# No MOV surge suppressor/power strip



## tesseract (Aug 9, 2010)

Just purchased a pre/pro and 2 channel power amp. This will be added to a 3 channel amp, subwoofer amp, HDTV, and then components with negligible draw, a turntable, phono preamp, Blu-ray player and a universal player.

My biggest problem is, only one 120V 15A dual outlet is available. I need a strip or box that provides at least 8 outlets, and living in the Midwest, I'd like to protect my gear. Looking for the most cost effective solution.

What are my options? Thank you in advance!


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## Tonto (Jun 30, 2007)

I have one of these that is new, never been out of the box. If interested I will sell it cheap since I am using the S15's now.

http://www.apc.com/shop/us/en/products/APC-AV-Black-1-5kVA-H-Type-Power-Conditioner-120V/P-H15BLK

There are very good units! PM me if interested. I would like to see it go to a good home.


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## tesseract (Aug 9, 2010)

Looks good, Tonto. I am looking for no MOVs, but will keep the APC in mind.


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## AudiocRaver (Jun 6, 2012)

Dennis, I just bought a Furman PST - 8D with non destructive protection and 8 filtered outlets. Come over and take a look at it if you want. I need to get you over this weekend anyway. Also check the specs online.


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## tesseract (Aug 9, 2010)

That seems to be the ticket, Wayne!

I was looking at Furman, but it was late and I was tired, couldn't find what I thought was there... a non-MOV, non-disposable, permanent solution to my power woes.

See you Saturday!


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## DqMcClain (Sep 16, 2015)

Been using Furmans for years. Simple, solid, and cheap. It's a good way to go.


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## tesseract (Aug 9, 2010)

I was looking at this last night, but it is sacrificial. Joule rating is really low. 

http://www.amazon.com/Furman-M-8X2-...s=audio power conditioner&tag=viglink20759-20

This has a lifetime warranty. Not sure how that works with MOVs.

http://www.amazon.com/Tripp-Lite-Pr...=1-11&keywords=tripp lite&tag=viglink20759-20

Think I'll order up that Furman Wayne recommended, it'll save me some rack space, too.


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## tesseract (Aug 9, 2010)

I am concerned about the possibility of limiting my 3 amplifiers' dynamics. Any advantage with this bigger one, or will the smaller power strip do the same job? 

http://www.amazon.com/Furman-Elite-...36038&sr=1-8&keywords=audio+power+conditioner


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## tonyvdb (Sep 5, 2007)

I've got two of those Trip-lite ones, seem to work well.
I've also got a couple of the Eathereal rack mount ones in my Theater. They've been good so far as well.
I'm not really sure how the warenty covers MOV degradation. Maybe the "newer" design has less ware on MOVs than before?


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## AudiocRaver (Jun 6, 2012)

tesseract said:


> I am concerned about the possibility of limiting my 3 amplifiers' dynamics. Any advantage with this bigger one, or will the smaller power strip do the same job?
> 
> http://www.amazon.com/Furman-Elite-...36038&sr=1-8&keywords=audio+power+conditioner


I do not see an advantage in the specs for current availability. It is a nicer package, but has fewer outlets and the same 15A total current capability.

The Elite 15 PF i ($430) and Elite 20 PF i ($760) offer 45A and 55A peak current for short power consumption surges. Wish they had the current consumption meter, I really like that feature.

Not sure how they do it, but even though there are MOV devices in their designs, they say they are non-sacrificial.

I still have to take measurements to confirm, but I think the one I got has solved the noise floor problem I had from the HDMI into my AVR from my music server. HF and RF Noise isolation between powered components is a big part of what their products achieve.


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## Talley (Dec 8, 2010)

AudiocRaver said:


> I do not see an advantage in the specs for current availability. It is a nicer package, but has fewer outlets and the same 15A total current capability.
> 
> The Elite 15 PF i ($430) and Elite 20 PF i ($760) offer 45A and 55A peak current for short power consumption surges. Wish they had the current consumption meter, I really like that feature.
> 
> ...


I'd be willing to bet it's all because of the power supply in the server. those are very bad noise makers.


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## AudiocRaver (Jun 6, 2012)

Talley said:


> I'd be willing to bet it's all because of the power supply in the server. those are very bad noise makers.


Entirely possible. It is a special power supply selected for low fan noise, but does not have special electrical noise specs, and switching supplies are notoriously poor in that category. The filtering in the Furman conditioner may have solved it, still have to take measurements to verify.


