Filter type surge protection in series

[JHZR2]

Given what I assume to be some inline capacitance to "filter" inside of surge protection power strips, and given the circuitry inside of these things, is there any problem with either induced failure, reduced protection, etc. from putting multiple in series?

Im not trying to "double up" protection or anything like that. Just dont want to create any funny issues or problems.

Thanks!

 

[dparm]

I researched this extensively earlier this year, and the conclusion I came to was that surge strips (or whatever you want to call them) are merely "supplemental" to proper whole-house earthing.

A direct lightning hit is going to apply around 25-50,000A. Even a cheap Eaton earthing system can properly divert that to the ground if your building meets 1990 codes.

In the end a surge protector merely diverts spikes to the grounding wire, that's it. Whether you use an MOV-based one (shunt) or series-mode, they all do the same basic job. It shouldn't matter if you connect two together.

 

[djb]

Surge protection strips usually combine a MOV and a fast acting circuit breaker or fuse. The idea is that voltage surge will trigger the MOVs to conduct, and the resulting current spike will cause the fuse protection to open.

Surge outlets typically only have a MOV, perhaps three. This provides some protection against a brief, low-energy voltage spike but probably won't absorb enough power to protect the equipment while opening the slow-acting panel circuit breaker.

Line noise filters put an inductor in series with the power line, likely a common mode choke. This helps slow the rise time of a voltage spike, allowing the MOVs and fuses a little more time to protect the downstream circuit.

Line filters do add a little reactance to the circuit, but it's barely an impact at 60Hz.

 

[Quest]

most brand name filters with surge protection (MOV mostly) comes with sufficient protection (for they have to be at least UL certified) without the risk of fire of severe breakdown (shorts, etc.)

3 things of note:

Any AC line rated capacitors must be "X" or "Y" rated, spec'ed to 280VAC operational voltage, with the following characteristics:

X-capacitors: typically used across the line; Y-capacitors used from line to chassis, typically with higher values to that of "X" capacitors.

They both possess self-healing properties w/o developing shorts, which would risk electrocution or fire (fundamental properties of AC line rated capacitors).

Capacitors (X, Y) are primarily used for HF filtering in this case.

@djb: AC line filters will not slow down the rise time of a spike. It's main/sole purpose is to filter noise above 10MHz and higher.

Lastly: every successive "spike" that a MOV intercepts will degrade it's service life a bit, and until either (a) a seriously large spike comes along and burn it out or (b) the degradation of MOV over years of successfully handling smaller spikes has reached it's end of service life, then a good MOV (high quality ones, such as those made by Siemens or Matsushita/Pana) will burn "open", while cheeper ones mostly made in China or some Taiwan stuff with develop a short.

So long as (a) you don't live in an area prone to frequent voltage spikes, such as living near the vincinity of an industralised section; or (b) you don't live near to a thunderstorm area, typically MOV built into average home appliances including power bar, should last an easy 3yrs+ before they die off (mostly due to MOV shorts).

For those who live close to the industralised section or prone to thunderstorms, I'd strongly recommend the installation of a breaker panel type surge protector to protect the entire house:

e.g. Cutler Hammer makes a full series of breaker panel based surge protector (search ePrey):

http://www.ebay.com/itm/CUTLER-HAMMER-EA...=item3ccc042be5

@ JHZR2: my strong advice is not to touch or modify anything you don't know, including surge protectors typically comes within a power bar or built-in to home appliances. The risk is high and you can easily electrocute or burn down the house.

Q.

 

[JHZR2]

Originally Posted By: Quest

@ JHZR2: my strong advice is not to touch or modify anything you don't know, including surge protectors typically comes within a power bar or built-in to home appliances. The risk is high and you can easily electrocute or burn down the house.

Q.


All Im considering doing is putting two surge protectors, likely an APC one and then a Tripp lite isobar in series with each other, just due to the number of open plugs I need for some stuff I need to power...

Id rather not have to plug each in in parallel for other reasons.

 

[dparm]

You're totally fine to do that. You can get some surge protectors with 14 outlets. Ever consider that? TrippLite, CyberPower, and APC sell some rackmount ones that would be totally fine for this purpose.

 

[dparm]

And yes, the post up top about MOVs having a "service life" is absolutely correct. Quick micro-spikes slowly eat away at their effectiveness. No real way to measure this so just get in the habit of replacing surge strips every few years if you are indeed paranoid.

Or as I mentioned up top, put in good whole-house earthing for <$100 and you'll be safe.

 

[westom]

Originally Posted By: JHZR2
All Im considering doing is putting two surge protectors, likely an APC one and then a Tripp lite isobar in series with each other, just due to the number of open plugs I need for some stuff I need to power...

Obvious are basic safety considerations. Daisy chaining power strips (protector or non-protector) is a human safety threat. A potential house fire. For example, a dog kennel near me caught fire and killed over 20 dogs because power strips were daisy chained.

Second, use a meter. Measure the 'filter' between each plug prong and the corresponding receptacle hole. Except for a possible switch and already required fuse, nothing but wire exists between each prong and socket. Plug both power strips into separate duplex wall receptacles. The electrical circuit (and resulting protection) remains unchanged. But that would be obvious if 'how a protector works' was understood.

