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JJH3rd · 01-16-2012, 02:11 PM

Folks,

After having a near miss lighting strike and replacing the TVs, the microwave control panel and repairs to the inverter, I decided to install a surge suppressor on the shore power cable.

I purchased a Progressive Industries Smart Surge 50 Amp and considered my installation options.

The surge suppressor is set up to plug into the shore power outlet and have the RV’s power cable plug into the surge protector. I have a problem leaving the surge protector outside where it could sprout legs and walk off so I worked out how to set it up so that the unit is inside the hatch with the transfer relay box.

I had to be careful to keep the correct sequence so that the two hot and the common circuits didn't get swapped: RV transfer box => 50A plug => surge suppressor => 50A socket => shore cable => 50A plug => shore power scoket.

This meant installing a plug coming out of the transfer switch box (wired EXACTLY as the spike & bayonet socket on the side of the RV) that plugs into the surge protector. It also meant installing a 50A socket in place of the spike & bayonet plug on my shore power cable. This meant several trips to the orange or blue big-box electrical departments.

I was fortunate that when I removed the plastic hole insert in the electrical/communication hatch, the outlet box fits through the hole so if needed I could extract the entire 50A power cable.

The dummy or extra socket holds the plug from the transfer switch circuit when the surge suppressor / shore power isn’t in use. I didn’t want to disable the wiring from the factory installed socket on the side of the RV but I didn’t want a potentially live plug with big blades hanging lose in the hatch so a dummy socket seemed the simplest way to secure the plug.

I have the RV plugged into shore power all the time and so far this setup seems to work just fine.

Bill WA6YBD · 01-16-2012, 04:32 PM

Hi,

I understand your concern about theft of the surge protector but my concerned about the safety of your installation. What you have built is what they call in the electrical world a "Widow Maker". From what I read is, you left the original AC inlet connector on the side of the motor home connected along with your new wiring at the transfer switch. So does this mean it is also hot whenever you are using the new surge protector circuit? If so, you have created another widow maker on the side of the motor home. I think it would be possible to expand on your idea and install the surge protector in line with the feed coming from the original AC inlet on the side of the motor home but ahead of the transfer switch. When I installed my AC power cord reel I opened the transfer switch and disconnected the wires from the side inlet and connected the power reel at that point. The wiring to the inlet is still there just not connected in the event I need to remove the power reel I can reconnect them. From what I remember it would be easy to splice in some wires and run them to the surge protector and then run another set of wires from the surge protector back to the transfer switch. Simply stated it would be putting the surge protector in line with the original factory wiring on the side of the motor home. This would also eliminate both widow makers. You have enough material available to do this without having to go back to the store. Perhaps you could mount your current dummy plug on the side of the transfer switch and connect it to the wires that come from the original inlet on the side of the motor home. You may have to extend the original wiring but it should be simple. You would now plug the surge protector into the new plug and then connect the pigtail that you have already installed into the surge protector. You would now use your original AC cord and side inlet, the protector is always in line, it is hidden from site and there are no widow makers what so ever.

You could also simply disconnect the wires coming from the original side inlet inside the transfer box, wire nut or tape them off and let them float inside the transfer switch housing. This would eliminate all potential danger and require the minimum amount of rework. If you must keep the side inlet hot please take a pair of channel locks and cinch up the cap so it is not easily removed. You do not want some kid to get hurt playing around a hot circuit.

Don't want to rain on your parade just concerned about safety.

By the way I love your motor home. We have the same make, year, model and paint as yours. Must have something to do with ham radio.

73 ~ Bill

JJH3rd · 01-16-2012, 11:18 PM

I wrestled with the issues you have raised and I believe that I have come to acceptable compromises.

First I thought about cutting and taping the leads from the external socket to the transfer switch. The problems with that solution are: it would significantly change the manner that shore power connects to the RV (& perhaps effect future sale-ability), and if someone else used the external socket expecting it to be “live” would there be a fire/shock hazard from the clipped ends?

You will note from the image that there is a cover on the socket. It has been taped closed so that the connectors will not be accidently accessed.

The dummy socket “should” be just a belt and suspenders precaution. The only time the new plug from the transfer box “should” be hot is when it is connected to the surge protector and thus to shore power. When the Generator is running, theoretically no power is present on the shore-side of the transfer switch – but even it is it is the plug will be safely plugged into the dummy socket.