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## AudiocRaver (Jun 6, 2012)

The fact that the HDMI comes off of the video card complicates it all further. How quiet is the power on the video card?


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## Talley (Dec 8, 2010)

AudiocRaver said:


> The fact that the HDMI comes off of the video card complicates it all further. How quiet is the power on the video card?


Didn't think of that and no idea. Everything feeds off the rails on the power supply... Hardforum.com is a website I use to be on for a very long time and only seldom visit anymore since I got out of PC building about 5 years ago but they would do torture tests on power supplies and look at power quality stuff like that. I know the more expensive models definately rate decent but just like AV gear they are a dime a dozen and in the end perform the same task.


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## lcaillo (May 2, 2006)

If one is concerned about available current the only thing that you can do about it is have the least amount of in line conductors. Any filtering is either going to be an inductor, which by its nature is current limiting, or capacitive, which is parallel and has no current limiting effect. MOVs are parallel and have no impact on current. I have never understood the aversion to MOVs but that is another matter.

No power strip connected to the amps is best for current, but frankly it is unlikely that there is any limiting until you get to very high current levels and then the circuit from the panel has to be considered.

With respect to power supplies, what you usually get in better supplies is independent rails for different parts of the system, with more stability and filtering between the supplies. Any switching power supply has to be suspect for noise and if you have a noise problem filtering may help but sometimes the noise in lousy power supplies ends up being common mode and hard to relieve.


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## Savjac (Apr 17, 2008)

I have been reading into this situation for some time as I have one of those large power conditioning boxes with a bunch of outlets and a power cord that rivals a large garden hose and is just about as long too.

I found that most manufacturers want their power un-messed around with and in particular, that Emotiva "Recommends" that their equipment should be plugged directly into the power outlet as they have built in protection. It would also appear that other equipment providers feel nothing greater than a surge suppressor should be in line with their stuff. I have been unplugging one thing at a time and I think things are working a tad better. So what Wayne suggests is more than enough and could easily be recommended.


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## tesseract (Aug 9, 2010)

This is how Furman protects the MOVs that protect the gear.

http://www.furmansound.com/swf/furman_smp_plus.html

Wayne and Talley, the "D" designation in the PST-8D vs. the PST-8 includes digital specific filtering.

I ordered the strip that you recommended, Wayne. It is guaranteed to arrive when my new pre/pro and amp do.

I called Furman, the only way to step up is to go to this bad boy that you recommended. Something I will think on when I get a dedicated room, and will look at Panamax (Furman built), too. There have been reports from the field that dynamics are limited by the more expensive processor, so, caveat emptor. 

http://www.amazon.com/Furman-Elite-..._UL160_SR160,160_&refRID=1GNB9793RK15NM27N2EZ


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## Talley (Dec 8, 2010)

I'll admit that surge/mov protection type stuff is not my forte'. I remember a discussion with my uncle months ago and I asked him what his opinion was and I remember his comment:

"I have zero ups, filters or surge protection on my AC lines" 

Do I think thats safe.. well not sure he does have 6 figures tied up in equipment. He claims though the 10kVa isolation transformer that feeds his audio panel protects it. I need to look into that. Transformers pass through frequencies so I doubt that is a fail safe.


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## AudiocRaver (Jun 6, 2012)

lcaillo said:


> If one is concerned about available current the only thing that you can do about it is have the least amount of in line conductors. Any filtering is either going to be an inductor, which by its nature is current limiting, or capacitive, which is parallel and has no current limiting effect. MOVs are parallel and have no impact on current. I have never understood the aversion to MOVs but that is another matter.
> 
> *No power strip connected to the amps is best for current, but frankly it is unlikely that there is any limiting until you get to very high current levels and then the circuit from the panel has to be considered.
> *
> With respect to power supplies, what you usually get in better supplies is independent rails for different parts of the system, with more stability and filtering between the supplies. Any switching power supply has to be suspect for noise and if you have a noise problem filtering may help but sometimes the noise in lousy power supplies ends up being common mode and hard to relieve.


Thanks, Leonard.

I have scratched my head over the current availability question many times, and end up agreeing with your logic. This time I had to pull out the calculator and do a little analysis.