Third, you have 'assumed' a protector works by blocking filtering or absorbing a surge. Instead, learn what that power strip reaslly does. Start with spec numbers that every layman can and must read. Post those manufacturer spec numbers to learn even more. If a protector works as you have 'assumed', then how do hundreds of joules inside a power strip filter, absorb, or block hundreds of thousands of joules? Why do those numbers make no sense? Because you are 'assuming' rather than first learning what a power strip does.

Each question is not rhetorical. Each questions needs an answer so appreciate problems with your power strips.

Fourth, MOVs do degrade. And then we use numbers so understand the problem. One MOV manufacturer describes how to test MOVs. MOVs that fail normally and without threatening human life must only degrade. That means an MOV's voltage (Vb) changes. And so the MOV test:
Quote:
The change of Vb shall be measured after the impulse listed below is applied 10,000 times continuously with the interval of ten seconds at room temperature.

Destructive surges occur maybe once every seven years. Why do some protectors fail after only one or a few surges? Grossly undersized. A $4 power strip with ten cent protector parts selling for $35 or $100. A profit center (not protection) are those power strips. Don't listen to hearsay or subjective claims. View the numbers. How does that power strip stop or absorb hundreds of thousands of joules? Where is the protection?

It sells because so many do not even know the above four simple concepts. Because so many 'assume' rather than learn numbers even provided with every protector. If a protector 'sacrifices itself', the protector was grossly undersized. Ineffective. And a potential fire problem. More numbers and technical facts can be provided to demostrate the threat.

Those power strips need protection only possible from what also protects every household appliance. What protects every dimmer switch, GFCI, and the dishwasher is also necessary to protect undersized power strips.

Where to begin? Post manufacture spec numbers for the APC and Tripplite protector. So that we can discuss what those products really do. And then use that knowledge to identify more effective and less expensive solutions. Typically ten or 100 times less money for a superior solution.

 

[Quattro Pete]

Originally Posted By: westom
Daisy chaining power strips (protector or non-protector) is a human safety threat. A potential house fire.

What causes that? How is it different from daisy chaining extension cords? Sorry, I know nothing about it, hence the curiosity.

 

[westom]

Originally Posted By: Quattro Pete
What causes that? How is it different from daisy chaining extension cords?

First, an extension cord is only a temporary connection. Never operate a refrigerator from an extension cord. Since that would be a permanent and dangerous connection. A power strip is designed to be a stand alone, fixed, power source. Extension cord and power strip are electrically different.

Second, OP is discussing fixed power by daisy chaining power strips. Power strips cannot be daisy chained for a long list of little reasons. Including the same reason why extension cords are not designed to be daisy chained.

More problems. A 100 watt incandescent bulb is often considered less than 1 amp. So why does a 100 watt bulb draw maybe 8 amps on power up? Put three 100 watt bulbs in a power strip. 24 amps. Why does that not trip a 15 amp circuit breaker? Just another electrical characteristic; another of so many reasons why power strips are not to be daisy chained.

Many will see the 15 amp breaker on that power strip. Then assume three 100 watt bulbs would trip that breaker if drawning 24 amps. It does not work that way. We know from generations of experience, the resulting fires, and many tiny electrical reasons that power strips must not be daisy chained.

Extension cords are not designed to be daisy chained and are not designed for fixed power sources. Wall receptacle must exist within six feet of anything that might require power. Code calls for a receptacle, at most, every 12 feet to avoid extension cords and a potential house fire.

 

[dparm]

Westom, would you say that large residential high-rises are generally more robust than a single-family dwelling when it comes to their earthing/grounding? I would suspect that a 15 or 20 story building must be subject to strict code to the likelihood of direct lightning hits.

 

[JHZR2]

I appreciate the comments, but without the actual solution associated with the commentary, It's not really complete. I get that an extension cord is by definition temporary. But in the end all, it's all about ampacity. If the load is below the ampacity rating of the conductor, the question of load is not a major consideration, an mobody's home is going to burn down.

This is all about plugging in a tv, DVD, stereo, computer and a few other things with total load far below the dedicated circuit rating.

It's entirely about capacitance and other active components, in series or parallel on an outlet, and it's effect.

 

[westom]

Originally Posted By: JHZR2
It's entirely about capacitance and other active components, in series or parallel on an outlet, and it's effect.
Series capacitance and other active components are virtually non-existant and irrelevant to 60 Hz electricity. To the TV, stereo, etc, that power strip connection is direct - just like an extension cord.

You are assuming something that the box does not contain and does not claim. That power strip connects your TV, stereo, etc directly to AC mains - a wire connection. Except for one very important device - a 15 amp circuit breaker.

Safety codes say daisy chaining power strips is a fire threat. Wall has a duplex receptacle. One strip connects to each outlet.

Three 100 watt incandescent bulbs are rated at 2.5 amps. So why can three bulbs also consume up to 24 amps? And not trip that 15 amp breaker? Numbers in that post cannot be ignored to underatnd why. Otherwise just read an executive summary. That says daisying chaining power striips is a safety threat. Chance of fire iw quite low. Some juridisditions get fussy about violating that rule.

 

[westom]

Originally Posted By: dparm
Westom, would you say that large residential high-rises are generally more robust than a single-family dwelling when it comes to their earthing/grounding?

A concrete and steel building is one big earth ground. Concrete (when encasing steel) beccomes an especially good conductor. Of course, better is to not have lightning current flowing inside any part of a building. So a lightning rod is earthed to make an even better path to earth outside the building.