i cannot understand how most surge strips can be safe. p

[rong111]

hi all,
yesterday i took apart 7 different surge outlet strips. all under $25(maybe this is the problem?).
all different models, all diferent manufacturers.
what i found:
all of them tie ground to neutral. this is the entire principle on which they work. i always thought we do not tie ground to neutral past the service entrance in residential wiring? this was my main area of concern on these.

second: soldering on all of them must have been done by a monkey. the connections (all but one) are solid. but, way too much flux and way too hot of a solder. obviously they had speed of assembly in mind here.

third: two of them use backstab recepts as the outlets! the ones that are rated #12 AND #14 even!
of these, one of them has the ground completely unconnected on the recepts, as the neutral now carries the full ground potential.

fourth: 3 of them do not incorporate a thermal fuse. so when the mov's overheat, at some point there could be potential melting of the housing and subsequent ignition of surrounding materials.
mov's can and do reach over 300f. at their limit.

i am not trying to be a wise guy here. i cannot understand how these can protect expensive connected equipment. i'd think they are more likely to destroy the equipment!
please explain what i am not understanding here. there has got to be some reason these are safe that i am overlooking, right?

i am not naming any brands here so no one gets upset. i think the real problem may be the price point of the units i examined. but still, how does ul pass these? fyi: none of them are older than 1999.


thank you,
ron g.

 

[karl riley]

Re: i cannot understand how most surge strips can be safe. p

Ron, I hope you get some responses here. This is news to me, and I am getting out my screwdriver right now.

Karl

 

[iwire]

Re: i cannot understand how most surge strips can be safe. p

I imagine when you say the neutral is connected to ground that the connection is not direct, but through some electronics.


Bob

 

[rong111]

Re: i cannot understand how most surge strips can be safe. p

in only 2 of them the neutral was tied to the ground through the movs simply soldered on the end of a wire. like this, white wire soldered to one lead on a mov other lead of same mov soldered to the lead on the next mov etc. last mov lead solderd to green wire. the movs always have continuity so this is practicly the same as a direct tie. the others have the green and white both soldered to the neutral side of the rail!
i hear (some) very new ones have a thermal fuse by the movs to prevent the inevitable overheating from a large (or several small) surges. well these are not for mission criticle applications since once they encounter a surge the thermal fuse opens and they no longer conduct electricty!
furthermore all but one of these(the one i mentioned was backstabed) do not even use recepts! they use a copper "rail" that is continuous and accepts each plug in series.
i encourage everyone to take at least one of these apart. what i found in my 7 is really scarry to me. i hope brand new ones(2003?) are better built. or more expensive ones are better built. still price should have no bearing on their safety if ul stamps them. i can't understand this. i mean the neutral tied to the ground is just the tip of the iceberg here. the workmanship on these (made quickly in china) is real real poor. all of them seem to be made in china. i have nothing against china except that their products usually tend not to meet what we expect in the us.
anyways i am sure someone here will get around to posting that this is exactly the principle in which these things work. i know this already.
they dump a surge to the earth. that is why they are tied. the problem is they have now tied your whole system! plug a stupid radio shack "outlet tester" into one of these and see what is says! now plug it in anywhere on that branch and see what happens!
what i want to know is there has to be some explanation as to why these are safe. otherwise i do not see how the nec or ul can allow these.
they are listed as portable temporary power tap. but do not meet that actual specification as the leads are tied! is it just a way for them to list an unsafe product? i hope someone here can assure me these are safe otherwise i am plugging everything right in the wall!

also, surges of large proportion are rare on 120v 1 phase service. the real killer of electronic appliances is sags/brownouts. where voltage can drop as low as 87 volts then hit 130 before returning to 115. this fluctuation is what kills appliances. now guess what? i am going to take apart 2 ups's to see how well these are constructed! one cost $119 one cost $199 both considered cheap. but as i said price should have no bearing on safe workmanship if they are listed!

i think the bottom line here is all of us that have a nice television/computer/stereo need to get a $1,000 ups. i hope i am wrong about this!

ron g.

 

[rong111]

Re: i cannot understand how most surge strips can be safe. p

i just noticed that according to some manufacturers ul has revised listing 1449(surge suppressor qualification) twice. once in 1998 and once in 2001. although i cannot find reference of this on ul's site. i will get a new strip later today and take it apart. i am hoping the new ones seem a lot safer. my oldest one is dated early 1999 but may have passed by the 1998 ruling. anyways even if yours are all well built it is good to replace them every 3-5 years as mov's are a sacrificial part. also, if the light is on on your surge strip that does NOT mean that the mov's are intact on most models. it simply means line power is present. even if the led is labled "protected when lit" etc. apparently the new ones have an actual indicator of the protection being present. i will let you all know if the ups's and the new power strip seem any better later tonight.

ron g.

