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Old 05-20-2012, 02:59 PM   #16
onebuck
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Hi,

UL does not act as an authority in any way. They certify thus allowance of the UL approved label when the tested product meets the standards after testing. You are mixing things here.

IEEE, NEMA, NECA/NEC, SES, ASME and other member organizations have standards guidelines and specifications that are widely used throughout industries for design guidance criteria. These bodies do have governing councils that are continuously revising the code & specifications as technology changes.

We need to stop drifting from the OP.
 
Old 05-20-2012, 03:52 PM   #17
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Hi there,

Quote:
Originally Posted by onebuck View Post
UL does not act as an authority in any way.
yes they do. They behave like they were the Lord Himself.

In my former job, I've often had to deal with UL to get tests done on our products, and eventually get a UL certification for our products. And hardly any testing and/or certification body behaves as bureaucratic and arrogant as UL. Such an attitude is rarely found with non-governmental institutions.
I know UL is a private organization, in theory. But they don't appear as such to their applicants.

Quote:
Originally Posted by onebuck View Post
You are mixing things here.
I'm not. I'm just describing from my own experience how UL appears to the outside world.

Quote:
Originally Posted by onebuck View Post
We need to stop drifting from the OP.
Agreed, but thread drift is what makes a forum worth visiting. It's dreadful when all posts remain strictly on topic.

[X] Doc CPU
 
Old 05-20-2012, 05:17 PM   #18
onebuck
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Hi,

The topic we have been discussing can be beneficial for the OP and others if they wish to dig for themselves.

From an engineering standpoint, I have not had issues with UL. UL does have standards that must be met for the testing criteria.

Local labs were never a problem. Sorry to hear your experiences were bad with UL.
 
Old 05-20-2012, 05:21 PM   #19
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If a laptop manufacturer changes on part inside their machine, then it may have to be resubmitted to for UL testing. Therefore laptops locate a power supply on the power cord. Only that supply and cord need UL testing. Then the manufacturer can make numerous changes to the laptop without harming their UL Listing.

UL is a safety code for human safety. It does not say the unit even does what the manufacturer claims. It only says a unit should not harm humans (ie create a house fire).

Last edited by westom; 05-20-2012 at 05:23 PM.
 
Old 05-21-2012, 11:35 AM   #20
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"have you heard of surge protectors that catch fire?"
True. Some famous places have burned down. Post Office fires, the Governors Mansion in Texas (1980's TV) to name a few.
Cheap junk generally, only tested in the field as with most consumer devices.

"ive read its best to have just one in an outlet so that one duplex outlet is empty"
NO, you use these based on it's posted limits. Choose your loads to be within the limits. If you can only support one device then you have the wrong protector or wrong wiring design.

"or is it ok to have a phone charging on the bottom one and the power strip on top outlet"
For the part a load is a load. Chargers and many modern devices are not true passive loads and create harmonics to be returned to the home or companies wiring. It is a big problem if you have many such devices along with maybe large motor VFD's. It has burned out installed wires and transformers. Fluke offers a special meter to test for that.

"i wonder if an extension cord is ok to use in one outlet with 2 or 3 things in that like a radio and not a damn charging device"
By design an OSHA rules, an extension cord is a temporary device used for a limited time when no installed wiring is close. If you need power often then correct the home wiring to have proper wall sockets. Each point is considered a load under common design. If you add in 20 or 30 more points (sockets) to a circuit with some strip/protector then you can easily overload the home's wiring and create a potential fire or death hazard.


Power strips fail too. All that is wrong with a protector is also wrong with a power strip except they tend to use less power. Some protectors use a bit of power 24/7.

Last edited by jefro; 05-21-2012 at 11:38 AM.
 
Old 05-22-2012, 08:07 AM   #21
Craise
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so i can plug two surge protectors in one outlet?or i cant?

can you get a link of a lowes site with a reasonable power strip?so i know what to buy
 
Old 05-22-2012, 08:16 AM   #22
Craise
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ok i read page two

i wouldnt plug an extension cord in a power strip

on a side note what do you know about emf?

i wonder if all these electrical things affect me

i hate dvd players cordless phones and cfl lightbulbs the most
 
Old 05-22-2012, 08:19 AM   #23
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Hi there,

Quote:
Originally Posted by Craise View Post
so i can plug two surge protectors in one outlet?or i cant?
you can, of course. But it's pointless - that's not more effective than one, just like you can't drive twice as fast when you have two cars.

[X] Doc CPU
 
Old 05-22-2012, 08:45 AM   #24
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Hi,

Quote:
Originally Posted by Craise View Post
so i can plug two surge protectors in one outlet?or i cant?

can you get a link of a lowes site with a reasonable power strip?so i know what to buy
You will be limited by the circuit loads for the outlets. You should never exceed those limits.

