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[Russell Ault]

You can be sure that if the manufacturer didn't NEED to use 3 wire, they would have used 2. {...}

Is this a code requirement? Given how ubiquitous grounding connectors (whether IEC C13/C14 or the various PowerCON flavours) are in our industry, I wouldn't be shocked if it turned out that some piece of gear out there has a three-prong inlet but leaves the ground N/C (or—perhaps more likely—gear with a design that would have been perfectly happy without a safety ground but that makes use of it anyway because the "industry 'standard'" connector provides it). That's not an excuse for disconnecting a safety ground, to be clear, but I am curious whether the presence of a ground at the connector necessitates its use?

-Russ

[John Roberts {JR}]

Is this a code requirement? Given how ubiquitous grounding connectors (whether IEC C13/C14 or the various PowerCON flavours) are in our industry, I wouldn't be shocked if it turned out that some piece of gear out there has a three-prong inlet but leaves the ground N/C (or—perhaps more likely—gear with a design that would have been perfectly happy without a safety ground but that makes use of it anyway because the "industry 'standard'" connector provides it). That's not an excuse for disconnecting a safety ground, to be clear, but I am curious whether the presence of a ground at the connector necessitates its use?

-Russ

Two conductor line cord products a wired to different internal insulation standards (like Class II, double insulated mains connected wiring). You may get some idea by reading the owner's  manual or from markings on the rear panel.

I expect 3 conductor IEC line cord jacks are more expensive than 2 conductor jacks.  I would not expect a 2 conductor IEC line cord to fit into a 3 conductor IEC jack.

Of course if the SKUs are not safety agency approved who knows?

JR

[Brian Jojade]

Is this a code requirement? Given how ubiquitous grounding connectors (whether IEC C13/C14 or the various PowerCON flavours) are in our industry, I wouldn't be shocked if it turned out that some piece of gear out there has a three-prong inlet but leaves the ground N/C (or—perhaps more likely—gear with a design that would have been perfectly happy without a safety ground but that makes use of it anyway because the "industry 'standard'" connector provides it). That's not an excuse for disconnecting a safety ground, to be clear, but I am curious whether the presence of a ground at the connector necessitates its use?

-Russ

Delving into the internal engineering of a piece of equipment is beyond the pay grade of most on these forums.

General rule is if it's got a grounding connector, you should be using it.

Safety ground is just that. Safety ground.  Pretty much EVERY piece of equipment would work without the safety ground connected. It's just potentially less safe.

Is there a risk of lights hanging on a T-Bar connected via wireless DMX? No, probably not.  But it's not a good idea to take that risk.

[JohnPinchin]

I have a few of those pars, to keep the power simple I daisy chain them as they have an iec in and out socket.  I would think that is an easier and safer way.

[Russell Ault]

Two conductor line cord products a wired to different internal insulation standards (like Class II, double insulated mains connected wiring). You may get some idea by reading the owner's  manual or from markings on the rear panel. {...}

Understood; I'm just curious if there are any Class II double-insulated devices out there with, say, PowerCON connectors (i.e. connectors with a safety ground) and, if so, what they do with the safety ground (if anything).

Delving into the internal engineering of a piece of equipment is beyond the pay grade of most on these forums.

General rule is if it's got a grounding connector, you should be using it.
{...}

Just to be really clear, I agree with both of these statements (hence my "not an excuse for disconnecting a safety ground" statement; even if the the ground is left N/C internally I would still expect to see it cabled correctly).

-Russ

[Scott Holtzman]

Understood; I'm just curious if there are any Class II double-insulated devices out there with, say, PowerCON connectors (i.e. connectors with a safety ground) and, if so, what they do with the safety ground (if anything).

Just to be really clear, I agree with both of these statements (hence my "not an excuse for disconnecting a safety ground" statement; even if the the ground is left N/C internally I would still expect to see it cabled correctly).

-Russ

If the power was the only connection to the device I might see a case to be made, however with the data connection we are risking fault current exiting the data connector due to a lack of a signal ground.


that doesn't work for me.

