Belkin isolator surge protector? Calculating Joules with amps or watts?

[robbyrob]

Just wondering what people think of the Belkin isolator F9A1033-12? http://catalog.belkin.com/PureAV_detail.process?Product_Id=163009

I read other posts in this forum that recommended the F5C980-TEL so I'm hoping that the above is just a newer version. Anybody have good/bad experiences with the Belkin Isolator line?

The F9A1033-12 is rated at 4720 Joules of protection so I'm sure that it will be sufficient for my receiver, subwoofer, TV, DVD player, etc... but I am curious as to how one would calculate the required value. The sales guy at the store simply said that he would recommend at least 2000 Joule protection. Also, is it better to plug the subwoofer into a different outlet or power bar?

If I look at the back of a typical receiver I see a spec section which reads:

120 VOLTS, 500 WATTS, 630 VA (volt amps), 60 Hz

Can I use some of this information from my various components to calculate the sum of Joules? I found somewhere that:

1 watt = 1 joule/second

Also, in my house there is a single 15 AMP circuit that powers all of the wall plugs and lights in the room that I plan on using for the HT. Is this sufficient for a typical HT? I do notice that the lights dim when I turn on the vacuum. I was thinking that if I sum up the amperage of everything on the circuit and it's lower than 15 then I should be okay.

Thanks, Rob.

[WMcD]

The "joule" rating is the amount of power in the spike (presumably caused by a lightening strike on the line) which the unit will dissipate. So it is probably shunting 4720 joules to ground (actually by clamping the voltage to 150 volts or so) before the spike vaporizes the protection device.

So this really has little to do with the power you can draw though the device from the a.c. mains.

Of course the power rating is important. I see there is no such wattage listed but there is often a circuit breaker somewhere in such a strip. You should indeed add up your power requirements to see what you've got. You may indeed be exceeding the circuit breaker for the room in the circuit breaker box.

Gil

[Islander]

Yes, it is better to plug the sub into a different outlet, or even a different circuit if your home's electrical layout permits it. If the sub has a Class D amp, it may put some electrical noise into the line, so it's better if it doesn't share an outlet with your receiver. If it doesn't share a circuit with your computer, that will also be likely to reduce noise.

You definitely don't want to try to run more than 15 amps on a 15 amp circuit, or you'll be tripping the breaker or blowing the fuse. 15 amps on a 120-volt circuit equals 1800 watts, so you should be sure the current draw is below that, leaving some room for the higher momentary draw of musical peaks.

[Islander]

That may have been ambiguous. It's best to put as few electrical and electronic devices as possible on the same circuit as your receiver. Some items that will put noise into the line include your subwoofer, computer, fridge and dishwasher, for example. A surge bar with noise filtering will help.

[Arky]

Not as eloquet a response as these guys but i'm using the F5C980-TEL without issue.

[robbyrob]

Thank you all for your replies!

Just another question regarding circuit noise. Are all of the circuits that run from the circuit breaker separated from each other in terms of electrical noise? The reason I ask is because I can plug in the receiver on a different circuit than my computer for instance, but since they're both coming from the same circuit breaker then they're still linked. It's a different loop though so I see what you're saying but I just want to confirm.

Is it correct to think of it as series circuits coming from the circuit breaker?

[Guest " "]

Thank you all for your replies!

Just another question regarding circuit noise. Are all of the circuits that run from the circuit breaker separated from each other in terms of electrical noise? The reason I ask is because I can plug in the receiver on a different circuit than my computer for instance, but since they're both coming from the same circuit breaker then they're still linked. It's a different loop though so I see what you're saying but I just want to confirm.

Is it correct to think of it as series circuits coming from the circuit breaker?

With one exception, the service box, or circut breaker panel does not provide isolation of the various circuts that run from it.  

Sometimes there is an improvement by using a different line from the service box, but that improvement is not due to the concept of each line being isolated or seperate.

In the US, 220 volts enters the home from the local step down transformer.  At the service box, the 220 is wired as 120 - 0 - 120.  Tipically a red phase and a black one.  If you need 220 for air conditioners, electric dryers, etc, the nearest outlet would be wired across the red and black, if you need 120, the nearest outlet will be wired with either the red or black.

Now, if you have a noise generating appliance or device on the black phase, all runs in the house on the black phase will be exposed to the noise.  To get away from noisy appliances on the black phase, you would have to plug your equipment in an outlet that uses runs on the red phase.

So basiclly there are really only two isolated 120 circuts in your whole house, a red phase and a black phase. 

[Arky]

That's a great explanation Fritz, thanks.

[WMcD]

To expand a bit on S.F. (and I'll defer to his greater expertise).

Yes, on a given phase of service, all the loads are essentially in parallel. You asked about "series". The service within the house on a phase are like extension cords. And when you have a power stip or "tripler" that too puts things in parallel.

It is interesting that some of our audio knowledge applies to the issue of connecting across the two phases to get 240 volts, when each is 120 volts above neutral (which should be zero volts).

At any given electrial outlet there is a "hot" and a neutral. The hot has a sine wave of 120 volts (rms) at 60 Hz. The neutral is, of course zero volts and the current flows back through that. Modern systems have the third wire as a ground but it is not supposed to carry any current in normal operation.

When there is two phase service into the house, the two "hots" are again 120 volts rms volts but the sine waves are 180 degress out of phase. This is to say one sine goes up while the other goes down.

In listening to sound, we have all read that sound wave 180 degress out of phase will cancel. That is true because out in the air, they are summed at our ears.

But when we connect the air conditioner or stove across the phases (each 180 degrees out of phase from the other), the electrical device responds to the difference in voltage. So you get twice the voltage. This difference issue is also true when you plug something into a wall socket where the device is connected to 120 volts minus zero; i.e. the difference.

In house system where you have two-phase service, this often shows up at the circuit breaker box. There are two columns of circuit breakers. The ones on the left are connected to one phase, and the ones on the right are connected to the other.

- - - -

Overall, we all start studying electricity with direct current (d.c.) which is a constant voltage. It is good for basic concepts. Then we get to alernating current (a.c.) circuits where phase becomes very important.

Gil

[ByteWrangler]

...

In house system where you have two-phase service, this often shows up at the circuit breaker box. There are two columns of circuit breakers. The ones on the left are connected to one phase, and the ones on the right are connected to the other.

...

Gil

Most of your post is close, Gil, but not that part. In most (probably all) two-phase panels (breaker boxes) the two phases are connected to alternating breakers in each column, not one phase per column. 220V circuits use pairs of breakers adjacent to each other, usually "ganged" so that when one breaker trips it also opens the other, killing both "hot" phases.

For safety reasons, don't count on that always working, though. If you have a "dead" 220V circuit, one of the phases may still have 110V on it! We had a clothes dryer that would occasionally trip one of its breakers, but the other phase was still live and the 110V motor would continue to run (Murphy's Law requires that it be connected to the live phase), but the 220V heaters didn't work. We'd notice that the dryer was still running after several hours, but was stone cold when we checked it; it would work after resetting the breakers. After a few occurances I replaced the ganged pair of breakers and that cured the problem. Apparently one of the old breakers was weak and would trip way too soon, but not with enough force to open the other.

[WMcD]

I stand corrected by one with superior knowledge.

I hope no one experimented based on anything I wrote.

BTW, since you say most of my post is "close" are there other errors? Smile?

Gil