How good is ETL safety certification?

In the late 80's law was passed to allow other than specification writing agencies to do testing to specifications such as UL

See

for more details.

Of course one really has to know what specifications the product is being certified to.

There are a multitude of UL and IEC specifications that cover different products and product applications.

Dan

-- Dan Hollands

1120 S Creek Dr Webster NY 14580

ETL certification is valid. Whether to use UL or CSA or ETL is a matter of cost, schedule, customer service, and factory location (proximity of facotry to service provider affects FUS [follow-up service] costs). ETL would require samples and documentation. CE is just a mark, not an organization. ETL (like UL and many others) can provide services permitting usage of the CE mark. Your meter rated at 500V but having 250V fuses is not odd. These fuses are for overcurrent protection, and 250V is the highest nominal value for commonly available replacement fuses. Coffee makers require flame retardant plastic (94-V0 or V1). Standard is EN60335? Thermostat versus two thermal fuses is an individual manufacturer's design consideration. Either of these or other protection methods are valid as long as all of these test in the standard(s) can be met.

Is there a chance that a fuse with a too low a voltage rating can explode violently enough to pierce through the case? I noticed that the 600V fuse in a Fluke meter was enclosed in woven fabric, possibly for such a rupture.

I thought a coffee maker would be required to have a backup means of shutting off the current in case the bimetal thermostat failed because back in the 1970s or 1980s there was a big lawsuit against GE when thermostats in some of its coffee makers failed and caused fires.

are

is

design

Back up>>>> your joking. I have had it with most of the coffee makers on the market. I plug them in in the morning and unplug them when done. Tired of the crappy el-cheapo stuff. If it aint plugged in it certainly will not hurt anything.

are

is

design

Back up>>>> your joking. I have had it with most of the coffee makers on the market. I plug them in in the morning and unplug them when done. Tired of the crappy el-cheapo stuff. If it aint plugged in it certainly will not hurt anything.

I've had the delightful experience (~1980) of being in a computer lab next to an office where someone left one of those things going, when they left for the day. An unforgettable experience...by the time we could smell the smoke in the lab, the office was completely engulfed in flames.

Are they really any safer, now? Seeing the efforts big business has been making to remove government oversight where it can, I'm not terribly confident about that.

UL isn't government. From my experience (mostly residential lighting equipment), I haven't noticed any relaxation of standards for fire or electrical safety. If anytthing, It has been just the opposite. Competition appears to be good for UL. Manufacturers have options including ETL and CSA (Canadian Standards Association) and others so there are alternatives. That helps costs and speed of testing. They all test to the same standards. Some lighting equipment standards are now tri-national (US, Canada and Mexico).

TKM

: > I've had the delightful experience (~1980) of being in a computer lab : > next to an office where someone left one of those things going, when : > they left for the day. An unforgettable experience...by the time we : > could smell the smoke in the lab, the office was completely engulfed : > in flames. : >

: > Are they really any safer, now? Seeing the efforts big business has : > been making to remove government oversight where it can, I'm not : > terribly confident about that. : : UL isn't government.

Never said they were. UL doesn't make the laws, you know? What I'm saying, is that big business always has, and always will try to make an endrun around the rules, if it seems profitable, especially if it looks like no one will ever catch them.

: From my experience (mostly residential lighting : equipment), I haven't noticed any relaxation of standards for fire or : electrical safety. If anytthing, It has been just the opposite. : Competition appears to be good for UL. Manufacturers have options including : ETL and CSA (Canadian Standards Association) and others so there are : alternatives. That helps costs and speed of testing. They all test to the : same standards. Some lighting equipment standards are now tri-national (US, : Canada and Mexico).

Even if UL or some other agency has tested the products, there is still room for poor QA...and some people cheat, when it comes to keeping to the standards, too. Just because something you're familiar with doesn't appear to have any problems, doesn't mean there aren't any, either.

Of course. But there are data. Injuries and deaths from electrical shock and fires for one. These have remained just about constant even though the population has increased and has become less aware of electrical hazards (my view). The CPSC opened an investigation of electrical/lighting fires last year and is even paying a $50 "bounty" to fire departments to file reports. Nothing significant so far.

