Surge protector, roll your own

[Pagan]

There have been some seriously heated discussions about surge protectors. Personally, I feel they are a small part in overall electronics protection, and aren't much good at much more than providing a bunch of convenient outlets. Good grounding is an absolute must, with a direct circuit to the breaker box if possible.

As for the circuit breaker, that will do a fine job in protecting the wires, but it adds no protection to anything else hooked up to it. Better protection would be provided by a fuse, fast or slow blow depending on your equipment. It's more of a hassle, but it'll be a lot faster than a circuit breaker.

Pagan

[Rob Mills]

Been snooping around and notice that the cheap (office depot and etc) plastic strip (5 recep) surge protectors have only one MOV but the more expensive ones have one MOV at each receptacle. Looks to me as if you could use metal recep boxes that would hold two or three receps and place a MOV across each recep, put a metal cover on it and a short 3 wire 12 gauge cord and have a much better surge protector to protect sensitive equipment for not much more than the computer/office stores want for the plastic cased ones. I have found MOV's rated at 150 volts and 80 Joules at this web site for $3.81 each,

Any Thoughts?? RM ~

PS, Think I would put a 15 amp push button circuit breaker on the box

[SQLit]

Your correct. However 80 joules is not a lot of power. My surge strips are rated for 300. My whole house protector in the panel is rated for 1500 with a let through of 300. So far the combination has worked to keep everything safe.

You might want to read this page

If your serious about surges then read some of the information by Mike Holt.

[CL (dnoyeB) Gilbert]

Fuses are circuit breakers are the same type of device for generally the same purpose. They protect wiring. For protection of equipment and people you use a different type of device. Thus the CB is of no use.

As for making your own surge protector, go for it. But I hope you know all the ins and outs and don't put yourself or your family or your equipment at undue risk.

[Bob S.]

What's wrong with pulling the wall receptacle and placing a MOV across the hot/ground terminals? Gets rid of the ugly box, protects anything plugged into it plus down-stream receptacles. Of course you'd have to remember where it was in case it ever shorted.

Bob S.

[Tony Hwang]

Hi, Joule is not a measurement of power it is unit of energy. Let me put it this way, if you get a direct hit nothing uch will work. Telling from real world experience. And real protector for whole house costs a lot. And surge current is much faster than breaker or fuse. Tony

[Rob Mills]

[w_tom]

You are assuming the MOV is the protection. How? What will that MOV do? Absorb the surge? Block it? Since that MOV is so far from earth ground, AND because it is so close to transistors, then it provides the same ineffective protection provided by power strips.

Furthermore, if those $0.10 parts were so effective, then they are already inside the appliance. Anything that is effective on an appliance power cord is already inside the electronics.

How do effectively protected sites do it? Let's take a telephone Central Office computer - connected to overhead wires everywhere in town. They put the connector directly on earth ground AND up to 50 meters distant from the computer.

No earth ground means no effective protection. Those MOVs inside a plug-in box or inside the wall receptacle are not effective.

D> I guess in theory it should work but after seeing one office depot

[w_tom]

Learn by building a protector. Notice what the competition is doing. First, parts cost on the order of $0.10. So how many joules did they install? Why so little cost of parts and yet so such a high price for the protector? Second, minimally sized 'whole house' protectors cost under $50 for over 1000 joules. You may save money by purchasing a 'whole house' protector only to remove its MOVs.

Consider safety - UL1449 2nd edition. One trick is to put inductors in series with the MOVs. Therefore pulse rise time is not as sharp; MOV less likely to vaporize; more likely to pass the UL1449 test. (Others assume that the inductor provides additional electronics protection.) Build it. Its a great way to learn how protection works. You will not save money. You will learn.

The 15 amp circuit breaker is required for human safety when a s> Been snooping around and notice that the cheap (office depot and etc)

[w_tom]

[w_tom]

[Red Cloud®]

It might help if you had some clue as to how an MOV works. And they DO work.

rusty redcloud

[CL (dnoyeB) Gilbert]

For the record, Power is energy over an amount of time. Its measured in Watts which is the same as one Joule per second.

[CL (dnoyeB) Gilbert]

While I agree that surge protectors are not very effective, its mostly because they are poor quality devices. You can find a good quality surge protector. You need to know what size surge you intend to protect. A device can call itself surge protector if its only protecting a surge the size of say, the vacuum cleaner motor. Or even less.

w_tom wrote:

What do you mean here? They use 2 ground lines? There must be a + and

-. One can not be grounded. Please explain what 'connector' is?

The MOV just needs as good or better path to ground than the device it is protecting. The distance is irrelevant.

[CL (dnoyeB) Gilbert]

circuit breakers/fuses protect wiring (and by doing so protect from 'thermal incident' so I'm not disagreeing with you) GFCI protect humans Surge protectors/noise surpressors/filters/etc. protect devices

[w_tom]