I have used the "water tower" analogy before about power supplies in audio products, and there are some who seem happy with it and others who argue against it. After thinking about it while working out this analysis, I am more convinced than ever that it is a valid analogy and that the source (the pipes bringing water into the water tower and the pumps and wells before that) are likely to have no practical effect on audio performance or dynamics for an amplifier operating within its design range.

The following analysis has been grossly simplified in favor of needing more current from the outlet and power source for an instantaneous load, and shows it to be accomplised very easily.









Here is a circuit view of a 300 W power amp with a 55 V power rail filtered by a 10,000 uF capacitor, which is not very big for a decent power amp. The power diode is assumed to be perfect and lossless, the power transformer works at an impedance ratio of

120 / 60 = 2:1

and is considered lossless. The source is one phase of a 240 V transformer, also lossless for this exercise. The power source is considered resistive for this exercise, which is fairly accurate in the 60 Hz range.

Power distiribution inside the house for a 15A outlet set is typically 12 gauge wire, which has

5.2 ohm / km
5.2 ohm / 3280 feet
5.2 * (100 / 3280) = 0.16 ohm per 100 feet

resistance of 5.2 Ohms per killometer or 0.16 Ohms per 100 feet inside your house, a conservative number, and is fed by a perfect voltage source.

That 0.16 Ohm becomes

0.16 * 2 = 0.32 Ohm

by virtue of the power transformer's impedance transformation effect, which is one way of thinking of a power transformer, and is just the way they work.

What happens at the power bus when the output load draws a big power impulse? 300 W power into a normal load gives

300 W = 49 V / 8 Ohm load
-> 6.1 A rms current draw normally for 300 W power

Our 1 kHz square wave output pulse into an 8 Ohm load causes the following droop on the 55V supply rail:

( I * T ) / C = V
( 6.1 A * 0.5 mS ) / 10,000 uF = 0.3 V droop

Let's say the load instantaneously drops to 2 Ohms and the amplifier is able to supply the load for one cycle of a 1 kHz square wave without blowing up or shutting down. Looking at the positive half of that event (the negative side is handled by the other half of the power amp), for 0.5 mS there is a current draw of 

49 V / 2 Ohm load = 24.5 A

49 V * 24.5 A = 1200 W instantaneous power

How much does the power supply droop in 0.5 mS with that current draw? Looking at the power supply filtering cap:

( I * T ) / C = V
( 24.5 A * 0.5 mS ) / 10,000 uF = 1.2 V droop

Not enough for any concern.

Assuming a triangle 60 Hz power source wave because it is a lot easier to work with than a sine wave, reprlnishment takes place as the wave stays above 43 V. The following table shows calculations for 1 kHz and 100 Hz single-cycle pulse into 8 Ohms and 2 ohms.

Table:

```
Sq Wav Freq		1 kHz	100 Hz
  1 cycle	
Inst Power 8 Ohm	300 W	300 W
Inst Power 2 Ohm	1200 W	1200 W
With 8 Ohm Load:
  Power Rail Droop	0.3 V		3 V
  Concern?			No		No
With 2 Ohm Load:
  Power Rail Droop	1.2 V		12 V
  Concern?			No		Yes
  Power Limited		N.A.		230 W
    8  Ohm
  Recovery Time		N.A.		15 mS
  Avg Recovery		N.A.		6 A
    Current
  Source Vdrop		N.A.		1.8 V
    at secondary
  Concern?			N.A.		No
```
Recovery Time for Power Rail, amount of time the power supply transformer secondary voltage is above the droop level and can replenish it (two times the 12/55 portion of the wavveform, twice per cycle, -> x4)

( 12 V / 55 V ) * ( 1 / 60 ) * 4
= 15 mS

( I * T ) / C = V
( V * C ) / T )) = I
( 12 V * 5 mS ) / 10,000 uF = 6 A

Power Source Limitation, voltage drop from source resistance
6 A * 0.32 Ohms = 1.8 V drop

Additional points:

