Make-Your-Own Surge Protector

[Jane P.]

I found the following thread on making-your-own Surge Protector on the Casita Travel Forum.

http://www.casitaforum.com/invboard/...showtopic=6952

The poster shows how to make your own surge protector for a fraction of the cost of a new one. If you read through the entire thread you'll see alternate approaches.

I think this is a terrific discussion and wanted to pass it on.

JMP

[Curtis F.]

Thanks.

[Joe Z]

Great link......
I need to make one of these as i have already burnt out two directv receivers from surges and this should be the answer.
Joe

[Bryan L.]

Link is only good if you are a Casita forum member.

[Joe N]

This is a copy of the post on the casita forum for those that are not members over there.

Posted 24 July 2010 - 10:58 AM
I have been meaning to purchase a power line surge protector for our Casita. I am not the type that would dream of plugging a TV or home stereo system into a home plug without some sort of surge protector, but here I am three years into this new camper without any surge protection. Just think what a high voltage spike could damage: converter, refrigerator, AC, sound system etc. Enough to really ruin a trip!

What I wasn't prepared for was the cost of commercial surge suppressors for campers/RVs. It appears that a simple inline protector starts at about $80. Hard wired units that protect against low voltage or power line frequency problems quickly cross $300. These may well be worth the money for peace of mind, but I just want basic protection from over-voltage spikes. Three MOVs (Metal Oxide Varistors), a plug, socket and short section of chord shouldn't cost $80. I went to the shop and found the parts left over from past projects, but since I assume most readers of this Forum are not ham operators and pack rats, I tried to track down a source for these items.

Parts list:

Radio Shack MOVs (part 276-568) about $2 each X3
30 Amp 3 prong female receptacle (Camco) about $6 any RV store
Short 30 amp male molded plug/chord about $10 any RV store

Attached Image: KAMCO parts (Small).JPG


Male Plug and chord and Female receptacle


Attached Image: MOVs (Small).JPG


The three MOVs are mounted across the hot and neutral wire, The hot and ground terminal, and the neutral and ground terminal. All three are needed to protect against common mode spikes (typical of nearby lightning strikes). The Camco receptacle has enough room to hold all three MOVs without any modification.

Attached Image: Labled receptecal (Small).JPG


Finished labeled project


Why would you not want to do this? There is no liability or damage insurance that is typical of commercial products



I got the CAMCO recepectal from Dixie RV in Newport News, VA. It was some years ago for a project I never completed so I guess prices have gone up (high price of plastic I guess).

You could do the same project with a short 30 amp extension cable and a simple 110 volt electrical junction box in the middle. Cut the cable in the middle and mount the MOV's in the box. I was just using what I had on hand.





Not much at drawing schematics, but I copied the installation diagram from the CAMCO unit.

In a perfect world, two MOVs would be enough, but is either the neutral or the ground lead are not functioning, a common mode spike could cause damage.

Attached Image: MOV Placement (Small).jpg


Jeanne & Gil & Oliver
16 foot FD 2007
Rocinante II
2006 Toyota Highlander V6 FWD
Factory tow package
Hensley CUB sway/WDH hitch
Jeanne & Gil & Oliver (the dog that owns us)
-----------------------------------------------------------------------------------------------
This is a copy of Jeanne & Gil's post, for your convenience. I did not make copies of of the other replies.

[Jane P.]

Originally Posted by Bryan L.

Link is only good if you are a Casita forum member.

I believe you can go to Casita Travel Forum as a visitor. Look up "Electrical". then "Surge protector".

BTW, you don't have to own a Casita to join the forum. And ... it's a good one.

[Roger C H]

These aren't so expensive:

DeltaSurgeProtectors.com - Homepage

[Bob H]

For what it's worth, a safe solution for those folk who have sensitive electronics like TV, laptops, radio, etc is to purchase a uninterruptable power supply. Commonly used with computers, a UPS offers surge and ripple protection by actually separating your valuable appliances from shore power, and with it's built in battery back-up, a UPS gives you a few precious minutes of power during outages, to power down safely.

I can't afford one of those high-dollar, built-in inverter type power generators, but by using a UPS as protection, any generator, or other less than reliable or suspect power source is fine.

Happy Campin',
ConwayBob

[Curtis F.]

Originally Posted by Bob H

For what it's worth, a safe solution for those folk who have sensitive electronics like TV, laptops, radio, etc is to purchase a uninterruptable power supply. Commonly used with computers, a UPS offers surge and ripple protection by actually separating your valuable appliances from shore power, and with it's built in battery back-up, a UPS gives you a few precious minutes of power during outages, to power down safely.