[Daniel Levi]

There will be things with a 3 prong inlet where the earth connection is not used if the higher current requirement is needed compared to a "figure-8" connector or polarity of the connector is important but that's fairly uncommon, of course there is a two prong "kettle" type connector as some XBOX 360's used which is the correct connector on an un-earthed device to remove any earthing confusion.
Now the reason why some devices will have an earth connection but have no exposed metal parts is that it's used for radio frequency emission reduction, a lot of 3 pin laptop chargers will be like this and is called a "functional earth" and is denoted on the device by an earth symbol with a half moon/semi-circle over it.
It's an important thing to note in portable appliance testing as you could potentially fail a device for no earth continuity when it's not supposed to have any earth continuity.

[John Roberts {JR}]

Understood; I'm just curious if there are any Class II double-insulated devices out there with, say, PowerCON connectors (i.e. connectors with a safety ground) and, if so, what they do with the safety ground (if anything).



-Russ

I have no idea about current industry practices in the lighting industry.

Class II is a higher standard of mains wiring (double) insulation to provide adequate human safety when using 2 conductor line cords. There is no reason that Class II wiring could not be used with a 3 conductor line cord connector. I can imagine OEM switching power supplies that are Class II insulated used inside 3 conductor line cord SKUs.

I would ASSume that a 3 conductor line cord would bond safety ground to the metal chassis. of course if there is no metal chassis, YMMV. 

Caveat this is pure specualtion on my part and I do not have first hand information.

JR

[Frank Koenig]

First, I’ll pile on and say if the plug has three prongs, use them.

But here’s my more nuanced issue. Many pieces of utilization equipment sold to consumers have two-wire cords and are very clearly NOT double-insulated. Portable lighting devices (lamps, in common parlance) often have a piece of shitty zip-cord threading its way through a metal tube that anyone can touch. All it takes is for the insulation on the hot side of the zip-cord to chafe through and touch the metal parts and the whole fixture is hot, ready for someone to touch it and anything grounded. If they’re lucky it’s plugged into a working GFCI. If not, they’re gonna jump – or worse.

This bothered me for years. I once asked a fellow at Underwriter’s Laboratories (UL) about this and got the following answer. Electrical safety standards are to a large extent driven by accident statistics. Things that almost never kill people, like living room lamps, are allowed to get away with fundamentally unsafe construction – no doubt lobbied for by the manufacturers who want to minimize cost. Things like hair-dryers that, apparently, kill people all the time are required to have GFCIs built into the plug. Things like line-powered portable tools fall into the middle ground where they either need to meet the requirements of double-insulation or have three-wire cords.

It’s a lot like cars, airplanes or many other things. The regs follow the dead bodies.

--Frank

[Steve-White]

First, I’ll pile on and say if the plug has three prongs, use them.

But here’s my more nuanced issue. Many pieces of utilization equipment sold to consumers have two-wire cords and are very clearly NOT double-insulated. Portable lighting devices (lamps, in common parlance) often have a piece of shitty zip-cord threading its way through a metal tube that anyone can touch. All it takes is for the insulation on the hot side of the zip-cord to chafe through and touch the metal parts and the whole fixture is hot, ready for someone to touch it and anything grounded. If they’re lucky it’s plugged into a working GFCI. If not, they’re gonna jump – or worse.

This bothered me for years. I once asked a fellow at Underwriter’s Laboratories (UL) about this and got the following answer. Electrical safety standards are to a large extent driven by accident statistics. Things that almost never kill people, like living room lamps, are allowed to get away with fundamentally unsafe construction – no doubt lobbied for by the manufacturers who want to minimize cost. Things like hair-dryers that, apparently, kill people all the time are required to have GFCIs built into the plug. Things like line-powered portable tools fall into the middle ground where they either need to meet the requirements of double-insulation or have three-wire cords.

It’s a lot like cars, airplanes or many other things. The regs follow the dead bodies.

--Frank

"The regs follow the dead bodies."

Unfortunately, that's truth Frank - well stated.  I see it all the time in the racing community - somebody has to die first.

On the flip side are things like gasoline cans.  After a big winter storm in the east coast circa 10 years ago, many bought generators, had no clue as to safe operation, so there were fires.  Government stepped in and fixed everything.  Now we have gasoline cans that are in large part useless and at best very difficult to use.  Fortunately, the racers haven't screwed that up so you can still buy racing fuel cans that work.

[ProSoundWeb Community]