A power conditioner can (should) be designed to add no significant effective source resistance at 60 Hz, while it can add inductance for HF and RF filtering. A proper design will not be a limitation to power supply replenishment.
Above 1 kHz, NO SIGNIFICANT REPLENISHMENT CURRENT will be drawn from outide the amplifier. The use of local bypass capacitance is a standard analog design practice. This usually includes film and ceramic capacitors with extremely low internal resistance/inductance within inches or even a fraction of an inch of the curcuitry being served. One might find a 0.1 uF and a 1 nF cap on each supply rail for each stage of circuitry.
As Leonard pointed out, many power amp designs include regulated supplies for each circuit stage, helping even more to eliminate problems from unusual signal/loading situations.
Longer (lower frequcney) power dissipation "surges" extreme enough to tax the power supply design would simply be outside the design parameters for an amplifier.
This is an extremely oversimplified and extremely conservative example. It shows the source able to easily replenish the power supply in an amplifier under an extreme instantaneous signal or load condition. House wiring and in-room conditions would have to be extremely degraded before they could become a problem.
Conclusion:
Even with a sub-standard power supply design, in this example I can not see that there is any way for reasonable real-world home power source/wiring to become a limiting factor to this amplifier's performance. A reasonably-well designed amplifier will have all the capability it needs built in to handle dynamics and strange loads.

Of course, listening tests are always in order, and should include repeated A-B comparisons to ensure that biases are not a factor.


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## Talley (Dec 8, 2010)

I'm rushing to clean the house for a party.... I glanced over the info and will need to analyze it later.

one thing that jumps out is a 15ms recovery is a concern and says no?... I think 15ms is a tad long... I'd prefer to stay under 5ms

Edit: most homes with 15a circuits use 14g wire which has a resistance of 8.28 ohms. You also did not factor in voltage drop at the source. I've monitored my circuit to my amp and have seen peaks of just under 1800 watts. This was playing at 0db with 5 channels driven using a Fluke 289 logging meter that was also calibrated (from work). I'd have to see if I can get ahold of that meter again so I can post some graphs.

You gotta factor in some voltage drop at the device from the source during these calculations. This is the reason I ran #4awg from my panel to my outlet box which was 65 feet away. I didn't experience more than a .5v drop at the source. However had it been 14g wiring you could of seen as much 5 volts of drop.... but not sure how "instantaneous" this is either when dealing with AV equipment.

I really need to get that meter again and do some more testing.....


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## AudiocRaver (Jun 6, 2012)

Talley said:


> I'm rushing to clean the house for a party.... I glanced over the info and will need to analyze it later.
> 
> one thing that jumps out is a 15ms recovery is a concern and says no?... I think 15ms is a tad long... I'd prefer to stay under 5ms


Why?

Read my reasoning when you have time.

15 mS is the time window in the example AVAILABLE for recovery, it might happen much faster.

Also, with a typical linear supply, with 4 rectifiers and a center-tap-grounded secondary, both the positive and negative sides of the wave can contribute to recovery. The example simply shows that both polarities can contribute, each for 7.5 mS, if needed. It is also an EXTREME case, a 300W amp recovering from a 1200W pulse. Give us a break.:boxeryou know I jest):bigsmile:


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## AudiocRaver (Jun 6, 2012)

The "no" means that the recovery only causes a tiny drop in source voltage (additional 1.8 v on 55 v supply rail) and THAT is not a concern.


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## Savjac (Apr 17, 2008)

In my strolling through the audio interwebs I came across this, a power strip recommended by Naim audio
The Wiremold L10320 is said to be the best and without all the other stuff built into it. ($99)

Or..you could go with the SuperWiremold Deep-Cryo power strip ($399)


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## Talley (Dec 8, 2010)

AudiocRaver said:


> Why?
> 
> Read my reasoning when you have time.
> 
> ...



I dunno man I had a fluke 289 setup for a night at my house and played FURY all channels driven and my highest peak was 1700 watts but I am driving 5 channels too. This was on a heavy resolution i can't remember but something like 30 samples a second or something like that. I didn't look at the chart and the meter is owned by my work... I need to get ahold of that meter again. you can set it up to logg alot of stuff. Had a 400amp clamp meter with it too.

Honestly I can't really comment on all that math since without doing my own testing I'm blind to decipher. I'd need to bench test some equipment doing some load testing to find out.


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## Savjac (Apr 17, 2008)

Talley said:


> I dunno man I had a fluke 289 setup for a night at my house and played FURY all channels driven and my highest peak was 1700 watts but I am driving 5 channels too.


Am I reading this right that a 125wpc amp driving 5 channels can do 1700 watts ? At the speaker or how would that work ??

Just curious.

