Intermatic Whole House Surge Protector ?

Hello,

Having a new service box installed in a residence.

Electrician has never used these before, so thought I'd ask here.

Was thinking of purchasing, and having him install, an Intermatic Whole House Surge Suppressor Model 4870 in the new box. Have had several large lightning storms in the past, and one nearby strike fried the control board on our furnace ! The Intermatic unit isn't all that expensive, about $80 or so.

Any of you folks ever used this model ?

Worth doing ? Thoughts on ?

BTW: If they do ever take a big hit, do they (usually) fail open or closed ?

e.g., would the MOV's be shorting the hot to neutral/ground after a big hit, such that the unit would have to be removed prior to re-initiating service ?

Thanks, Bob

Reply to
Robert11
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After a major strike costed our insurance co 10000 + we installed one and a Lightning arrestor, there is better stuff out there but it costs more. An electrician that hasnt used one? Maybe you need one who is up to date on these issues and what you really need.

Reply to
ransley

=46rom what I see on the web, the unit would be fed through a standard

15A dual-pole breaker, so if it shorted, the breaker would trip, and you'd be running normally, with no protection, until you replaced the unit (and maybe the breaker).

The write up on the LPS unit, which another responder has linked to, says it pretty clearly: "These SPD=92s are not repairable. A defective SPD fails short circuit, in which case the line/branch fuses or breakers operate. A prolonged short circuit may open, and in the process cause rupture of the SPD elements. " My guess is the sames goes for the Intermatic.

Chip C Toronto

Reply to
Chip C

Intermatic surge protectors do not use MOVs - they are electronic. The one you are considering handles 1200 joules and 48,000 Amps. Usually this is adequate to handle typical power-line surges (blown transformer, re-connect time, etc.). It they take a hit, they keep on working (unless it's a direct lightning strike!). They indicate when they no longer are working (I think by yelling "help").

Use of this device does not remove the need for more modest surge protectors on individual devices. The Intermatic protects against surges from outside your home, but it's possible a device inside your home could generate a surge affecting stuff on the house side of the Intermatic.

We have one on our office service (not this model, but the same idea). We've never been bothered by a power surges. We've never been bothered by stampeding elephants either, so that's not much of a testimonial.

Reply to
HeyBub

Lightning wants the shortest path to earth. Make sure that the electrician installs at least two ground rods and although the code allows them to be a minimum of six feet apart I suggest at least sixteen feet between rods.

Reply to
John Grabowski

Why would the intermatic not absorb in-house surges?

Reply to
Bob F

If you want comments, provide a link to information for the model. The Intermatic site did not find 4870 in a search.

MOVs normally fail in thermal runaway and low resistance. All surge suppressors (US) should be listed under UL1449. UL1449 requires overheating MOVs be disconnected by a thermal disconnect.

Carefully follow the manufacturer?s instructions. Keeping connecting wires short is very important.

Everything I saw at the Intermatic site indicated that their service panel suppressors were MOV based.

I didn?t see anything at lightningprotectioncor.com on why their suppressors would be superior.

Equipment most likely to be damaged has connection to both power and signal (phone, cable). If a strong surge produces a 1000A current to earth, and the resistance to earth is a very good 10 ohms, the voltage at the service ?ground? will rise to 10,000V above ?absolute ground?. The way to protect equipment is to keep the ground reference for power and phone and cable at the same potential. That requires a *short* ?ground? wire from phone and cable entry protectors to the ?ground? at the power service.

With adequate ratings, using service panel suppressors, and plug-in suppressors on ?sensitive? electronics with power and signal connections, you can protect against almost all lightning (not including a direct strike to the house - very uncommon).

If using a plug-in suppressor, all wiring (power, phone, cable, ...) going to a set of protected equipment must go through the suppressor.

Reply to
bud--

Hi,

Thanks for help and info. Appreciate it.

You are right; the 4870 model doesn't seem to be listed anymore.

Probably replaced by something newer. Will give them a call Monday and ask.

Bob

Reply to
Robert11

That means that you regular old circuit breaker in you main panel will "protect" the MOV from thermal runaway. Trouble is that once the CB trips you lose protection until to notice the open breaker.

One would think that "someone" would make a MOV equiped device with a self-resetting thermal breaker as part of the design. ALL of them seem to have either fuxes or the MOV self-destructs in a way that doesn't set the device on fire or create a short.

Well, it takes te impulse a little more than a nano-second to travel a foot. If the response time of the MOV is measured in micro or even mili seconds, the length of the wiring just doesn't make any difference.

Amen!

Yep!

That's why all utility wires are supposed to come into the house at the same general location so that the grounds can be bonded together. The "cable folks" often don't bother. Ditto for the "dish" folks.