I can't afford one of those high-dollar, built-in inverter type power generators, but by using a UPS as protection, any generator, or other less than reliable or suspect power source is fine.

Happy Campin',
ConwayBob

Using a UPS is a good practice. However, a UPS only filters the 120 volt power on it's way to your device. The UPS will sound rapid beeps when it can't handle the 120 volt source power and provide properly filtered 120 volt power. At that time disconnect your sensitive devices and try to find a 120 volt source that doesn't make your UPS beep rapidly. When 120 volt power is lost, then the UPS uses an inverter to convert the stored 12 volt power to 120 volt power. Back-UPS LS - Product Information

It also safeguards your equipment from damaging surges and spikes that travel along utility and phone lines. A distinguishing feature of the Back-UPS LS is automatic voltage regulation (AVR). AVR instantly adjusts both low and high voltages to safe levels, so you can work indefinitely during brownouts, saving the battery for power outages when you need it most.

Don't do as one of my bosses did and turn off the beeps and continue to use his computer while running on a construction grade generator.

[Bonnie n Claude]

We just bought a refurbished 1974 Boler that has no fuses or breaker box. We are going to Texas in nine days and will be running the fridge on 120V along with a small LED light. We have added a 4 cup coffee maker, small microwave and LCD TV (for rainy days) and a notebook computer. Aside from using only one thing at a time and using a computer-type power bar/surge protector is there anything we can do over the short term to avoid electronic problems? (We are having the wiring rechecked in the spring.)

[Bob H]

Originally Posted by Bonnie and Claude

We just bought a refurbished 1974 Boler that has no fuses or breaker box. We are going to Texas in nine days and will be running the fridge on 120V along with a small LED light. We have added a 4 cup coffee maker, small microwave and LCD TV (for rainy days) and a notebook computer. Aside from using only one thing at a time and using a computer-type power bar/surge protector is there anything we can do over the short term to avoid electronic problems? (We are having the wiring rechecked in the spring.)

Assuming you'll be plugging into a standard 120 volt, 15 amp. service when you camp, you have potentially 1800 watts of electricity to work with. From your list of appliances, count on the refrigerator & microwave to draw the most juice. Any appliance with a heater coil (coffee maker) you can count on 200 watts in use. You can see how it all can quickly add up.

The smartest investment is to get load tester. You can get one built-in with its own power strip/surge protector too.

[Bonnie n Claude]

Thanks, Bob. We also have a 33' trailer that's been stationary in a campground for 13 years. The last time we hauled a trailer it was a Lionel tent trailer in the late 1970s so we have a lot to learn about moving about. Will add the load tester and built-in surge protector to my ToDo list and continue reading the posts on this wonderful site for additional recommendations / warnings.

[Jane P.]

Since I started this thread, I'll update you all on my eventual decision.

A brief background: About 18 months ago, I was at RV "service garage" and saw a fairly new Bigfoot Camper. So, of course, I asked the service people about it. They told me that the Camper's appliances and electronics were totally "fried" via faulty wiring at a RV Trailer lot. Everything had to be replaced ($$$$!). That got me thinking seriously about surge protection.

But ... surge protectors are expensive. And when dealing with expensive stuff, I tend to research my purchases.

I was interested in saving money, so I liked the idea of this do it yourself approach.

However, because I have an air conditioner, I needed protection for under voltage as well as power surge problems.

I did learn that Built-in Surge Protectors are not a good idea with smaller trailers. These products are designed with the large RVs in mind. They are expensive, overkill, and will inhibit flexibility.

And so, I decided to go with the Surge Guard portable model #34730: http://www.surgeguard.com/comparison1.html

The price of the "make-your-own" components added up to about $100. And the Surge Guard unit has come down in price dramatically since I first started researching surge protectors.

The best deal I could find was on Adventure RV:
Portable Surge Guard 120V 30 Amp - $219.79

I was worried about theft, and so I also bought a 25' extension cord. http://www.adventurerv.net/advanced_...xtension+cords

There was another thread of FGRV that discussed length of RV extension cords. This informed me that 25' will not compromise the power coming to my Trailer.

Surge Guard does have a lock hasp: http://www.adventurerv.net/surge-gua...p-p-13593.html

But, Casita forum members agreed that this hasp was fairly easy to break open and does alert potential thieves that there is an "expensive" surge protector hooked up to the power box. Because of this, I opted for the extension cord which costs just a few dollars more than the lock hasp. This cord allows me to lock the Surge Guard in my cabin, so I now have complete piece of mind when I am off training.

I have been using my Surge Guard everywhere I hook up. It takes a few extra minutes to get out the Surge Guard and extension cord. Last Spring, I camped at a spot where the power box was fairly far away, and the 25' cord worked great.

