Whole house Surge Protector

[eepete]

You just need one suppressor for the whole house even if you have a bunch of panels. You _can_ add more, and then you can take a little big bigger wallop but it's not 2x since the MOVs between units are not matched so they won't be able to cleanly split the load.

I have 3 sets of MOVs, but I like overkill. One set on the panel before the transfer switch, and then the others are in two panels. I also have a MOV across the 240 (i.e. not to ground), but that's for a mix of spikes eating and X10 cross phase coupling.

I also have a suppressor at the generator. Since it is outside on a pad, if there was a nearby strike the ground (and therefore the pad and therefor the AC lines from the generator) could bounce around a bit. At the other house, I had a strike close to the house. It popped the fuse to the MOV at the generator. It also popped the protection on the start circuit, which was OK and far better than frying the electronics at the generator and transfer switch. BTW, this was the bolt that took out my PBX I talk about in my previous posts. Sometimes this protection stuff is a leason in how paranoid do you want to be :laughing:.

While there is a little bit of inductance in the breakers, it's nothing compared to the inductance of all the wires. So any spike that makes it into the house will be eaten by the protector no matter where it is, and the other panel(s) will benefit from this too.

Zick: That unit you posted a link to will do just fine.

Pete

 

[ronjhall]

Eepete, thanks for breaking it down to understandable terms, excellent! I now feel more confident when comparing surge protection. (Now is a good time to install the extra grounding rod after the 5"rain.)

Ronjhall, how would I determine if it was a spike or a low voltage incident?

Would a low voltage cause the ac blower motor to go bad and the new electric dryer not to work? I know for sure the dryer was not on during the storm only plugged in. (still waiting for the dryer repairman)

Do surge protectors protect against low voltage, if not what does?

Low voltage will not harm a motor if it is not on.
AC blower motor could have been on. My blower motor is a variable speed. Forgot the technology, but has a electronic control for the speed. It would not like a spike on the line.

 

[kennyd]

You just need one suppressor for the whole house even if you have a bunch of panels.

Thanks Pete:thumbsup:

 

[Zick]

Thanks Pete:thumbsup:

Agreed, thanks Pete!

 

[txdon]

The appliance repair man came out today and the electronic board on the dryer was bad, we saw no visual burns. I also discovered the breaker at the pole that goes to an outbuilding had been tripped and at the outbuilding the breaker to the AC window unit was tripped (all the other breakers were turned off) I think my outdoor patio breaker (not on the house breaker) at the pole also got some of the spike because now the GFI outlet will not reset.

At the pole I have a 200 amp breaker and then breakers for the garage, "shack in the back", pool pump and patio outdoor lighting outlet (GFI), and then it passes through and underground to the main house breaker.

My question now is should the whole house surge protector be at the breaker box on the pole (where it will also protect the other four breakers) or at the breaker box at the house, or both?

The Electric Co-op came out and looked at the transformer and incoming wires and said they looked in good condition and will deny any claim I file with them. They do not have or offer surge or spike protection. They said it was probably cause by a lighting hit on their wire anywhere within about 5 miles.

They will also check their records to see if they registered a spike in the lines near my house.

 

[SpringHollow]

I would lose equipment from lightning strikes all of the time. I installed the whole house surge protectors maybe 10 years ago and have not lost anything since. I highly recommend them and bought them for my family members as well. They are quite easy to install. Mine was relatively small and cost ~$90. The one at Home Depot that i just bought for the barn are $50 but larger in size.

Ken

 

[eepete]

txdon, my gut feel on where to put a protector is to put one in any box that has it's own ground connection to a ground rod. If you put on at the 200 amp breaker at the pole, and then the panel at the garage has it's own ground rod, then a strike in that area could elevated ground potential a bit and your shop would be at risk. Sounds like the units SpringHollow found at Home Depot for $50 would be good.
About the only way to compare units is the silly marketing Joule rating. If you can find a beefier and more expensive unit, you might consider using that at the house and smaller ones at your other locations. I guess you just have to think about these protectors as a one-time payment insurance policy with limited coverage :laughing:.

I'm going to stress that this is gut feel. My outbuilding garage gets it's power via buried conduit from the main house. It has it's own ground connection, and the rebar in the slab also connects to that ground. So the panel in the garage has it's own protection.

The electric co-op statement that the strike could be anywhere on distribution network within a 5 mile radius is very true. These are the things that create spikes that the protectors can handle. If you have arial distribution to your house and take a strike there, the protector won't cut it and we're back to insurance (and maybee your local fire department) as your last "stage of protection". This is also why they looked at your drop and transformer at your pole.

I've incurred extra cost and grief to have buried service to the house. Part of the reason for that is to reduce the chance of a hit on the 240 coming in and reduce the chance of a bad strike.

Pete

 

[SPYDERLK]

Very good cogent explanation EEpete. I missed the below typo in my 1st read. I know you know it, but some trying to understand may hit it as a roadblock.
larry

An MOV is a Metal Oxide Varistor. It came about in the 1930's or so, and GE made great strides in mass producing them during the 1950's at the Schenectady NY facility. Companies all over the world make them now. The MOV is placed from the line being protected to ground. When the voltage across the MOV reaches a certain level, the MOV start to conduct current. This process is pretty abrupt, and happens instantaneously. A MOV that is happy seeing 130V AC across it can start to conduct around 150V and by the time the voltage is up to 300V it wants to conduct hundreds of amps. This is how it "eats" the spike and shunts it to ground. Now if you do the math, think about this poor little 1 inch disk (about 1/8 inch thick) with 300 volts across it and 100 amps going through it. That's a peak power of 30,000 watts. Sure looks like a job for a 20,000 joule device. So if the device can conduct that 30,000 watts for 100 microseconds (about the time of the peak ringing of a lightning induced fault), then the actual work or heat dissipated by the device will be about 3 watts[[Joules]]. The disc will quickly heat up, then cool down, and survive the event.

Hope my too long explanation helps, if you've got more questions ask. If you look again at the picture from NSbound, it will make a lot of sense now. Looks like a good unit to me!

Pete

 

[mikim]

ya know don --- I am so glad you built your house first -- need to make some changes on my drawings now.

 

[txdon]

Well, after complaining to the electric co-op yesterday that if they promote new energy saving appliances they should be able to supply a way that their supply will not knock out the new micro computers, I woke at 5 AM up to NO POWER at all to the house. I drove about two miles down the road and the person I complained to was on the side of the road with his big truck. Last night a line just burned up and cut power to this end of the county. We are back up now!