Huge SAFETY CONCERN, DPST switch used HALF mains and HALF DC....

[tpowell1830]

OK everyone as the OP i have give a final report upon what had to happen. Based on the fact that there was a possibility that the way 12Vdc and Line of 230Vac was being switched on the same switch (and the fact the PINS of the XLR-4 male socket could be easily touched, then it was decided to mod each light.

The fact i'd noticed a questionable situation of a possible safety issue kind of follows under the Laws in this Country that i needed to do something to circumvent any chance of an accident resulting in an electrocution. I could have zipped the whole unit back up and put it out to be used by my fellow staff, ( the camera News Crews at the station i'm employed at as a Qualified Registered Maint Engineer) but under OSH and new Health & Safety rules let alone the Govt. section of the Electrical Workers Registration Board, if anything actually happened i'd become a "port of call" in an inquiry for sure.

So the Mains is now not permanently attached but connectable via a Neutrik mains plug/socket... PowerCon series connector. The original switch breaks L and A only. The Earth off the Powercon connect goes directly to chassis via a crimped spade terminal and held under a wrinkle shakeproof washer with a 3mm screw and nut. The XLR-4 connector with the 12Vdc now has it's own dc switch in the +ve line.

The cost to doing the mod if properly charged and each minute of labour checked would send a company accountant to DRINK !

The only reason it was done is to comply with the incredibly strict considerations of this country's current newly applied Health and Safety Act of which all businesses are taking the option of we'd best do "X" or else....


Thanks for all the input from all who took time to post....

Okay, have been listening to the arguments about whether this is true or that is true, but what sticks out is the original question, and I paraphrase: "Is this configuration safe?"

My answer would simply be "I don't know because I do not have ample information about this system, other than a picture."

With that said, the thought that I have about changing a design of electrical wiring and components in a device that will be used and handled by humans is that, if I change that design and modify the wiring and/or components, the liability of failure now falls on me.

My solution would be to replace all of the units with an acceptable unit that has been checked for all of the above safety concerns. This way, the safety questions and concerns are met and I have not refocused the liability on myself or my team.

Just my 2 cents...

[CopperCone]

I saw fucked up rocker switches (from DC) on an entire product line!

[vk6zgo]

OK everyone as the OP i have give a final report upon what had to happen. Based on the fact that there was a possibility that the way 12Vdc and Line of 230Vac was being switched on the same switch (and the fact the PINS of the XLR-4 male socket could be easily touched, then it was decided to mod each light.

The fact i'd noticed a questionable situation of a possible safety issue kind of follows under the Laws in this Country that i needed to do something to circumvent any chance of an accident resulting in an electrocution. I could have zipped the whole unit back up and put it out to be used by my fellow staff, ( the camera News Crews at the station i'm employed at as a Qualified Registered Maint Engineer) but under OSH and new Health & Safety rules let alone the Govt. section of the Electrical Workers Registration Board, if anything actually happened i'd become a "port of call" in an inquiry for sure.

So the Mains is now not permanently attached but connectable via a Neutrik mains plug/socket... PowerCon series connector. The original switch breaks L and A only. The Earth off the Powercon connect goes directly to chassis via a crimped spade terminal and held under a wrinkle shakeproof washer with a 3mm screw and nut. The XLR-4 connector with the 12Vdc now has it's own dc switch in the +ve line.

The cost to doing the mod if properly charged and each minute of labour checked would send a company accountant to DRINK !

The only reason it was done is to comply with the incredibly strict considerations of this country's current newly applied Health and Safety Act of which all businesses are taking the option of we'd best do "X" or else....


Thanks for all the input from all who took time to post....

Okay, have been listening to the arguments about whether this is true or that is true, but what sticks out is the original question, and I paraphrase: "Is this configuration safe?"

My answer would simply be "I don't know because I do not have ample information about this system, other than a picture."

With that said, the thought that I have about changing a design of electrical wiring and components in a device that will be used and handled by humans is that, if I change that design and modify the wiring and/or components, the liability of failure now falls on me.

My solution would be to replace all of the units with an acceptable unit that has been checked for all of the above safety concerns. This way, the safety questions and concerns are met and I have not refocused the liability on myself or my team.

Just my 2 cents...

You obviously have never worked in a TV Studio!
When Production people want stuff, they "want it yesterday"!!

Virtually all this sort of stuff comes from "the other side of the world", made by manufacturers who "take their own good time" about things, so most times, if there is a problem the only practical thing is to fix it locally.

[rs20]

Okay, have been listening to the arguments about whether this is true or that is true, but what sticks out is the original question, and I paraphrase: "Is this configuration safe?"

My answer would simply be "I don't know because I do not have ample information about this system, other than a picture."

This is a question of safety, so "I don't know" automatically translates to "no" for all intents and purposes.

The reason the debate has run so long on what seems like a simple question is because it's actually a dangerously vague question which hides two specific, easily answerable questions:
- "Is it acceptable to do this/does the manufacturer guarantee that this is acceptable?"
- "Is it reasonable to expect that harm couldn't typically be done?"

The answer to the first question is fairly clearly "no", and plenty of reasonable evidence that the answer to the second is "yes" has been provided.

What's disturbing to me is that people have been answering the second question as if it's a valid answer to the first. Such an attitude shows a severe disrespect for human life, and I hope it's not coming from practicing engineers. Safety is not a field where you get to speculate on what's "almost certainly" true.

[Gregg]

There seems to be lots of room in the fixture to replace the existing switch with a standard industrial 22mm switch.  They come in multiple configurations like 2 position or 3 position and the actual switching modules come in NO and NC.  Multiple switching modules can be stacked making your circuits totally isolated on a single switch. 

[SeanB]

Many of us have heard or, or experienced a Class X cap failing (RIFA), but how many have had a double pole rocker switch fail shorted, or even arc between the poles when used at it's nominal rating?  It has to be a spectacularly rare event, if it has happened at all.

If someone smashes the switch then they could directly expose the live  connection, a far more serious problem than possible short to the other pole, so that's another irrelevancy.  As previously mentioned, this isn't even a consumer device.

Those switches regularly fail, and I have had them blow up as well when moisture provides a bridge, or the little springs inside decide to break and the floaty bits short out the 2 sides. The plastic also degrades with time, and as the inner side often is made from recycled or mixed content ( the bits that were either rejects repelletised, or the recycled plastic of mixed colour from some random seller) as it is not visible. Stove repairers are very well aware of how poor these switches are, they are a common failure on many things, either popping the top off exposing the live inner parts, or simply shorting, or even just falling apart with time. Hard to tell the quality unless you have a well known manufacturers unit, and that could be replaced by anybody with a non correct part for either cost cutting, or as a service part, without anybody being the wiser, as the cutout and pin outs are a common industrial size.

I agree on the use of a 22.5mm industrial control panel button and using some industrial contact assemblies, as those are both robust, double acting fail safe contacts and each module is isolated from each other to withstand 2.5kV for 30 seconds insulation test, just place 4 blocks so the wear is kept the same, even if one block is never going to be used, and so that the mains section is separated physically from the 12V side by a barrier strip.