 

[ron]

Re: i cannot understand how most surge strips can be safe. p

The connection of Neutral and Ground through a MOV maybe their attempt at N-G Mode protection. The MOV only conducts (connects) with a high voltage potential.
The second addition of the UL standard requires protection of the MOV's. I'm not sure if that protection with be evident on each unit, as the manufacturer may ahve a wacky way of protection other than a replacable fuse.

 

[dereckbc]

Re: i cannot understand how most surge strips can be safe. p

Ron G, your statement ?the movs always have continuity so this is practically the same as a direct tie? is incorrect. It is called the N-G mode of protection as Ron stated. Imagine if you applied the same logic as the MOV between L-N or L-G, it would be a short circuit. MOV?s are made to conduct at some specified voltage. However there is some leakage, but it is small and insignificant. Without MOV's being connected between points of different potential, you wouldn't have a TVSS. :roll:

UL1499 second edition, was updated to level the playing field for TVSS manufactures. They basically changed the definition of "clamping voltage" to "SVR" (Suppressed Voltage Rating) The UL now test the whole assembled unit with 6 inches of leads beyond the apparatus case. Most manufactures fudged the ratings by only testing the individual modules separately with out leads, rather than as a unit. This allowed them to publish lower than reality clamping voltages. Manufacture also use terms like "amps per phase" and "joules" which mean nothing. UL1499 second clears the air.

I would look at the units and see what standards the TVSS device is designed too and what standards were used to test the unit specifications. The better units will have all these, UL 1449, Second Edition, UL 1283, cUL, ANSI/IEEE C62.41 ? 1991, C62.45 ? 1995, and NEMA LS-1 ? 1992. I can tell you from experience you will not find one for less than $100 with these standards applied.

As for UPS in the price category you mentioned are the stand-by type of units, which offer no protection or voltage regulation, and use approximation of sine wave methods when activated. You have to move up to a line interactive or dual conversion types to get voltage regulation and pure sine wave output.

[ September 14, 2003, 06:41 PM: Message edited by: dereckbc ]

 

[hurk27]

Re: i cannot understand how most surge strips can be safe. p

Dereck
The one pet-peeve I have is the UL requires manufactures of strip surge suppressors to install a thermal fuse ahead of the MOV but manufactures of appliances and electronic equipment don't have to. I hold an Indiana license to do electronic repair and almost all of the manufacture's will have regular fusses after the MOV's so if the equipment gets hit with a long enough surge like the one we had a few month's ago the MOV blows open and the equipment gets trashed,
I know the reason for this, As this is one way for them to see if the equipment has been over voltage or improperly wired. (so they don't have to warranty it)
and of course they get to sell more equipment. but I thought we lived in America where right is might and this sort of thing should not happen. of coarse after I repair the equipment I install a fuse ahead of the MOV to allow it to open the circuit and protect the equipment. I wish there was a way to get UL to mandate the fuse ahead of the MOV as it is required in surge suppressors.
It bothers me when I see the unknowing public getting riped off.

[ September 15, 2003, 01:17 AM: Message edited by: hurk27 ]

 

[Guest]

Re: i cannot understand how most surge strips can be safe. p

Which electronic and electric devices have the fuse after the MOV? Thank you for bringing this to our attention.

 

[rong111]

Re: i cannot understand how most surge strips can be safe. p

ok i have some questions and answers here.

there is up to 40 volts present on the ground on all of these things, so i am thinking it must be connected somehow. that is how all of these work. they take a surge and dump it to the earth. so there has to be a path from l and n to g. but it should remain open untill energized in theory. maybe it has to do with the quality of components used? i get this reading even on an isolated variac. so i know it is not my homes service. like you all stated though the mov's should not complete a circuit untill they are energized. so what is wrong with mine? are they failing because they are so heavily used? my understanding is that a bad mov completely opens, not arcs closed. is up to 40 volts on the ground rail at no load ok on these things? by comparisen i am only likely to find up to 3 or 4 volts at a branch outlet here without one of these present on the branch.

