Film-Tech Forum ARCHIVE: Grounding Issues with some Smart Products

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Posted by Gordon McLeod (Member # 33) on 06-10-2005, 12:56 PM:

We had an ETL testing done on the racks for a new installation and since the SMART equipment didn't have a CSA or ETL approval they had to be tested independently by a testing authority including a hipot test
The inspector connected the ground of the hipot tester to the ears of the chassis and tested the line and neutral ends of the power cord all was fine till he accidentaly touched the ground plug and instead of a snap there was nothing
The ground pin was not bonded to the chassis
On opening the TCX624 we found that contrary to the NEC the ground wire of the power cord was not connected to the chassis but to a trace on the PCB with a location for a link to connect to chassis. This link was missing and when soldered in there was still no continuity to the chassis due to the epoxy paint on the stand offs that contacted the solder pad on the PCB nor did it connect to the front pannel that has a power switch and the ears that bond it to the rack

At least in Canada any electrical device must have the ground wire of the power cord terminate to the chassis within 3/4" of the entry point also if there is a power switch on a panel it must be bonded with a ground wire to this point
A link that can seperate the signal ground is allowed but definetly nothing like this
Due to this every device in all the racks had to be stripped out opened for individual inspection costing 2 man days of labour and the time for the inspector
I doubt that this is allowed in the US for a UL approved shop?
Any one else have had issues with product grounding

Posted by Gordon Bachlund (Member # 124) on 06-10-2005, 01:53 PM:

Gordon, as we both know all too well, grounding is an important life and fire safety issue. Accordingly, it is always wise to insist that all components bought in the US bear the UL label, as such labeling ensures that the design and manufacture of the equipment conforms to UL requirements, including proper bonding and grounding.

Did the Smart equipment you installed bear the UL label? If so, and these defects were as observed, UL should be notified of the glitch so they can take corrective action with the manufacturer. If not, I would question why the equipment was purchased at all.

In today’s market, much electronic equipment is imported, either as completed components or as parts for final assembly in the US. This situation can lead to the sort of problem that you experienced.

It is inexcusable that a few dollars saved at the manufacturer’s end wound up costing you many dollars in the field. [Mad]

Posted by Gordon McLeod (Member # 33) on 06-10-2005, 04:12 PM:

None of the products were UL CE or ETC certified
In Canada any electrical device connected to th power system by any means must bear a CSA approval or a private approved testing agencies label of compliance with CSA requirements (Hydro Special Inspection, ETL ,)
UL is not recongnized but ULC can do independent testing and labeling to CSA standards
Just like all digital equipment must have a CRTC approval (just like in the US it must have a FCC compliance for noise emmisions)

Posted by Louis Bornwasser (Member # 3063) on 06-10-2005, 04:15 PM:

UL or its generic equal) is required by law in most U>S> states.

Another gotcha......open backed racks are illegal to power up in most larger cities in the US.

Louis

Posted by Richard Fowler (Member # 893) on 06-10-2005, 06:46 PM:

One circuit we worked with paid less insurance premiums by switching to enclosed racks.. the cost savings where paid within a year. [Cool]

One circuit in Brazil had a rule that if any non-tech opened a rack, they where canned....their locations had less sound problems and missing hardware [Wink]

Posted by Mark Gulbrandsen (Member # 72) on 06-10-2005, 10:30 PM:

So Gord,
What has Smart said about all this. Are they ignoring it or taking it seriously, modifing all existing units and production, and also reimbursing you and the chain for lost revenue and for your labor expenses..... More than the actual compliance the Smart making good on a bum product is what really matters the most.

Mark

Posted by John Walsh (Member # 168) on 06-11-2005, 07:28 AM:

I also had some equipment (data switching equipment) tested in 1995 at an ETL lab in Mass (they were Inchscape then.) The grounding requirements were similar. The grounding stud size had to be at least a #10; a nut went on the stud first, then internal tooth star washer, ring lug to AC cord, (must be first on stud and fork lugs were not allowed) nut; repeat for each additional wire. The paint had to be masked and the stud marked with the ground symbol (either by silkscreen or stamped in the metal.)

Posted by Frank Angel (Member # 248) on 06-12-2005, 06:51 AM:

quote: Gordon Bachlund
Gordon, as we both know all too well, grounding is an important life and fire safety issue. Accordingly, it is always wise to insist that all components bought in the US bear the UL label, as such labeling ensures that the design and manufacture of the equipment conforms to UL requirements, including proper bonding and grounding.

