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Whole house surge protectors

They are typically two beefy MOV's (hot1-to-ground and hot2-to-ground) or three beefy MOV's (above plus hot1-to-hot2) in a sand-filled metal box. Most also have a little LED telling you that you're "protected" (I think this works on a few mA leakage current through the MOV when the MOV has not yet failed open.)

These are typically installed behind 15 or 20A breakers (at least the smaller ones designed for say 200A panels).

You could, but you'd then face the never-ending battle of getting your local electrical inspector to approve something that isn't UL listed. MOV's hit with a big surge really do explode into tiny little pieces, having those pieces flying about inside your panel isn't the most desirable thing. Sometimes they fail shorted, other times they fail open.

Putting the protection at the service panel (where presumably you've got a nice good low-impedance path to ground) is generally a better idea than installing it far away from ground.

Tim.

Reply to
Tim Shoppa
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[snip]

About five years ago, we had a surge from a lightning strike at an electrical substation some four miles away.

It propagated on _underground_ cabling to my house where it took out all the light dimmers in the house, two computers and a couple of TV sets.

I added a WHSP as well as little UPS's on critical items.

So far so good... fingers crossed ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
"Winners never quit, quitters never win", Jack Bradley Budnik ~1956
Reply to
Jim Thompson

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Reply to
Charles Schuler

Just curious. A discussion that I had in another newsgroup mentioned whole house surge protectors. I understand that they do not provide

100% protectiom from all surges, lightnings etc but they could be useful.

  1. Is a WHSP something that is much more than a (hopefully) beefy MOV in a steel box?

  2. Can I, instead of buying a WHSP, just buy properly rated MOVs and install them at the service panel? (from each power leg to ground, I suppose).

  1. We had some disagreement about whether a UPS such as APC 2200 offers protection from surges coming from the power line. I think that the answer is yes.

Any thoughts?

i
Reply to
Ignoramus32515

Thanks. I read some articles suggesting that WHSP are rated for higher voltage and are not effective for protecting electronics, only motor loads (see, for example, howstuffworks.com, I can provide a reference).

I also want some clarification regarding path to ground and such.

If an electrical surge comes through the electrical line, and a surge protector shunts it to ground/neutral (both wired to the same point on the panel), and the device that's being protected is insulated from ground (say, it is in a wooden cabinet), then would it be beneficial for this circuit to also have WHSP?

Also, would a decent UPS such as a APC 2200 (I got four for $60 yesterday) be sufficient? We just bought an expensive electronic consumer appliance and I want to protect it. Hence my question.

i
Reply to
Ignoramus32515

Apparently before history.

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
"Winners never quit, quitters never win", Jack Bradley Budnik ~1956
Reply to
Jim Thompson

So, how long has that volcano under your ass been dormant?

--
Flap!
The Pig Bladder from Uranus, still waiting for that
hot babe to ask what my favorite planet is. ;-j
Reply to
Pig Bladder

My electric company charges for their device on a monthly rate of $5. Imk pretty sure some kind of protection insurance is provided, but at least the intention is to protect your stuff.

greg

Reply to
GregS

On 21 Dec 2005 09:38:07 -0800 in sci.electronics.design, "Tim Shoppa" wrote,

So how does that work? Putting a puny LED in series with your MOV is obviously a bad idea.

Reply to
David Harmon

You noticed I wrote "I think this works on leakage current...". My belief (based largely on a mix of marketing and marketing!) is that the LED's that accompany MOV-based surge protectors are there to tell you that the MOV has not yet failed open. If the MOV fails shorted, then a breaker trips, so the LED can't be there to tell you that the MOV failed shorted.

So my guess was that the LED was lit from leakage current through the MOV. I have not done a close enough inspection to confirm this guess, and in fact I'm not sure how you wire a LED to do this function! Maybe the LED just tells you that power is applied and tells you nothing about the remaining health of the MOV's. Maybe the LED is just marketing mumbo-jumbo and means absolutely nothing.

Tim.

Reply to
Tim Shoppa

No that's pretty much it - big MOV's. My WHSP is a double pole circuit breaker size/shape - it goes in the service entry panel and takes up two positions where breakers could go. (It does not provide the circuit breaker function, just the surge supressor.)

You could, but it is far more practical to buy a premade unit.

It does. 880 joules, according to the spec:

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However, think of what "protection" means. Compare it to a bulletproof vest. The vest stops small caliber bullets, but doesn't kepp one safe from highpowered rifle slugs. Also, it protects your chest, but doesn't cover other areas. With respect to the ups, the PC can be damaged by a surge entering on the phone or cable wires, or by a power line surge to a device not on the ups and thence to the PC. Or there can be a surge on the powerline that overwhelms the protection the ups provides, like the high powered rifle bullet overwhelms the bulletproof vest.

Ed

Reply to
ehsjr

Goleta, eh ?:-)

Are they any good?

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
"Winners never quit, quitters never win", Jack Bradley Budnik ~1956
Reply to
Jim Thompson

I've seen this company's product in use in FAA installations.

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Reply to
qrk

I have designed the surge protection unit, the biggest issue I found that it requires good earthing arrangement, in fact very high quality as it critually direct surge current to ground, otherwise it useless(!).

This is difficult part of the design, if you seen standard AWG12-AWG20 earth cable to earth at more than 1 meter than you know it likley to be badly installed. It need better than AWG8 earth cable to earth stake, length less than 1 meter.

Any comment > Just curious. A discussion that I had in another newsgroup mentioned

Reply to
Riscy

Only good stuff comes from Goleta! They don't call this area "Silcon Beach" for nuthin'. Our building, an old FAA flight services building, has one of these units. Nice gas arresters protecting this building.

--
Mark
Reply to
qrk

On this side of the pond, you'd never pass an electrical inspection with a GEC (grounding electrode conductor) of the AWG12-20 sizes you mention, regardless of whether a surge protector is installed. #8 copper is the smallest you can use, and bigger services require larger GEC's.

The 1 meter figure is damn near impossible to achieve for most services - the power meter is usually mounted over

4 feet above ground level.

In any event, you want a real good grounding electrode system connected with as short, large and straight a GEC as is practical.

Ed

Reply to
ehsjr

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