Thanks


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## AudiocRaver (Jun 6, 2012)

Tally, Thanks for looking at my numbers, I know I went overboard with that , I was curious to see where it went more than anything. Thank you for the correction on the wire gauge and for some real-world measurements. I also kind of question where all that power went but I suppose your sub may have added to it. I agree that the voltage drop at the source is the big thing we are after here ,that was in my analysis but got buried.

no doubt about it, the power that gets dissipated has to be replenished. I am very curious about how long that 1700 watts lasted. The measurement equipment you are using is certainly capable of measuring fast current peaks. If you are logging at 30 samples per second, that is only once every two cycles for a 60 Hertz source. If I am not mistaken, the question was about AV equipment needing to draw instantaneous peaks of power from the power source and wiring rather than from its own internal supply and internal bypass circuitry. As an engineer, I understand the whole point of a power supply to be able to handle all of the short term and high frequency needs of the internal circuit being served, and the power supply is replenished over a complete 60 Hertz cycle from the source, which is very slow in comparison.

Low frequency and subwoofer signals are another matter. Here power dissipation and replenishment are taking place at about the same rate. Again however, the power supply designed to help even it all out within the limits of the power amplifier design itself. A 1000 watt amplifier putting out 1000 watts at 20 Hertz is having its power supply capacitors replenished at 6x the rate of dissipation, with a full wave rectifier, so there would be no big peaks involved.

Again, it is the perceived need for high frequency replenishment capability from the source that I am having trouble seeing.

At low frequencies, anything that cannot be replenished at the 60 Hertz rate is beyond the capability of the design.

By the way, your 4 gauge wiring is a good idea.


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## Talley (Dec 8, 2010)

Savjac said:


> Am I reading this right that a 125wpc amp driving 5 channels can do 1700 watts ? At the speaker or how would that work ??
> 
> Just curious.
> 
> Thanks


I had just looked at peak so I'm assuming it was a single measurement... no way was it rms or anything like that.



AudiocRaver said:


> Tally, Thanks for looking at my numbers, I know I went overboard with that , I was curious to see where it went more than anything. Thank you for the correction on the wire gauge and for some real-world measurements. I also kind of question where all that power went but I suppose your sub may have added to it. I agree that the voltage drop at the source is the big thing we are after here ,that was in my analysis but got buried.
> 
> no doubt about it, the power that gets dissipated has to be replenished. I am very curious about how long that 1700 watts lasted. The measurement equipment you are using is certainly capable of measuring fast current peaks. If you are logging at 30 samples per second, that is only once every two cycles for a 60 Hertz source. If I am not mistaken, the question was about AV equipment needing to draw instantaneous peaks of power from the power source and wiring rather than from its own internal supply and internal bypass circuitry. As an engineer, I understand the whole point of a power supply to be able to handle all of the short term and high frequency needs of the internal circuit being served, and the power supply is replenished over a complete 60 Hertz cycle from the source, which is very slow in comparison.
> 
> ...


First off I'm an electrician not an engineer so it's good that we can both look at it. Second I had borrowed that meter and wasn't really familiar with everything and remember just clamping onto the wire and reading the voltage and amperage on the min/max recordign which did peak too. Maybe the peak resolution was higher but I just did simple math and came up with that wattage. Again I need to get that meter back and try again.

Thanks on the 4awg. In all I have 8 circuits at my rack. all 20amp. one is 4awg, three is 8awg and three is 10awg and one is 14awg (this one is dedicated just for my 18watt network 5 port switch lol) Nice for me is the panel is in the unfinished garage that is detatched from the house but is connected together by a covered patio that has it's own attic space and that is where my outlet box is behind my rack... that portion of wall backs into this attic space. 63 feet exactly in cable. I could add another 8 circuits in a day if I needed them.

EDIT: ya forgot about the sub it was on there too, I took the measurement at the main lugs so it covered eveyrthing.


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## Savjac (Apr 17, 2008)

Talley said:


> I had just looked at peak so I'm assuming it was a single measurement... no way was it rms or anything like that.


Thank You Tally for the reply, this is interesting indeed. 
Oh and if you ever want to visit my home and wire me up a couple new dedicated outlets I would be your new best friend :innocent:


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## Talley (Dec 8, 2010)

Savjac said:


> Thank You Tally for the reply, this is interesting indeed.
> Oh and if you ever want to visit my home and wire me up a couple new dedicated outlets I would be your new best friend :innocent:


Now thats something I can do haha. I'd rather just run a larger diameter wire and install a tiny 8 space 16 circuit panel (~12"x12") then you can have whatever you want.