What I see as the main problem at the moment is fake and counterfeited UL (and other) marks placed on products, mostly imported, that haven't been inspected or built to standards. Major manufacturers are paying extra to CSA, for example, to do "dock" inspections overseas to ensure that what's in the container is what they ordered including proper standards marking.

But where does the fake stuff end up -- on the internet, in "dollar" stores? I don't know.

TKM

Many 600 volt fuses are available. The meter I use has 600 volt fuses and they are readily available in the area I live.

Are 600V fuses that are no more than 3/4" long? That's all the room there is for a fuse in my meter.

How do you rate a fuse for voltage? It would be a peculiar design that would flash over between terminals even at 500 volts.

--
*There are two sides to every divorce: Yours and shit head's*

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

Really? Then try a 32 volt automotive fuse at 500 volts. PS, make sure you can pull the plug or kill the main braker before you grab the fire extingisher.

--
Been there, Done that, I've got my DD214 to prove it.

Michael A. Terrell
Central Florida

Really? Even an 1 1/4" 'automotive' fuse?

--
*Why is it considered necessary to screw down the lid of a coffin?

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

"Voltage Rating The maximum voltage at which a fuse is designed to operate. Exceeding the voltage rating of a fuse impairs its ability to clear an overload or short circuit safely. Fuse can be used at any voltage below the fuse voltage rating; a 250V fuse can be used in 125V circuits. Voltage ratings are assumed to be for AC unless specifically labeled as DC."

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Cheers! Rich

The US old style glass tube automotive fuses when burned open won't flash over at 500 volts. But if connected to a 500 volt circuit, when they open the melting metal will likely vaporize and the conductive plasma created will continue the conduction. The energy released would likely cause the fuse to explode - not acceptable for most users. On high available current circuits the plasma could go end to end causing conduction for a relatively long period. The arc can vaporize more metal feeding the plasma. This can cause a large explosion with flying shrapnel.

US fuses have not only a voltage rating but a rating for the maximum current the fuse will interrupt. If the circuit has an available fault current higher than the fuse interrupt rating the fuse can also explode, even though the fuse is used within its voltage rating. I expect you have the same thing over the pond.

Multimeters are rated for where in a power circuit they can be used, like downstream from a panel (lower avalilable fault current) or on service wires (high available fault current). This is based on the design as in the paragraph above. I believe this is an IEC standard.

bud--

More particularly related to voltage: When a fuse opens there will be an arc. The arc will have a voltage across it. 32 volts will not support a very long arc. 500 volts will suport a much longer arc and will be a lot harder to extinguish. As fuse material is vaporized (as opposed to just ionized air) the resistance of the arc will go down and an arc with a voltage drop of 500 volts across it will increase and be even harder to extinguish.

The interrupting capacity of a typical 1.25" Fast-Acting 3AG fuse at

250V is MUCH lower than at 125VAC. They will interrupt 10kA at 125V, but only more like THIRTY-FIVE amps at 250V. Check out the data sheets.

Put them in a situation where they can see thousands of amperes fault current @240V and they can and often do EXPLODE, rupturing the glass and sending fragments everywhere.

Of course the 20mm types are worse again.

That's why Fluke multimeters use a much larger fuse.

During failure of the 3AG type fuses, the melted metal ionizes inside the fuse and allows an arc to form directly from one end cap to the other, which has very low impedance (low voltage drop, but lots of watts for such a small enclosed space).

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

All fuses (of any qulaity) are rated for a maximum voltage. Also not usualy in big letters they will have a maximum current they can inturrupt. While looking at the physical size of them, they all look the same. I don't know what the differance is in them, but there must be. I was in a class put on by one of the fuse makers. They said that at one time one of the selling points for so many differant kinds of fuses it that they are made for a specific purpose. Now they have reversed the thinking (selling point) that one fuse will replace many fuses that are similar.

It is really interisting to watch the Fluke meter film on using the wrong fuse in a circuit. Nice demonstration of what can hapen if you hook you meter across the circuit while in a current or ohm range when you really mean to measuer the voltage.

At work I look in the cabinet with fuses and see about 10 differant fuses that are almost the same size and ratings. Some will have slightly differant tips on them so you can not use them in the some fuse holders. Really bad to have to stock so many differant kinds.