computer Surge Suppressor-protector question

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On 3/13/2011 9:24 AM, Tony Miklos wrote:

What's he amp rating on your service? Is it 3 phase commercial? Do you have a BFS Big Freaking Switch on the main power coming in? :-)
TDD
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On 3/13/2011 2:18 PM, The Daring Dufas wrote:

200 amp, single phase, one to the house and one to the garage, think of a farm type set up. Sorry I don't have a big freaking knife switch like in Frankenstein but that would be cool! Open air switch with no safety nutn'. Don't lean there.
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On 3/13/2011 1:50 PM, Tony Miklos wrote:

On most of the CT metered service entrances I've installed, there is a big fused safety switch to kill the main power going into the building. This is so the fire department can knock the lock off and kill the power. At a home, the fireman will knock the power meter out of the can to kill the power. In your case, I suppose the power company didn't want multiple meters. :-)
TDD
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On 3/13/2011 3:43 PM, The Daring Dufas wrote:

I didn't want separate meters because the 2nd one would be billed at commercial rates along with a service charge each month. Some time ago I posted here that I have no disconnect to the garage and I got replies saying code doesn't call for a disconnect. Going to the house is the old meter base with jumpers, so I'd say that could be considered a disconnect.
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On 3/13/2011 7:26 PM, Tony Miklos wrote:

Well, I'm considered crazy for working stuff hot but I work everything like it's hot anyway. I'd swap out the meter box for a safety switch.
TDD
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On 3/13/2011 8:45 PM, The Daring Dufas wrote:

Crazy? I agree! I'll put my fingers and tools inside a breaker box with a 200 amp breaker, but I'm not getting near the side that is before the breaker.
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On 3/14/2011 3:54 PM, Tony Miklos wrote:

There have been occasions when I had to kook up a service entrance to a drop and I use a special insulation piercing connector that takes a wrench to install. I would cut the drop loose, swap the meter can for a fused safety switch or big breaker in the range that matches the amp rating of the wire then reconnect the drop with the Blackburn taps.
http://www.elastimold.net/ps/fulltilt/index.cgi?part=IPC3535
I've worked 15kv underground service cable taps and splices to hook up transformers. Little old 240 volt service doesn't scare me but I treat power cables like like they are energized at all times. It's good practice to always treat electrical power with respect. ^_^
TDD
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On 3/14/2011 10:11 PM, The Daring Dufas wrote:

At my old house I saw them working on the underground cables at a big box thing with a lid down by the road. The cables were lying in water! I think it was high voltage because the cable ran 250 feet to my propety line to an above ground transformer and then to my house. (Had it marked for digging purposes.) They were moving the cables around with a long fiberglass? pole. Turned out they couldn't find the short and backtracked and replaced the insulator on the pole a few hundred feet up the road were the fuse blew. It always seemed odd that there were above ground lines except for me and 4 other houses. There was a high tension line above the area and I wondered if that had something to do with our services being underground?
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On 3/15/2011 9:23 AM, Tony Miklos wrote:

Think induction, high voltage burial cable has a coaxial shield.
TDD
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On Tue, 15 Mar 2011 10:23:22 -0400, Tony Miklos

All underground wiring is considered a wet location because they always accumulate water eventually. Underground vaults tend to be swimming pools unless you live in the desert.
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On 3/12/2011 8:43 PM, The Daring Dufas wrote:

I would agree the cascaded protection would be your best bet by far.
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On 3/13/2011 9:16 AM, Tony Miklos wrote:

AH! At last, someone who groks. :-)
TDD
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On 3/13/2011 2:28 PM, The Daring Dufas wrote:

Grok, grok, grok.
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The Daring Dufas wrote:

MOVs are voltage limiters. They are like parallel reverse connected zenier diodes.

MOVs have an energy (joule) rating. They can absorb as much energy as the joule rating (and at that point are still functional). This is a rating for a single surge. MOVs (and both service panel and plug-in suppressors) with very high joule ratings are readily available. If the energy hits a MOV takes are a small fraction of the single hit rating, the cumulative energy the MOV can absorb will be far larger than the stated rating. From another post, the energy dissipated in a plug-in suppressor is surprisingly small. If a plug-in suppressor has a very high rating it is likely to never fail. That is one reason why some of them have protected equipment warranties.
As detailed in another post(and at length in the IEEE surge guide below), some plug-in suppressors will disconnect the protected load if the MOVs fail and are disconnected. Another reason why some suppressors have protected equipment warranties.

The best information on surges and surge protection I have seen is at: <http://www.mikeholt.com/files/PDF/LightningGuide_FINALpublishedversion_May051.pdf - "How to protect your house and its contents from lightning: IEEE guide for surge protection of equipment connected to AC power and communication circuits" published by the IEEE in 2005
The IEEE surge guide says "the vast majority (>90%) of both hard-wired and plug-in protectors use MOVs to perform the voltage-limiting function. In most AC protectors, they are the only significant voltage limiters."
I agree with trader.
If a device is not using a MOV it is probably marked as a feature.

Surges produced in the house are not likely to damage to equipment, which typically has an immunity level of 600-800V.
Service panel suppressors are good protection., The main hole left by a service panel suppressor is that it does not limit the voltage between power and phone and cable wires, which is likely to cause most damage. If phone and cable (and dish) entry protectors are connected to the power earthing system (as in gfretwell's post) and the wires are short, much of that hole is filled. It is still possible to get about 4kV between the coax shield and the center conductor, and a very near lightning strike can induce damaging voltages with the wiring inside the house acting as a loop or long-wire antenna.
UPSs seldom have ratings as high as are readily available in plug-in suppressors. And UPSs with a surge rating often are not listed under UL1449.