EDIT: it kinda ticks me off that I didn't do this same thing. 8 circuits of large size cable 63 feet or just ONE cable 63 feet. I could of ran a 2/0 feed to a small 16 circuit panel AT my rack... then had flex between my outlet box and that small panel box.

I may change my setup to that. I like that idea better.


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## Savjac (Apr 17, 2008)

Talley said:


> Now thats something I can do haha. I'd rather just run a larger diameter wire and install a tiny 8 space 16 circuit panel (~12"x12") then you can have whatever you want.
> 
> EDIT: it kinda ticks me off that I didn't do this same thing. 8 circuits of large size cable 63 feet or just ONE cable 63 feet. I could of ran a 2/0 feed to a small 16 circuit panel AT my rack... then had flex between my outlet box and that small panel box.
> 
> I may change my setup to that. I like that idea better.


You are the electrician professional, I trust you will do the right thing. 
I may even let you work the controls on my A/V system and listen to different components as you wish.

I am still somewhat flummoxed by electricity in many ways but I can do some basic stuff and may even be able to run a couple dedicated lines as the home theater is above the garage and the garage is where the main box is. I dont think anyone would check but having a licenses electrician would make me sleep better.


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## AEIOU (May 3, 2011)

tesseract said:


> Looks good, Tonto. I am looking for no MOVs, but will keep the APC in mind.


What do you have against MOVs? I have made my own surge/power strips by adding 3 lines of MOVs, adding a fast blow fuse instead of the generic circuit breaker, adding bypass capacitors and inline inductors. I've also added inline EMI/RFI noise filters to specific AC circuits inside my home.


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## AudiocRaver (Jun 6, 2012)

Some don't like the way they self destruct and then you have to repair or replace an expensive piece of gear. I say if it saves your other gear, OK. The Furman designs somehow avoid the sacrificial thing.

Sounds like you came up with a pretty good DIY solution. My Furman strip gave me a nice hiss reduction via one HDMI input to my AVR. I'm a believer in the EMI/RFI filtering.


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## tesseract (Aug 9, 2010)

AEIOU said:


> What do you have against MOVs? I have made my own surge/power strips by adding 3 lines of MOVs, adding a fast blow fuse instead of the generic circuit breaker, adding bypass capacitors and inline inductors. I've also added inline EMI/RFI noise filters to specific AC circuits inside my home.


What Wayne said... MOVs wear out, no longer protect the gear and become a possible fire hazard. Seems Furman has found a way around that.


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## lcaillo (May 2, 2006)

That simply is not true. When MOVs fail, they do fail as a short circuit, but that instantly trips a braker or a fuse. The idea that they lose effectiveness over time is simply not born out by either experience nor any research. I sold and serviced systems with MOV protection for thirty years and never, not once, was there ever a fire due to an MOV and never, not even once was a system that was properly protected damaged by even severe lightning strikes. I did see a number of MOV units with burned MOVs inside, and even a couple that were melted into a blob, but this was because they did their job. I had several that were replaced by Panamax that were totally cooked. 

The problem with MOVs is that it is very hard to test them so you really don't know that they are ready to work. We once decided to test some MOVs in a couple of surge suppressors that had been in a hard lighning stike to see if they were still good. Several were torched and the others, when presented with a spike of over 1000 volts that we rigged up with an old flyback transformer clamped at about 150 volts. I have discussed the matter with many engineers at electronics manufacturers and the more reputable surge protection companies and even the ones who don't recommend MOV protection concede that they are very reliable and effective, and rarely, if ever, fail as an open circuit.

The fact is that MOVs do nothing to degrade any system and only improve protection. There just is not a downside to them. They are cheap and effective. They are not the entire solution to protection and do nothing for noise or power fluctuations, but they are very effective against spikes. Combined with proper grounding, very useful.


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## Talley (Dec 8, 2010)

I'm taking a 4/0 ground from the metal casing of all my equipment to 20 ground rods around the house.... eat that Lightning lol

oh by the way "rarely fail in a closed circuit" open means good for protection.