I am really happy with the decision.

[steve dunham]

Originally Posted by Curtis F.

Using a UPS is a good practice. However, a UPS only filters the 120 volt power on it's way to your device. The UPS will sound rapid beeps when it can't handle the 120 volt source power and provide properly filtered 120 volt power. At that time disconnect your sensitive devices and try to find a 120 volt source that doesn't make your UPS beep rapidly. When 120 volt power is lost, then the UPS uses an inverter to convert the stored 12 volt power to 120 volt power. Back-UPS LS - Product Information

Don't do as one of my bosses did and turn off the beeps and continue to use his computer while running on a construction grade generator.

There are different types of UPS systems . One uses the battery only as a backup power source, better ones have the battery across the load at all times (or floating on line) which eliminates voltage dips & spikes . Tripp makes a good UPS but they cost more .
The last ones I bought were for an automated assembly line. They were 1.0 KW and cost about $800.00 ea

[Bonnie n Claude]

Originally Posted by steve dunham

There are different types of UPS systems . One uses the battery only as a backup power source, better ones have the battery across the load at all times (or floating on line) which eliminates voltage dips & spikes . Tripp makes a good UPS but they cost more .
The last ones I bought were for an automated assembly line. They were 1.0 KW and cost about $800.00 ea

As the only things in our Boler running off the battery are two small lights and the CO2 detector and we bought battery-operated LED mini-lights and both a battery-operated CO2 detector and smoke alarm we were thinking of not buying a new battery. (We got the trailer last month and there was no battery in the case.) Can't think what possible use it would be. Our main concerns are: (a) tripping the campground breaker when the small microwave is in use and (b) having a power surge fry our wiring, notebook computer or small LCD TV. We don't plan to run the bits and pieces concurrently and have no AC, so am wondering at what point costly surge protection would be overkill. I was thinking that perhaps a simple powerbar from the computer store would do for this first trip. Thanks for your advice!

[Jane P.]

Originally Posted by Bonnie and Claude

As the only things in our Boler running off the battery are two small lights and the CO2 detector and we bought battery-operated LED mini-lights and both a battery-operated CO2 detector and smoke alarm we were thinking of not buying a new battery. (We got the trailer last month and there was no battery in the case.) Can't think what possible use it would be. Our main concerns are: (a) tripping the campground breaker when the small microwave is in use and (b) having a power surge fry our wiring, notebook computer or small LCD TV. We don't plan to run the bits and pieces concurrently and have no AC, so am wondering at what point costly surge protection would be overkill. I was thinking that perhaps a simple powerbar from the computer store would do for this first trip. Thanks for your advice!

Reading your original post, I've concluded that you are worried about electrical problems inside of the trailer. Until you get a fuse box, your best bet is a power strip/surge protector. I'm assuming updating the electronics are extremely high on your to-do list as soon as you return home.

Regarding higher demand appliances like your microwave, TV and coffee maker, you'll need to get an inverter. http://www.google.com/search?aq=f&gc...ower+inverters They are not all that expensive. They will plug into your "cigaret lighter" outlet. Do you have a "cigaret lighter" outlet?

Without an inverter, your appliances won't work.

Personally, I'd replace your coffee machine with something that will work with or on the propane stove. I have a french press, which works great. I also have a malita (hand drip) coffee carafe. Both of these appliances require hot water - no electricity! Several FGRVers have stove top Italian Coffee Makers or plain old camp fire peculators. You also might want to consider packing a small, propane powered BBQ to use instead of the microwave. I'm suggesting this as a way to bypass electricity until you rewire your camper and add a fuse box.

I'd also use the (please purchase one) inverter to recharge your notebook PC in your car. Then you won't have to plug it into your trailer.

After you get some of your initial trailer purchases behind you, you can consider how important it is to protect yourself against electrical problems originating at your camp ground's hook-up box. Because you don't have an AC, the do-it-yourself surge protector should work well for you and save you $$$.

Think of the money it will take to replace your refrigerator. Compare that with the $75 cost in supplies to build a surge protector.

Having said all that, you don't have to get a surge protector immediately. Yes, you are taking a chance every time you hook up. But that doesn't mean that you camp site will have bad wiring. Take care your your internal wiring. If there are other things you need to do with the traller like ... fix some leaks, install a heater ... the surge protector can take it's place on your to do list.

Good luck with your decisions and ... have a great trip!

[honda03842]

Though the past is not a guarantee of the future, it is certainly an indicator.

In the last 11 years we have camped between 2 and 3,000 nights. We have not once had an electrical failure while camping due to voltage spikes, lightening strikes, or campground wiring.

We do NOT have a surge supressor.