The best protection is a service panel suppressor, short wires from cable/phone/dish entry protectors to the power earthing system, and plug-in suppressors for expensive equipment (particularly if it has phone/cable connections).
And as stated elsewhere, if using a plug-in suppressor all interconnected equipment needs to be connected to the same suppressor and external wires (power/phone/cable/...) needs to go through the suppressor.

Meter base suppressors (supplied by the utility) provide protection. The IEEE surge guide talks about the length of wire used to connect a service panel suppressor - as the wires get longer the let-through voltage goes way up. In a meter base suppressor the earthing system is usually connected to the service panel neutral. That means the neutral wire from the meter to the service panel will raise the let-through voltage of the suppressor.
--
bud--

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wrote:

The meter base suppressor works best if the ground electrode conductor lands in the meter base. You really want your grounding paths to be as short and straight as possible. You also want your cable and phone suppressors grounded right there.
The plug in, point of use protection is just supposed to be supplemental to that. A good plug in protector will also have smaller capacitors and maybe an inductive element, meant to shunt off high frequency transients (noise). I live in a place with a thunderstorm just about every day for 6-7 months of the year and I never unplug anything ... but I have several layers of protection for everything.
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On 3/13/2011 12:25 PM, snipped-for-privacy@aol.com wrote:

We had a bad storm system come through The Southeast last week and I was sitting at my computer when I heard my UPS click and my electric heater reset/shut off (electronic control) then a few seconds later a very loud BOOM almost knocked my out of my chair. Computers and network equipment never skipped a beat but my heart did. :-)
TDD
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snipped-for-privacy@aol.com wrote:

I agree. I would not want a meter base suppressor that did not have the earthing electrode system connected at the meter. I don't think I have ever seen one though.

I don't think this is as widely appreciated as it should be. You want the minimum distance to the common connection point.
In some cases, the phone or cable entry point is too far distant from the power service to make a short enough connection.

A surge suppressor at the service is a good idea.
But I don't see why a plug-in suppressor wouldn't be effective if there is no service suppressor. As noted in another post, with no service suppressor the energy that makes it to a plug-in suppressor is surprisingly small because of arc-over at the service and impedance of branch circuit wires. The paper that this comes from is probably still on-line if you want to read it. I would want high joule ratings on the suppressors. And particularly I would want high ratings if the branch circuit to the service under 30 feet. Plug-in suppressors with high ratings are readily available.

Seems to be a real common feature. I never figured out if it does something that is actually useful.

I agree that layers of protection are the best, and where you are you want the best.
You can protect against about anything (including a direct building strike - with lightning rods). (But I don't think I would want to run a ham station with a high antenna in a thunderstorm.)
I liked your pseudolightning rod from another thread.
--
bud--

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wrote:

Landing the GEC in the meter base is pretty common here in Florida. The thinking is to stop a lightning hit before it gets into the house. Typically it will travel down the outside of the mast, over the meter can and down the GEC raceway. Lightning is seen to actually travel on the outside skin of the conductors. That is why they use finely stranded conductors on lightning rods. In the case of your GEC the metal raceway probably carries more current than the 4 ga solid copper wire,

The big problem is time, on the nano second scale. The faster you sink the shot, the less chance you have that some leaks through to your equipment. We had some luck simply using ferrite beads to slow down the shot and a shorter grounding path going the other way. Our operation was protecting about 1000 customers who were not going to turn off their computers every afternoon and unplug them. We were on the leading edge of a lot of lightning protection schemes but we did get pretty good at it. The sooner you can bond all of your utilities the better off you are. I understand nobody is going to be installing a new phone line and most cable TV is already in place but I would not tolerate any new installation that did not come in right next to my electrical entrance ... even if they had to run the cables all the way around the house before it came in. In fact the NEC has added a requirement for a multi system bonding point right at the service, just for this reason.
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snipped-for-privacy@aol.com wrote:

I'm gonna start making 1/0 Litz wire.

I don't know of anything you get at a service panel or plug-in suppressor that has a rise time that is too fast for MOVs on power lines. If there is a very fast rise time the inductance of the wiring will lower the rise time (and spread out the pulse). Gas discharge tubes, which may be used on signal lines, may be slow

I don't remember the basic requirement has changed, but the making the connection is getting easier. You had a link to an "intersystem bonding terminator" recently which I didn't look at right away. Looks slick.
--
bud--

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wrote:

I don't disagree with you, but for 50 to 75, you get an MOV kind that you calleed almost worthless. The ones I've seen do have a LED that stops being lit when the protector has been zapped.
Actually, I got one of those for about 26 or 36 dollars and the next one up was an Intermatic for 130 or 160. The picture and the description said it had 3 LED's iirc, green ones for each leg and a red one that glowed when one of the legs had been zapped. Sounded great, but a comment said that when the guy received it, it only had one LED, and a few days later, I saw ads for that one. I tried to buy it in person at an electrical supply house, but they didn't have it so I just bought the cheap one. I don't know that I ever have such surges and if I ever do, I'll decide what to replace it with if it blows.

And you can keep your other hand off the bus bar.

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