Whole house surge protectors

[Ignoramus32515]

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).

3. 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

 

[Tim Shoppa]

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

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).

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).

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.

Any thoughts?

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.

 

[Ignoramus32515]

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.

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

 

[Jim Thompson]

On Wed, 21 Dec 2005 17:59:07 GMT, Ignoramus32515

[snip]

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

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

 

[GregS]

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).

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

 

[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).

3. 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?

http://www.state-elec.com/Leviton/50240_meter.pdf

 

[David Harmon]

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

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.)

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

 

[Pig Bladder]

On Wed, 21 Dec 2005 17:59:07 GMT, Ignoramus32515

[snip]

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

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

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

 

[Jim Thompson]

On Wed, 21 Dec 2005 17:59:07 GMT, Ignoramus32515

[snip]

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

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

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

Apparently before history.

...Jim Thompson

 

[ehsjr]

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?

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.)

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).

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

3. 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.

It does. 880 joules, according to the spec:
http://www.apcc.com/resource/includ...e_sku=SU2200NET&CFID=1734620&CFTOKEN=46267403

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

 

[Tim Shoppa]

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


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

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.

 

[qrk]

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).

3. 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've seen this company's product in use in FAA installations.
http://www.lightningprotectioncor.com/

 

[Jim Thompson]

I've seen this company's product in use in FAA installations.
http://www.lightningprotectioncor.com/

Goleta, eh ?

Are they any good?

...Jim Thompson

 

[Riscy]

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 on that?

 

[qrk]

Goleta, eh ?

Are they any good?

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.

 

[ehsjr]

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 on that?

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