Well, you can get "local" break out boxes that will protect AC plugs and 1 or 2 coax and/or 1 or 2 phone lines. If the grounds are bonded well at the electric service grounds I suspect that your local suppressor may have a shorter than expected life.

AMEN!

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Reply to
John Gilmer

Accurate replies define protection as earth ground. No protector is protection. Protection is where that surge energy gets dissipated - earth ground. Protectors are simply connecting devices to earth.

Therefore the Intermatic will only be as effective as the earth ground - as others have noted. That means a breaker box ground wire should not go up over the foundation and down to earth. Instead, that ground wire should be through the foundation and down to earth. Every wire foot shorter means better surge protection. No sharp bends. No splices. And all grounds (telephone, cable) make a 'less than 10 foot' connection to this earthing electrode.

Most electricians don't have the 'radio frequency electricity' knowledge to appreciate why sharp wire bends to earth means diminished protection. That ground wire must be rerouted separated from other non-earthing wires. Remember, that ground wire is carrying lightning electricity into earth.

Telephone NID box also has a 'whole house' protector. That protector also must be earthed to the same common point. Cable TV needs no protector since it gets earthed only with a wire. But again, connection should be 'less than 10 feet', no sharp bends, etc.

How to make that Intermatic even better? Expand a single point earth ground with more rods or buried bare copper wire. If your utilities do not enter at a common location, then the buried wire interconnects all ground electrodes to create a single point ground and to further enhance earthing. See a utility app note:

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Most electricians don't understand why they must 'exceed' post 1990 National Electrical Code requirements since electricians only understand 60 Hertz electricity - not RF electricity. What makes any protector effective? Its connection to earth.

Same protector that makes lightning surges irrelevant also makes irrelevant the 'inside the house' surge. If household appliances are creating surges, then you are trooping daily to hardware stores for new dimmer switches, clock radios, and bathroom GFCIs. Why are you not replacing these devices daily? Protection inside all electronics makes those 'inside the house' surges completely irrelevant.

Install a 'whole house' protector so that significant protection already inside all appliances is not overwhelmed. IOW we install protectors to earth direct lightning strikes and to remain functional. Yes, MOV protectors are sufficient sized to earth direct lightning and not fail. Then protection inside all appliances is not overwhelmed. How good will that protection be? How good is your earthing connection - both with better electrodes AND with shorter wire connections? A protector is only as effective as its earth ground - where surge energy must be dissipated.

Reply to
w_tom

The UL required "thermal disconnect" must be close proximity to the MOV and responds when the MOV gets hot at end of life (thermal runaway). It is inside the suppressor.

It operates at end of life - the MOV conducts at "normal" voltages.

A well designed suppressor matches internal protection to the MOVs. They disconnect the MOVs when they are at end of life. For overvoltage (much longer duration than surge and will rapidly destroy MOVs) a few plug-in suppressors will disconnect and save MOVs and protected equipment.

The response time of MOVs is negligible. And surge rise times are over a microsecond.

The problem is voltage drop. Surges are short duration events and thus basically high frequency. The inductance of wire dominates over resistance. The IEEE guide on surges and surge protection:

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information on lead length and voltage drop (pdf page 32). At 3,000A surge current, 6 inches of lead adds 70 volts to the clamp voltage.

It seems like a fairly common problem for signal services to be at distant points. Cable installers are notorious for not correctly bonding to power service grounds. Dish is probably worse.

The IEEE guide has an example of a cable service with too long a ?ground? wire causing a high voltage between cable and power wires (starting pdf pabe 40). The guide says that if a short interconnect cannot be made "the only effective way of protecting the equipment is to use a multiport [plug-in] protector." (You could also run the cable to near the power service, install a second ground block, and distribute from there.)

"Local suppressor" is plug-in suppressor? Should have easier life if interconnection at services is short - would have less use of voltage limiting device from signal to plug-in suppressor ground.

Reply to
bud--

What is this claim based on? If they don't use MOV's what exactly do they use? Also, this would seem to imply that MOV's are not considered electronic components, but I believe by any reasonable definition, they are electronic components.

The one

oted text -

Reply to
trader4

The best information on surges and surge protection I have seen is at:

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"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 is the dominant organization of electrical and electronic engineers in the US). And also:
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"NIST recommended practice guide: Surges Happen!: how to protect the appliances in your home" published by the US National Institute of Standards and Technology in 2001

The IEEE guide is aimed at those with some technical background. The NIST guide is aimed at the unwashed masses.

Even with a very good resistance to earth of 10 ohms and a fairly strong earth current of 1,000A the power system ground rises to 10,000V above 'absolute' earth potential. Protection has more to do with keeping ground references together - short 'ground' wires from signal entrance protectors to the 'ground' at the power service. The NIST surge guru, and author of the NIST guide, has written "the impedance of the grounding system to `true earth' is far less important than the integrity of the bonding of the various parts of the grounding system."