Let me tell you a little about that UL Approved label. It was on all the UPS and the surge protector strips we had, all of which were from reputable manufacturers -- Smart, Tripplite, and others. In our theatre complex, Con Ed (our electric company) supplies unusually high voltage -- we have monitors on the mains into the racks that only rarely read below 125v and most times 128v to 132v. That's high. But here's the dirty little secret about surge protector circuits -- they age. And the higher number and the severity of the spikes they suppress, will make them age faster of slower. But not matter, they always age and as they do so, the clamping voltage threshold drops. Since our voltage is generally high, sooner or later the clamping voltage threshold and the line voltage input cross. At that point the surge protection circuit goes into clamp mode -- constantly. Then comes a real spike which causes the innards of the surge protector to freakin burst into flames. I kid you not. On some, fire actually shot out of the edison sockets -- one of our older secretaries nearly fainted and had heart palpitations when the one right on her desk hissed and shot flames and smoke out the sockets, blistering one of the line cords that was plugged into it. Given where most of those surge protectors wind up living -- under desks, on desks with combustible crap all around them, this is a combination for disaster.

One of our largest UPS units with a huge battery -- something like 50 pounds -- burst into flames and even after it was unplugged and doused with a fire extinguisher, the flames extinguished for a few seconds and then it started right back up again. i.e., self-fueling and not about to be extinguished by normal means. It continued to burn and spew noxious fumes as we tried to drag it by its cord out of the building. After three of the UPS and four of the surge suppressors "flamed out" as we call it, I went to every suppressor strip and opened them up to find all of them had charred crispy critter components -- some so bad that the disc caps had their encasement material disintegrated into black charcoal. These were all UL Approved....to insure safety and prevent FIRE....lucky for us, huh?!!

I later discovered that, yes indeed, the surge protector strips and the UPS UL spec had a flaw -- that's what they call a piece of hardware that can burst into flames without warning....a flaw). Underwriters Laboratory has since revised their specs on surge protectors to include some kind of thermistor or something called a MOV that will sense overheating and protect the circuit, or so I'm told. Thing is, UL they never recalled the millions of units WITHOUT that super important, potentially life-saving component, so you never know when you buy one of these innocent-looking surge protectors strips, if it will burst into flames on you or one that follows the "improved" UL Approval spec.

So much for the UL Approved label.

Posted by Steve Guttag (Member # 268) on 06-12-2005, 09:47 AM:

Frank,

The MOV is generally the thing that bursts into flames, not capacitors (the MOVs look like capacitors though...they are disc shaped typcially). MOV (Metal Oxide Varistor) will clamp the line when its voltage is reached...and like you said, degrade with each "hit" and will evenutally fail in dramatic form (though it isn't a matter of time so much as how many "hits".

The current hot trend in upper end surge supression is "series mode" surge supressors that do not use MOVs but a network that presents a high resistance to the surge so virtually no current flows. SURGE-X is a popular brand of such units.

In the case of Tripplite, Power conditioner is more like what you need in your situation (e.g. LCR-2400). It has a mulit tap transformer that will supply 115 - 125 regardless of in coming so your equipment will not be seeing your 130+ voltage...in addition to the surge supression (MOV based).

As to UL...they like ETL and other labs are not the only labs and they are not perfect but life is much safer with them. They approved Christie's AW-3 without any fuses or circuit breakers in the platter which can and has had complete wiring harness melt downs without any protection.

The problem with one recognized testing agency is that they tend to rip off the manufacturer (and the end user). In the states, UL had a virtual lock on safety certifications. California has their own that is recognized in California but not in every state. Fortunately, ETL came along to offer competition and competitive pricing. ETL is recognized in every state in the US, that I'm aware of.

Posted by Mark Gulbrandsen (Member # 72) on 06-12-2005, 02:14 PM:

quote: Steve Guttag
They approved Christie's AW-3 without any fuses or circuit breakers in the platter which can and has had complete wiring harness melt downs without any protection.

Actually most transformers used in AW-3's with the exception of some older ones all have thermal fuses built into the transformer. These versions eliminate the melt down hazard and no other transformers should be substitiuted in an AW-3. Replace it only with the factory original part to ensure continued safety.

Mark

MArk

Posted by Bruce Hansen (Member # 281) on 06-14-2005, 05:59 PM:

Frank,
You may want to call Con Ed, they may have the wrong tap connected on a transformer somewhere. When the voltage is high, some devices will draw more current. Being summer, Con Ed does not want this extra draw on their system.

Posted by Mark Gulbrandsen (Member # 72) on 06-14-2005, 07:16 PM:

A theatre here in SLC had that high line voltage problem but Utah Power was able to re-set some taps on their feeder to get it to a more realistic maximum level which I think is now 121 on the high end of things. They used to blow up strong switchers at the rate of about 2 per month [evil]

until the voltage was dropped slightly. They even had a QSC amp act like a flame throwner once when it blew [evil]

.

Mark

Posted by Don Goulart (Member # 3189) on 08-03-2005, 02:59 PM:

Gordon,

This is my first post at this site. I'm sorry no one answered you about your question. I've forwarded your concerns regarding the specific electrical standards to Norm. Our processors have no voltage higher than +/- 20vDC. Our power supplies do have a grounding stud that takes the AC ground wire and connects it to the chassis. If you have any further questions or need anything regarding SMART/Panastereo please let me know.

Don Goulart

service@smartdev.com