only two of them have a fuse ahead of the mov's none of them have a thermal fuse.
that is why i got the new ones because if a good surge hits the mov and it gets hot enough the plastic housing can melt and ignite carpet etc. not a proplem anymore with ul 1449(2). on the other hand all of the ones i bought including the new ones only meet ul 1449 nothing else. and state nothing about second edition!

i think the thermal fuse is great. only one problem for me here! i need one of these for a mission critcle application and would rather let through a surge then have the circuit open. but still not have mov's overheat on me. what can i get for this?

one of these units actually had the green directly tied to the white. and guess what? this one was NOT ul listed. go figure. the sad thing is the average consumer does not know what they are buying and manufaturers pray on them. the better units seem to have a metal housing forcing them to use actual recepts in them. the plastic ones use continuous stamped metal rails
as the recepts.

the two new strips have better circuit topology and are mounted to pc boards. still being only $18 each the soldering and grade of components is pretty bad.

what i still do not understand is why the radio shack outlet tester(i know it is working) finds a open ground or a ground and neutral tied on all of these?

i had a chance to take apart probably the most expensive surge bar made. it is made in the usa. it does not even use movs! it uses gas expansion tubes as a secondary path to ground on l and n poles. this is great because a gas tube conducts no electricty untill it becomes energized and the electrons are excited. plus a gas tube is no where near as sacrificial as a mov and requires no thermal fuse. i guess you get what you pay for?

now i have one more question please! dereck you just mentioned my ups's do not protect against fast transients. what would i have to spend(approximate) to get a ups that can very quickly clamp on over/under voltage with plenty of headroom and supply 12 amps? i hate to hear what this will cost! can i do it with a 1 phase unit?
i know many that can do this but i cannot afford these for my home. funny thing is that all the manufacturers claim it can clamp on 87 to 130 volts and level to 120 in less than a nanosecond. plus they state they can do this repeatedly. lower than 87 volts is considered a total power loss and they go on full battery. even a $39 unit claims this! how can the manufacturers lie like this?

ok sorry for such a long post
ron g.

 

[rong111]

Re: i cannot understand how most surge strips can be safe. p

i just thought of one more thing.

dereck, you mentioned joules is a nonsense term.
i realize it is misleading in the way manufacturers state that it is an indication of how long a unit will last. on the other hand isnt joules a legitimet measure of energy dissipitation? intresting thing is joules was a legitimet measure of capacitence discharge energy, new capacitors do not carry this rating. so i guess this is just another way for manufacturers to trick the public. borrowing a term that sort of applies to this technology and abusing its meaning. what i am really asking is if i only spend $20 a peice on these things does it even matter if they say they have 400 or 1000 joules? funny thing is 10 year old ones that had only 70 joules still function fine.
i wish that manufacturers of devices that involve potential safety issues were not alllowed use marketing tricks like these.
i realize you get what you pay for. but when safety is involved they should have to meet higher standards.
also, these devices that are under $50 are all listed as "temporary portable power tap" and not as "tvss" i think this is how they get around good construction. then the boxes say right on them "surge protector strip". this false advertising just doesnt seem right to me.

ron g.

 

[Guest]

Re: i cannot understand how most surge strips can be safe. p

I know that the APC Line-R Automatic Voltage Regulator is a consumer level product (can you say bush league?), but I am wondering how they compare in surge protection vs. an APC Surge Protector. I know that good line conditioners start in the $400 range and go from there. Is the Line-R a pretty good surge suppressor? They are in the $80 to $100 range depending on VA (600 vs. 1200). Also, do they "wear out" like the strip style surge suppressors do?
APC Line-R 1200 VA

Also, what are the thoughts about "Wave Tracker" surge suppressors that more closely follow the sine wave (rather than having one glass ceiling for clamping voltage)?

I am trying to soak this up like a sponge. It is very important for my niche.

 

[iwire]

Re: i cannot understand how most surge strips can be safe. p

Originally posted by rong111:
that is how all of these work. they take a surge and dump it to the earth.

That is really not what happens to surges created by the utility, those surges go back to the transformer that the circuit originates from.

That could be through the earth but not to the earth.

 

[ryan_618]

Re: i cannot understand how most surge strips can be safe. p

Originally posted by iwire:
That could be through the earth but not to the earth. [/QB]

But I thought the earth was the great storage facility of electrons!