The priority is not short connection to the same earthing electrode. The priority is short connection from signal entry protectors to the 'ground' at the power service.

"Needs no protector"? The IEEE guide says "there is no requirement to limit the voltage developed between the core and the sheath. .... The only voltage limit is the breakdown of the F connectors, typically ~2?4 kV." And "there is obviously the possibility of damage to TV tuners and cable modems from the very high voltages that can be developed, especially from nearby lightning." (A plug-in suppressor will limit the voltage from core to shield.)

For plug-in suppressors, the IEEE guide explains (starting pdf page 40) they work primarily by CLAMPING the voltage on all wires (signal and power) to the common ground at the suppressor. Plug-in suppressors do not work primarily by earthing (or stopping or absorbing). The guide explains earthing occurs elsewhere.

According to NIST guide, US insurance information indicates equipment most frequently damaged by lightning is computers with a modem connection TVs, VCRs and similar equipment (presumably with cable TV connections). All can be damaged by high voltages between power and signal wires.

Service panel suppressors are a real good idea.

What does the NIST guide say? "Q - Will a surge protector installed at the service entrance be sufficient for the whole house? A - There are two answers to than question: Yes for one-link appliances [electronic equipment], No for two-link appliances [equipment connected to power AND phone or cable or....]. Since most homes today have some kind of two-link appliances, the prudent answer to the question would be NO - but that does not mean that a surge protector installed at the service entrance is useless."

A service panel suppressor by itself does not guarantee there will not be damaging voltage between power and signal wires.

Reply to
bud--

A phone line is the most dangerous line in your house, unless you have speakers in trees. We worked on a smart house that had $40,000 in equipment damage when lightning hit a tree next to the pool. It travelled the speaker lines into the house, thru the distributed sound system, thru the distributed tv antenna system, thru the phone and security system and the centralized lighting control. Everything was tied together. The grounding system did work, at least there were no fires. Kitchen appliances were about the only thing unaffected.

Everything was put pack in place, except speakers and lights in the trees. Opto isolators with transorbs were added where the systems were directly interconnected.

-- larry/dallas

Reply to
larry

You're right, of course. MOV are classified as "electronic" components. But metallic-oxide-varistors work like reverse fuses: they short their terminals together. And, like fuses, they (usually) only work once with no indication (other than sometimes smoke) that they won't work again.

Sophisticated electronic circuitry can bleed off surges to ground and continue to function indefinitely. It is the existence of this circuitry that's the difference between a $3.00 "surge-suppression" outlet strip and a $50.00 one.

Reply to
HeyBub

The suggestion comes from the Intermatic web site.

I presume because everything on the same side of the device causing the surge - including the Intermatic - is exposed to the surge. It's not the path of least resistance; it's everything.

Reply to
HeyBub

MOVs will continue to work indefinitely if their rated clamping current isn't exceeded, so they will readily clamp on the modest surges seen every day. The mega surges from a really close lightning strike or a tree branch dropping the primaries into the secondaries is what will cause the MOV to self destruct and usually trip the circuit breaker in the process thereby sacrificing itself to save the stuff downstream of it.

Reply to
Pete C.

I would imagine that the suppressor would absorb the surge to keep it from passing on to other circuits at the breaker panel.

Reply to
Bob F

I think I've answered the question myself. Below is an excerpt from Intermatics datasheets from both a residential and also a commercial/ industrial unit that clearly say both do in fact use MOV's and say nothing about any alternate "sophisticated electronic circuitry." I don;t know of any such alternate components that can handle the huge currents that MOV's can which is why they are used in all the surge protectors that I've seen.

If you have any alternate reference, we'd like to see it.

Residential: Features and Applications: The IG1240RC features six modes of protection and is recommended for residential and light commercial applications. It is intended for installation on 120/240 volt AC panels. The IG1240RC incorporates the newest developments in MOV technology and provides individual component thermal protection and monitoring.

Commercial: For installation in Category "C & B" locations ! Service Entrance, Distribution Panels and Sub-panels ! Parallel installation ! 125k Amps Peak Surge Capacity per mode ! All mode suppression for systems with a neutral ! Line-to-Line, Line-to-Neutral, Line-to-Ground, Neutral-to-Ground ! 6 mode suppression for systems with no neutral ! Line-to-Line, Line-to-Ground ! Integral Disconnect Switch with safety interlock ! Easily replaceable master surge module ! 40k Amp MOVs ! 200k AIC Surge Rated Fuses

Reply to
trader4

Ah, okay. Thanks for the info. I thought a quality company like Intermatic would rely on something other than MOVs, such as zener diodes or gas-discharge tubes. Maybe even motor/alternators.

If they, in fact, are relying on piece-of-shit MOVs (probably made in China), well, might as well stand naked in the rain.

Reply to
HeyBub

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