As to EMF, most simple surge protectors have limited filtering.
 
Old 05-22-2012, 09:10 AM   #25
westom
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Quote:
Originally Posted by Craise View Post
on a side note what do you know about emf?
EMF from what? Different sources have vastly different numbers. EMF as in EMI/EMC/RFI must be solved where it is done easiest and best. In the power supply. FCC standards define that filtering.

Filtering on power protectors is near zero. Its function is to minimize catastrophic MOV failure; to make fire less likely. Too tiny and not intended to stop (lower frequency) noise entering electronics.
 
Old 05-22-2012, 08:53 PM   #26
Skaperen
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Quote:
Originally Posted by Doc CPU View Post
Quote:
Originally Posted by Craise View Post
ive read its best to have just one in an outlet so that one duplex outlet is empty
That's nonsense. You just have to make sure that you don't exceed the maximum current or power rating.
Actually, this not only makes sense, but is good advice. It's NOT about the current rating (which would suggest separate outlets). Instead, it is about the surge protection itself.

Correct surge protection requires that ALL metallically interconnected devices to share a common single surge protection. Plugging a 2nd surge protector power strip into the 1st one does not add any protection for surges arriving from the power outlet. It does add protection for surges arriving from a connection on the 2nd one.

If these computers are connected to metal ethernet that leaves the area, that metal ethernet needs to be connected through the 1st or only surge protector. There are few that support CAT5, so you have to look around. If you don't have this, you are at risk of a surge causing substantial damage (such as arriving from the power outlet and exiting through the ethernet).

Surge protection is about preventing the CURRENT from the surge from going THROUGH the sensitive devices. This is accomplished by EQUALIZING the voltage between ALL the various wires connecting the devices. The MOVs will short circuit above a certain voltage (usually 660 volts, but in many cases less like 330 volts for 120 volt power strips in North America and a few other places). This short circuit carries the heavy current of the surge, equalizing the voltage so the surge does not force current between the wires through other means that can do damage.

In small surges, the MOVs can survive to continue protecting. In large surges they can be damaged and made non-functional and no longer provide protection. Some surge protectors have a test device to check this. In rare cases or very large surges, the MOVs can actually be catastrophically destroyed. In cases where the high voltage is fed from the utility distribution lines (2400 volts to 34500 volts) due to a short circuit inside the utility transformer, major damage can be expected, and a fire quite likely. The surge protector is likely to take the brunt of this because it will have established the short circuit path, so ignition to a fire will likely take place there, and perhaps only there.

Some surge protectors are simply poorly made and can catch fire when a better built unit will protect and live on.

I do recommend metal frame surge protectors. Unfortunately, the only ones I have seen with CAT5 connections are plastic. You only need the CAT5 connections if CAT5 wiring runs to other places. You can avoid that with either wireless or fiber optic.

I have my entire home setup going though a single plug at 120 volts (and one UPS). I'm running 5 computers which is approaching the limit. Beyond that I will need to either increase the current or (preferred) increase the voltage to 240 volts. Finding a surge protector for that will be harder to do. Unpolarized Schuko protectors from Europe should be usable, since they should have MOVs connected between BOTH power wires and the ground wire (as well as each other).

I also use wireless from my router and cable modem located in another part of the room from where the computers are. The router and cable modem are not protected and are at risk, but the loss there would be small. A separate surge protector with cable coax port can protect them, too. But a CAT5 run between them would negate the protection because surge current would get to take an alternate path that way instead of through the MOVs.

There is an old saying that "electricity takes the path of least resistance". For the most part that is not true. Electricity takes ALL paths, in inverse proportion to the total resistance of each path.

Last edited by Skaperen; 05-22-2012 at 08:57 PM.
 
Old 05-22-2012, 09:20 PM   #27
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Quote:
Originally Posted by westom View Post
Facilities that can never have surge damage always use something completely different that also has a similar name. One 'whole house' surge protector protects everything when properly earthed. A typical lightning strike may be 20,000 amps. So a minimal 'whole house' protector starts at 50,000 amps. These are provided by more responsible companies including Siemens, Square D, Leviton, General Electric, Keison, or Intermatic. A Cutler-Hammer is sold in Lowes and Home Depot for less than $50.

No protector does protection. A protector works by connecting hundreds of thousands of joules low impedance (ie 'less than 10 feet') to earth. Hundreds of thousands of joules harmless dissipated outside mean no surge damage and no fire threats. It is even essential to protect power strip protectors and the power supply that feeds your computer.
This "point of entry" protection is not nearly as effective as it should be if certain other wiring mistakes are made. For example EVERY (there must be no exceptions) metal feed coming into the building must be interconnected here. That include cable, phone, antenna, water, and even gas. If the voltage among all these metals is not equalized, the opportunity for the surge (especially a direct lighting hit) to establish destructive current between these metals elsewhere will exist.