 

[rong111]

Re: i cannot understand how most surge strips can be safe. p

sorry i used the wrong terminology when i say earth i tend mean ground. i have a habit of saying that. what i meant is that the surge strips themselves (all but the best ones) work by taking excess current\voltage and sending it to the ground(green wire) rail. at least everyone i ever took apart works this way. you have mov's on line and neutral connected to ground. if a overcurrent\voltage occurs the mov's(hopefully) close and conduct the current to the ground. thats what i meant. whether i am correct about this or not i will listen to you guys.

also i was wondering about what dereck said. if i can draw 40 volts through these mov's at rest how come the ones on the line side do not trip the mains? actually i can think of why, but it is kind of complex. i think the key word i used was "rest". it depends on what their current draw potential is i guess? 40 volts at no load (if it stays at that) may not be enough to heat a breaker enough to open. still this doesnt seem like a good thing. i always thought that a ground (in my case emt) should carry as little voltage as possible? as far as i know it is rarely zero volts, though. it is enough to make the radio shack outlet tester show tied or open grounds on these things.

as for cheap line regulaters those are transformers and coils not a ups. they just don't do the job as well as a line interactive ups. that's why they are only 80 bucks. the ups's that are cheap stink as tvss devices. they put your 80 bucks into the dry cell instead of good mov's.
i know darn well how to purchase a good single phase ups for over a grand. i was trying to avoid this in this instance. maybe it is not possible to get a really snazzy ups for say $250?
i also know who makes the best mov based tvss. but for that much money i would forgo a mov unit altogether.
i just find it unfair what is marketed to consumers to give them a false sense of security.
on the other hand if a box stated "our product doesnt do much" no one would buy it

anyways, what is really still on my mind right now is how i can get a decent tvss that will NOT cease to conduct electricty once it's mov's are exhausted. and still not overheat once the mov's konk out. is something like this possible?
because i have one application where the unit must stay on line no matter what. even if that means passing a surge through to the connected equipment.

alright i'll check back here after work.

ron g.

 

[dereckbc]

Re: i cannot understand how most surge strips can be safe. p

Ron G. I am afraid you have some misconceptions about surge events. I say this because of your statement ?they take a surge and dump it to the earth?. That would be extremely rare event on an AC service. According to ANSI/IEEE 95% of all AC surge events occur ahead of the transformer. So the transient event is in the differential mode (L-N) rather than the common mode (L-G). So what I am saying is earth ground has nothing to do with most events on an AC service system. It would take an event after the transformer to produce a surge in the common mode. Most common mode events are with services like your CATV and telephone service.

With that being said, the best approach to protect your home, office, or business is to start at the service entrance, rather than the point of use. The ?point of use devices?. (class A) are to small in size to offer much protection. So if I were you I would look into installing a class C or B device at your service entrance.

In regards to 40 volts on the ground, what points are your measuring? There should be 0 volts. 40 volts indicates a open circuit somewhere. First check the voltage between the neutral and ground pins on you receptacle with no load. It should be 0 volts. If not the problem is with your house wiring. With a load the voltage could be as high as 2 to 4 volts, but not 40.

 

[Guest]

Re: i cannot understand how most surge strips can be safe. p

Originally posted by rong111:
<snip>as for cheap line regulaters those are transformers and coils not a ups. they just don't do the job as well as a line interactive ups. that's why they are only 80 bucks. the ups's that are cheap stink as tvss devices. they put your 80 bucks into the dry cell instead of good mov's.
i know darn well how to purchase a good single phase ups for over a grand. i was trying to avoid this in this instance. maybe it is not possible to get a really snazzy ups for say $250?
<snip>anyways, what is really still on my mind right now is how i can get a decent tvss that will NOT cease to conduct electricty once it's mov's are exhausted. and still not overheat once the mov's konk out. is something like this possible?<snip>ron g.

I am wondering if you were addressing my question about Line-R's in your reply quoted above?

I know that Line-R's are not UPS's. I know that good TVSS's are 4-figures. I know that good line conditioners start at $400.

You are seeking a good surge suppressor under $250. I am wondering how effective the Line-R is for TVSS. TVSS is one of its published features.

A $80-$100 Line-R is less functional than a $400 conditioner; not a UPS; it's not a 4-figure TVSS-- but as a budget alternative how does a Line-R stack up as a TVSS? A Line-R is a lot more massive than a strip TVSS so there is room in there to do more than a strip. Question: How effective is a Line-R at TVSS compared to a TVSS strip?