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## AudiocRaver (Jun 6, 2012)

lcaillo said:


> That simply is not true. When MOVs fail, they do fail as a short circuit, but that instantly trips a braker or a fuse. The idea that they lose effectiveness over time is simply not born out by either experience nor any research. I sold and serviced systems with MOV protection for thirty years and never, not once, was there ever a fire due to an MOV and never, not even once was a system that was properly protected damaged by even severe lightning strikes. I did see a number of MOV units with burned MOVs inside, and even a couple that were melted into a blob, but this was because they did their job. I had several that were replaced by Panamax that were totally cooked.
> 
> The problem with MOVs is that it is very hard to test them so you really don't know that they are ready to work. We once decided to test some MOVs in a couple of surge suppressors that had been in a hard lighning stike to see if they were still good. Several were torched and the others, when presented with a spike of over 1000 volts that we rigged up with an old flyback transformer clamped at about 150 volts. I have discussed the matter with many engineers at electronics manufacturers and the more reputable surge protection companies and even the ones who don't recommend MOV protection concede that they are very reliable and effective, and rarely, if ever, fail as an open circuit.
> 
> The fact is that MOVs do nothing to degrade any system and only improve protection. There just is not a downside to them. They are cheap and effective. They are not the entire solution to protection and do nothing for noise or power fluctuations, but they are very effective against spikes. Combined with proper grounding, very useful.


I am convinced. If it saves my gear, I will sacrifice the MOV and strip. And I will keep my MOVs in a fairly inexpensive strip so if I start to wonder about it after X number of years, I can just replace it. Lightning is no laughing matter! And we get plenty of it in the Midwest!


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## Savjac (Apr 17, 2008)

AudiocRaver said:


> I am convinced. If it saves my gear, I will sacrifice the MOV and strip. And I will keep my MOVs in a fairly inexpensive strip so if I start to wonder about it after X number of years, I can just replace it. Lightning is no laughing matter! And we get plenty of it in the Midwest!


ABSOLUTELY agree, I live in tornado/storm alley here in the Ohio river valley and while I do plug the amp directly into the outlet as per Emotiva personnel instructions, everything else that touches electricity is on the other side of protection. I have been hit by lightening in the past and it put a hurt on everything I had so an expensive lesson we need never have to experience again.
:nono:


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## lcaillo (May 2, 2006)

If I come off as a bit overbearing on the matter, it is because I have researched the technology more than most engineers that work for the companies that make this stuff. I ran shops and did very complex installations in Louisiana and Florida, two of the most likely places to see thunderstorms and lightning damage. In the early days of cable and satellite, and with antennae, we saw lots of damage. So back in the early 1980s I started to get to know the technology and spent lots of time experimenting and talking to engineers. 

What you learn pretty quickly is that what you hear from electronics manufacturers publicly is not always what their engineers know or believe. No vendor wants to admit that anything can go wrong or could be designed differently, and most will tell you what it takes to sell their product. Once you dig deep enough, you can get the rest of the story.

As you know, Wayne, because we joke about it, I am always right because my defualt answer is "it depends". With protection it is no different, and there are always extreme examples of exceptions. With MOVs, however, they just don't have much of a downside. They are ridiculously cheap and the more of them you have in a system the more likely you are to be well protected. The part that depends is how well your path to ground and your neutral hold up in a severe incident. That is why no matter what you do in a system, you must always be grounded to the central ground point of the electrical sysetm. Dumping current through MOVs has to go somewhere...


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## tesseract (Aug 9, 2010)

lcaillo said:


> That simply is not true. When MOVs fail, they do fail as a short circuit, but that instantly trips a braker or a fuse. The idea that they lose effectiveness over time is simply not born out by either experience nor any research.


Thanks for that, Leonard, I did not know.

I did a few hours of digging around internet and it kept coming across that MOVs wear out and when they do, become a fire hazard.

Hence starting this thread. :help:

My biggest issue now is having 3 beefy amps, with a 4th coming soon, an HDTV and all my other gear plugged into the Furman strip that is plugged into the wall. I guess if I am not making the lights dim, I'll be OK.


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## AEIOU (May 3, 2011)

AudiocRaver said:


> Some don't like the way they self destruct and then you have to repair or replace an expensive piece of gear. I say if it saves your other gear, OK. The Furman designs somehow avoid the sacrificial thing.
> 
> Sounds like you came up with a pretty good DIY solution. My Furman strip gave me a nice hiss reduction via one HDMI input to my AVR. I'm a believer in the EMI/RFI filtering.


If an MOV self destructs, it's doing its job! I've seen their viability more than once.
The sky is falling, the sky is falling! No fires. Hey, if a fuse blows don't you replace it?


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