Author Topic: lightning and exclamation mark power shock warning symbols  (Read 928 times)

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Offline waveman

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lightning and exclamation mark power shock warning symbols
« on: October 21, 2021, 08:20:35 pm »
Hello,
I am looking for information of the lightning an exclamation mark hazard warning symbols that we see on 110V input to devices- what they mean, which ones are required. What standard document do I need to get?
 

Online ejeffrey

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Re: lightning and exclamation mark power shock warning symbols
« Reply #1 on: October 21, 2021, 10:50:12 pm »
The left is "general hazard" and the right is "electrical hazard"

I'm not sure when or if they are actually required.  You don't generally see them on consumer equipment so I'd guess that it is an OSHA / workplace safety issue than a product safety issue.
 

Offline Someone

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Re: lightning and exclamation mark power shock warning symbols
« Reply #2 on: October 22, 2021, 03:37:24 am »
IEC60417 and ISO7000 have the symbols themselves, but other standards say where/how they have to be used.
 

Online TimNJ

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Re: lightning and exclamation mark power shock warning symbols
« Reply #3 on: October 22, 2021, 05:28:45 pm »
Under IEC62368-1, these types of symbols are called instructional safeguards. You can't (or wouldn't want to) rely upon an instructional safeguard to provide essential safety, in most cases. After all, an ordinary person may completely not see or understand the symbol(s) at all. In fact, I do not believe any standard lets you "protect" ordinary people from electric shock, by means of an instructional safeguard. For ordinary people, electric shock risk must be mitigated by "real" countermeasures, i.e. isolation, voltage limitation, and leakage current limitation.

However, some products (or situations) are inherently more dangerous than others and you cannot remove the risk completely. For example, equipment which needs to remain powered while being serviced may present some risk to the skilled person involved. In this case, an instructional safeguard may be used to warn the skilled person of potential danger.

So, practically speaking, these types of symbols probably make the most sense when directed at a skilled/trained person. For instance, they can be placed on an access panel door, or added to a PCB which carries mains or high voltage. You can put it on the enclosure of your product, but that somewhat implies that the product (as a whole) is not intended for ordinary people.

If you have access to it, I think IEC62368-1 actually does a pretty good job at covering risk mitigation. They address different types of "energy sources" and different energy levels of each type. Off the top of my head, it discusses:

ES: Electrical source (shock hazard)
TS: Thermal source
PS: Power source (actually not really sure the difference between TS and PS)
RS: Radiation source (X-rays, etc.)
MS: Mechanical source (moving parts, etc.)
 

Offline waveman

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Re: lightning and exclamation mark power shock warning symbols
« Reply #4 on: October 25, 2021, 05:11:55 pm »
Hello,
Thanks all for your replies.

TimNJ
I have access to IEC61010 (safety requirements) and 61508 (functional safety). I found in 61010 the two symbols in a table. I didn't find when we have to put the electrical shock one.

>If you have access to it, I think IEC62368-1 actually does a pretty good job at covering risk mitigation.
Thanks for that. With google search on IEC62368-1, it says the the IEC62368-1 replaces  IEC60950-1. I have IEC60950-1.

I have the AC power main input and one high voltage output plus other small voltage input ouputs.  I have to decide on how high I should limit the high voltage output and what kind of warning symbols I should put.

ejeffrey
>You don't generally see them on consumer equipment so I
The product is to be sold to physicists.
 

Online TimNJ

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Re: lightning and exclamation mark power shock warning symbols
« Reply #5 on: October 25, 2021, 07:58:47 pm »

TimNJ
I have access to IEC61010 (safety requirements) and 61508 (functional safety). I found in 61010 the two symbols in a table. I didn't find when we have to put the electrical shock one.

>If you have access to it, I think IEC62368-1 actually does a pretty good job at covering risk mitigation.
Thanks for that. With google search on IEC62368-1, it says the the IEC62368-1 replaces  IEC60950-1. I have IEC60950-1.

I have the AC power main input and one high voltage output plus other small voltage input ouputs.  I have to decide on how high I should limit the high voltage output and what kind of warning symbols I should put.

The product is to be sold to physicists.

I cannot say much about equipment that falls under IEC61010. I've skimmed through it once or twice and just a few moments ago. There seems to be quite a bit of guidance in Section 5: "Marking and Documentation" and Section 6: "Protection against electric shock". I'm looking at a version from 2004.

For example:

Quote
6.6.2 TERMINALS for external circuits
TERMINALS which receive a charge from an internal capacitor shall not be HAZARDOUS LIVE 10s after interruption of the supply.

TERMINALS which are energized from the interior, with HAZARDOUS LIVE voltage exceeding 1 kV r.m.s. or 1.5 kV d.c., or with floating voltage exceeding 1 kV r.m.s. or 1.5 kV d.c., shall not be ACCESSIBLE. Equipment with such TERMINALS shall be designed so that an ACCESSIBLE HAZARDOUS LIVE voltage is not present when connectors are not mated, or shall be marked with symbol 12 of Table 1 (see 5.2) to warn the OPERATOR of the possible presence of an ACCESSIBLE HAZARDOUS LIVE voltage.

Unmated measuring TERMINALS which are HAZARDOUS LIVE when the maximum RATED voltage is applied to the TERMINAL shall not be ACCESSIBLE.

It seems, in general, that the requirements surrounding laboratory equipment are a little more lax based on the operators being informed and knowledgeable. With consumer equipment, you basically can't trust anyone to read a manual and probably can't trust anyone to comprehend a marking.

Regarding IEC60950-1 vs. IEC62368-1, although the latter supersedes the first, the whole idea of mitigating risk with respect to energy sources/energy levels is new to IEC62368-1. So, you won't really find an equivalent discussion in IEC60950-1, as far as I remember. At any rate, the approaches used for consumer "ITE" equipment safety (IEC62368-1) is generally quite conservative, and it's a good general reference document. But, IEC61010 definitely has the final say.
 


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