 

[rong111]

Re: i cannot understand how most surge strips can be safe. p

it honestly looks to me like these devices (cheap tvss's)have mov(s) on l and n that are bridged to g. via direct component connection (mov's). i was just thinking that they take a surge that occurs on l or n and close, thus completing the circuit with the ground.

i understand where most ac surges occur. i was speaking of how the cheap tvss functions as a component. not how the poco works. i just wanted to make sure we were talking about the same thing. if i am still wrong please inform me.

as for the 40 volts, i meant at no load between l and n ONLY when one of these devices is on the branch! mind you not all of them have this problem. i know my wiring is ok(actually it is horrible but the ground is good at least). any outlet in my home does not see more than 4 volts on the conduit(ground here)under hard load. also why does the radio shack outlet tester (that i know works) find floating ground or l+n tied on some of these things?

dereck, i know you are completely right in the theory you have stated. that does not mean all of these devices have been designed properly however.
what upsets me is that they got past ul while probably being unsafe.

awwt, the $80 line regulators i think are mostly snake oil. once again i think the key to all of this is you get what you pay for. i would still hope that if ul lists them they are at least safe.
i actually saw "on line" ups's for under $100! these obviously do not work as they state they do?

one thing that i am wondering about right now though. i understand the manufacturers claims as to why they will not guarentee products that are "daisy chained" to a tvss. i.e. a stereo receiver that has two "accessory" outlets in the back with a cd player and tape deck plugged in those outlets and the receiver then plugged into the tvss. regardless of their claims, in this instance are the "cd player" and the "tape deck" also well protected?

honestly i don't think surges are such a huge problem. at least not around here. i mean catastrophic surges. the loading and unloading of circuits of homes on the same xformer and moreso devices in ones own home are really what kills appliances i think. i have 70 joule strips on devices that have gone unhurt for 15 years. also i think really sensitive equipment like todays very fast cpu's are more affected by under voltage than slight over voltage. a computer is probably better off to have the power completely cut very quickly than to see a prolonged brownout.
on the other hand killing the power to a windows machine can very often corrupt the hard drive which is why ups's are great.

i just have one more question. every one of these devices states "not for use around aquariums" for obvious reasons. what would one use in a residential situation where the power tap may become wet but not submerged? can i fix this just by using a gfci? my aquariums allready have gfci's on them. but of course i know better than to stick in my hand when energized even with the gfci.

thank you,
ron g.

 

[rong111]

Re: i cannot understand how most surge strips can be safe. p

actually i just read all about this somewhere!
dereck you were right on. i didn't doubt you anyways. the ground presence is only for common mode surges(lightning). i misunderstood the circuit topolgy. also you were right in the respect that point of use units do not have a great ground. that is one big reason service entrance units are so much better. a lot less wire to get to the ground.
so why do all these manufacturers make such a big deal about the ground?

also, in the same article i read that cheap ups's provide such noisy power and such a square wave that you are better off without one than with one! it states that computers are rarely destroyed by power loss(i was wrong again!). it is data that is what one wants to protect with a ups. so a cheap ups is what will really wreck a computer. it goes on that even "pure sine wave units" if under $2,000 are no where near a sine wave on a scope. more of a stair step.

i feal dumb for not knowing all this stuff.
just read past all my other posts in this thread to this one please

ron g.

 

[dereckbc]

Re: i cannot understand how most surge strips can be safe. p

Originally posted by rong111:
as for the 40 volts, i meant at no load between l and n ONLY when one of these devices is on the branch! mind you not all of them have this problem. i know my wiring is ok(actually it is horrible but the ground is good at least). any outlet in my home does not see more than 4 volts on the conduit(ground here)under hard load. also why does the radio shack outlet tester (that i know works) find floating ground or l+n tied on some of these things?

Glad you figured out some of the problems. But lets get back to the 40 volts between where and where? Also you shouldn't read any voltage on any EGC or between any EGC and coduit.

What is 1 + n. Are you talking about Line and Neutral. 1 + n means redundacy in a rectifier battery plant or UPS to me. L, N, G, and IG are the popular terms used.

Now that you know a little about "point of use" TVSS devices, go here http://www.tripplite.com/products/suppressors/isobar.cfm#2 and look around, you should find some quality devices in the $50 to $75 range. Stick to the Isobar line under Tripplite. Ther are others, but these are affordable.

What you discovered about UPS is the small inexpensive ones are "approximation of sine wave" stand-by units. They do not offer any line conditioning, and as you say they generate a square wave or step wave at the 12-volt level then use a transformer to step up the voltage and clean it up to some degree. But I agree there junk. Some data equipment will work with them while others won't.

But you do not have to go up to $2000 to get a decent line interactive UPS. MGE, Invensys, and APC make them for less than a $1000 for home use.

Good Luck

Dereck