We do have two 100 watt Cigarette Lighter Inverters. We keep one in the Tow Vehicle and one in the trailer. The one in car is sometimes used to charge the computer but more often to charge our cell phones that we forgot to charge the night before.

On the other hand we did have a laptop charger blow out in the house last summer simultaneously with a lightening strike. It's always smart to unplug expensive electronics during lightening storms, even with surge protection.

[Bonnie n Claude]

Originally Posted by Jane P.

Reading your original post, I've concluded that you are worried about electrical problems inside of the trailer. Until you get a fuse box, your best bet is a power strip/surge protector. I'm assuming updating the electronics are extremely high on your to-do list as soon as you return home.

Regarding higher demand appliances like your microwave, TV and coffee maker, you'll need to get an inverter. power inverters - Google Search They are not all that expensive. They will plug into your "cigaret lighter" outlet. Do you have a "cigaret lighter" outlet?

Without an inverter, your appliances won't work.

Personally, I'd replace your coffee machine with something that will work with or on the propane stove. I have a french press, which works great. I also have a malita (hand drip) coffee carafe. Both of these appliances require hot water - no electricity! Several FGRVers have stove top Italian Coffee Makers or plain old camp fire peculators. You also might want to consider packing a small, propane powered BBQ to use instead of the microwave. I'm suggesting this as a way to bypass electricity until you rewire your camper and add a fuse box.

I'd also use the (please purchase one) inverter to recharge your notebook PC in your car. Then you won't have to plug it into your trailer.

After you get some of your initial trailer purchases behind you, you can consider how important it is to protect yourself against electrical problems originating at your camp ground's hook-up box. Because you don't have an AC, the do-it-yourself surge protector should work well for you and save you $$$.

Think of the money it will take to replace your refrigerator. Compare that with the $75 cost in supplies to build a surge protector.

Having said all that, you don't have to get a surge protector immediately. Yes, you are taking a chance every time you hook up. But that doesn't mean that you camp site will have bad wiring. Take care your your internal wiring. If there are other things you need to do with the traller like ... fix some leaks, install a heater ... the surge protector can take it's place on your to do list.

Good luck with your decisions and ... have a great trip!

We once had a summer cottage burn to the ground so yes electronics are really high on my priority list. The trailer does not have a 12V outlet. It does have three 120V outlets which are connected in a daisy chain (the main power source attached to the first one, the second outlet wired off the first, etc.) We had it looked at and were told the wiring appears to be quite new. When we return a friend who used to build trailers and who runs a trailer repair service for campgrounds will do an inspection and tell us what we need and in what order--from a safety standpoint--we should do the work.

I did buy a power inverter for the Dodge Caravan but it won't be much use in charging things once we setup in Texas for 4-6 weeks. We have taken it to Quebec City for a weekend trip and the coffee maker and small cube space heater worked fine on the 120V. I would have used just a filter holder and a cup to make coffee but my husband claims it isn't hot enough when it's done and he doesn't like warmed up coffee. Happily he only drinks once mug a day. (Shame to waste the counter space for the 4-cup coffee maker, eh?) We bought a small Weber BBQ and a Coleman Sportcat heater. I am vegetarian (oddly so was the previous owner) and eat raw foods or "zapped" stuff when it's cold out. We may regret installing the microwave but at home and in our Glendale (parked in a campground for the past 13 years) we use the microwave daily. In preparing our wishlist we looked at what we do on a day-to-day basis and tried to eliminate all the STUFF that has crept into our lives.

Will check on the surge protectors when we're Stateside and will look up the do-it-yourself version.

What a difference going from a 33' (stationary) trailer with a slide-out and all the amenities to a 13' trailer we plan to tow! Naively we thought we'd buy it, hook it up and go. Great learning experience! Really appreciate all the comments folks have posted on this site as it has helped enormously.

Bonnie

[Bonnie n Claude]

Originally Posted by honda03842

Though the past is not a guarantee of the future, it is certainly an indicator.

In the last 11 years we have camped between 2 and 3,000 nights. We have not once had an electrical failure while camping due to voltage spikes, lightening strikes, or campground wiring.

We do NOT have a surge supressor.

We do have two 100 watt Cigarette Lighter Inverters. We keep one in the Tow Vehicle and one in the trailer. The one in car is sometimes used to charge the computer but more often to charge our cell phones that we forgot to charge the night before.

On the other hand we did have a laptop charger blow out in the house last summer simultaneously with a lightening strike. It's always smart to unplug expensive electronics during lightening storms, even with surge protection.

Thank you! That is very reassuring. We don't have any 12V outlets in the Boler but can, in a pinch, use the inverter we bought for the van.