you agree ?

So in this example the label would at least state 400V as this is the nominal voltage value for Uo however as BS7671 514.10.1 requires that the maximum voltage be stated then this voltage warning label may be required to state all the way up to 440 (690V phase/phase +10%) 759V if indeed that is the maximum voltage at that junction box.

AJJewsbury:

So in this example the label would at least state 400V as this is the nominal voltage value for Uo however as BS7671 514.10.1 requires that the maximum voltage be stated then this voltage warning label may be required to state all the way up to 440 (690V phase/phase +10%) 759V if indeed that is the maximum voltage at that junction box.

Humm tricky. If you look at chapter 44 you could decide that the maximum voltage present could be a lot higher again (if you were to take account of all sorts of LV and HV fault conditions - let alone switching or lightning spikes). But that's getting silly (IMO), so my personal interpretation is that they're only asking for a maximum within the context of nominal voltages. It also specifies that the warning should be of 'the maximum voltage to earth present is clearly visible' (my emphasis) - so if it's 690V L-L I think I'd expect a 400V label in that context (690/√3) .

 

   - Andy.

Andy,


Ok yes phase to earth. It would really clarify things if BS7671 514.10.1 used the term nominal instead of maximum. As maximum voltage for the example circuit could be (690/√3) + 10% as per BS EN 60038. I am going to dig a bit further an see if I can find something definitive. Seems a bit odd that there are so many companies selling 230V yellow warning labels if BS7671 does not require them to be installed, maybe they are required under the standards referenced by gkenyon but I have not been able to find an evidence for this in BS 61439-1, BS 61439-2, BS 61439-3, BS 61439-6 thus far.

mapj1:

Though I'd have to say I do not like it - as for a long time we used to put  put 400V (or 415V or 440V depending who did it) on boxes with 3 phases where the phase to phase voltage was 400, so you could get similar labels on both cases, and possible confusion in an old building.

I do prefer to see the star/delta voltages  so 230/400 or 400/690 or 690/1200 (this last not seen in the UK to my knowledge, only seen once in  a large German Factory myself, along with Achtung Hochspannung Lebensgefahr labels ) as it is less ambiguous, though I agree it is not what the modern standards request.

 

mapj1‍ 


I take it those labels where the phase to phase voltage was 400 were being applied as part of a client request and not ‍a requirement of some BS standard ?

Mike M:

AJJewsbury:

BS 7671 regulation 514.10.1 seems to be phrased all in terms of nominal voltages, so I would expect notices in compliance of that regulation at least to show nominal. Note that it's unusual to actually need such a notice from a BS 7671 point of view these days - since the requirement only applies where the voltage exceeds 230V nominal to earth - thus nothing is needed for either single phase 230V nominal systems (despite possibly up to 253V being present), or normal three-phase 230/400V systems despite the nominal 400V between lines.

  - Andy.

Andy,


Ok so for example:


> power supply to a motor


> 690Vac nominal voltage U 


> junction box installed next to the motor for the purposes of reducing the cable cross sectional area so that the supply cable fits into the motor 


As per BS 7671 regulation 514.10.1 the junction box would have to be fitted with a warning of the maximum voltage to earth.


So in this example the label would at least state 400V as this is the nominal voltage value for Uo however as BS7671 514.10.1 requires that the maximum voltage be stated then this voltage warning label may be required to state all the way up to 440 (690V phase/phase +10%) 759V if indeed that is the maximum voltage at that junction box.


Do you agree ?

Regulation 514.10.1 requires you to consider U₀ (nominal line voltage to Earth), not U (nominal line to line voltage)

Seems a bit odd that there are so many companies selling 230V yellow warning labels if BS7671 does not require them to be installed

AJJewsbury:

Seems a bit odd that there are so many companies selling 230V yellow warning labels if BS7671 does not require them to be installed

The wiring regs used to require them (at least 415V ones where over 250V was present between phases) but the requirement was gradually watered down over the years (including one period where the wording wasn't at all clear) so a lot of people felt more comfortable continuing label things in the same way as they were originally taught (and of course wholesalers don't discontinue things if they still sell).

   - Andy.

An organisation's electrical maintenance / operational safety procedures may require the labels as a warning for their maintenance electricians - there is certainly nothing to prevent this approach in the standards.