This is an especially difficult goal for ham radio operators, as they often have may antennas and a need for a separate antenna area. An outside hamshack is often a better solution, or other isolation arrangements.

A combination of isolated point of use areas protected through a common surge protection device, plus a whole house point of entry protection, where both are correctly designed, and improve the protection and provide the maximum amount needed.

In rare cases, the resultant common mode voltage rise can be so fast that in certain kinds of electrical circuits, damage can happen, anyway. Smoothing filters can help with this. But in many cases they have major impact, too. For example on cable coax, they would block the RF signals, too. There is no such thing as 100% protection. The art is to do as much as you can where you can, the right way, within economic efficacy.

Gas feed can be especially complicated. A plastic feed might be a more economic solution.
 
Old 05-22-2012, 10:07 PM   #28
westom
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Quote:
Originally Posted by Skaperen View Post
This "point of entry" protection is not nearly as effective as it should be if certain other wiring mistakes are made.
Skapern has posted accurately. Another reason why protection is defined by a single point ground. Ground must provide equipotential beneath the building. If voltage beneath the building is single point (uniform), then a surge need not enter a building to find earth destructively. No current inside a building means best (and only proven) surge protection.

In some venues or when a building is being constructed, the entire structure is surrounded by the single point earth ground. Either a buried ground loop or what was pioneered in munitions dumps. Munitions dumps must never have surge damage. So Ufer ground - a best surge protection - was pioneered in munitions dumps. A least expensive protection for every home is an Ufer ground. But a majority, educated by advertising, have never heard of Ufer grounds.

Again the point. A majority educated only by advertising (subjective claims; no numbers) have never learned what does protection - single point earth ground. Then protectors that fail or even cause fire are acceptable and recommended.

Informed homeowners do what has been standard even 100 years ago. Upgrade the earthing. A direct connection from each incoming utility wire to earth. Or a 'whole house protector when that wire connect make the 'less than ten foot' connection.

Did I mention 'low impedance' or 'less than 10 foot'? If repeated, then it must have serious engineering significance not found in advertising and other urban myths. Did I mention the word ‘scam’ applicable to any recommendation made without numbers and that does not discuss single point earth ground?

IEEE is quite blunt about what a properly earthed ‘whole house protector does A standard entitled 'Static and Lightning Protection Grounding' says:
“…providing only 99.5-99.9% protection.”
Proves to naysayers that it does not do 100% protection. To the informed, an adjacent power strip protector is for maybe 0.2% protection. More damning numbers never discussed by anyone educated by advertising.

Gas line typically have insulators that separate interior pipes from outside pipes. Protection means minimal voltage differences. Unfortunately, what is necessary varies with each gas company. Some want a dedicated ground wire from gas pipe to single point earth ground. Others call that a violation.

Last edited by westom; 05-22-2012 at 10:09 PM.
 
Old 05-22-2012, 10:42 PM   #29
Skaperen
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The shorter to ground the better. 10 feet (3 meters) is merely the maximum for reasonable effectiveness. 1 meter is even better. As straight as possible, thick and heavy, but with smaller strand wires. Welded to the electrode, and deep, even fanned out if practical (especially for RF grounding, but that's another whole chapter).

Point of entry will get most of it. There is still some risk of internally caused surges, and non-metal builds are at risk of externally induced surges (lightning strike outside on other side of building having inductive effects). So the ungrounded point of use protection still helps even when the building is protected at point of entry. But do NOT be tempted to otherwise ground those point of use protectors to earth as that will defeat the point of entry protection.

The point of use protectors can help, but the numbers are usually sales inflated. Sometimes I'm tempted to build my own. Unfortunately for me, the house I live in right now was so stupidly built. Phone and gas on one side. Power and cable on the other. Water comes up inside the middle of the crawl space (but that at least helps keep it from freezing). The sewer line is all plastic so I'm not worried there.
 
Old 05-22-2012, 11:44 PM   #30
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am i clear ?i didn't say i wanted to plug two surge protectors together

theres a wall socket- i can choose the bottom outlet or the top one, but can both be used for surge protectors?

i have 6 outlets on most power strips -i seldom like to use more than 4

i need both outlets because theres a radio a vcr tv monitor computer fan ,sometimes external modem etc

i prefer one to be turned off a lot because i hate vcrs on when not in use and some are always on

all this technical stuff you talk about i dont understand

i just want to know whats safer

Last edited by Craise; 05-22-2012 at 11:46 PM.
 
  


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