A reel for the shore power cable would be a good idea but I still want to have the surge protector behind a lockable hatch and in the correct sequence.

I appreciate your concern. While rewiring old houses, more that once I’ve been surprised to find power in what I thought was a dead circuit.

Thanks for the suggestions.

Gary RVRoamer · 01-17-2012, 09:33 AM

It's water over the dam now, but wouldn't it have been smarter/easier to buy a Surge Guard "Hard Wire Plus" transfer switch with the surge & power monitoring built in, or one of the permanent mount versions of Surge Guard or Smart Surge? The Hard Wire Plus would have eliminated the Widow Maker as well as the extra gear lying in the rear compartment.

Surge Guard® | Technology Research Corporation

Bill WA6YBD · 01-17-2012, 09:45 AM

Hello again,
I now see the cover over the outside inlet. I thought that looked a little different then what I remembered. What I was suggesting is similar to what you have already done with only one exception. All the components would stay inside the compartment as per your requirement. And with the cost of the protector I totally understand. The difference with my suggestion is listed below.

The new receptacle could mount to the wall right next to the AC transfer case. The original AC input to the transfer relay would be moved to the new receptacle mounted near the AC relay transfer box. You would have to cut a hole in the box and bring the existing wires out. If the wires are not long enough it may require extending them slightly. Next; the surge protector would plug into the newly installed outlet connecting its input to the original AC inlet wiring. Next; the pigtail and plug you have already installed would plug into the surge protect just like you have it now completing the circuit. I have attached a block diagram for clarity.

The surge protector is removable for service or bypassing. Simply remove the protector and plug the your pigtail into the new receptacle. With my solution you would still have to use the original AC inlet on the side of the motor home. If your intent was to not have the power cord hanging down on the side of the MH then your solution works perfectly. I must admit I did not like having the cord hang down the side of my MH. This is the only difference between the 2 approaches and with my solution there are no widow makers.

When I mentioned that I had installed a power reel I should have been more clear on that. I meant I had been inside the AC transfer case and knew what it looked like and that I disconnected the wires from the original AC inlet so as not to create a widow maker. I was not suggesting you should install a power reel. However they are the greatest thing since sliced bread. I got mine on ebay for $250.00. The best $250.00 I have ever spent but I am getting off track. If I should elect to sell the coach and want to remove the power reel it would be very simple to remove and reconnect the original wiring.

As per all projects there are many ways to skin a cat.

Thanks again for taking the time to listen to my approach and concerns.

Hopefully we will cross paths someday either on the road or on the air.

73 ~ Bill WA6YBD

JJH3rd · 01-17-2012, 11:08 AM

At the time I started this project I really didn't want to spend $200 => $350 on an inline device, so I went with the plug in model, which led to the outcome I've shown. Another consideration is space on the walls of the box and the configuration of the transfer box and the wiring into and out of it.

Yes I agree that now that I have things working I will work on securing the boxes to the walls. One way or the other I'll need a pig tail: either between the shore cable and the surge protector or the transfer box and the surge protector (or perhaps both).

One of the goals was to eleminate the 90 degree strain on the shore cable when it is plugged into the wall mounted external socket. Over time the external insulation has a tendency expose the wires leading into the spike plug and instead of adding some kind of strain relief to the outside of the RV, I thought a better solution was to move the connection point.

lenjen · 01-19-2012, 04:10 PM

Hi JJ, I came on today to find out how many members use Surge Guards. My FIL gave me a 50 amp one for Christmas plus the locking case, most of the time I am in sites that only offer 30 amp services so I use a short reducer on the coach then use my 30 amp cord. I may start a thread to see what others are doing as I am not technical enough to understand your system even after seeing it.

wa8yxm · 01-20-2012, 08:50 AM

What you need to do is take a look at this product.
Hughes Autoformers Installation Kit For 50 Amp Autoformer

I personally think the Kit is over priced, and built my own from stuff I got at Lowes.

IT not only works for the Hughes autoformer, but for your surge guard as well, and wha'ts more you can chain both of them.

Advantage not noted is if you upgrade to a bigger and newere rig... you pull two plugs, plug one plug into the other socket, and put a new install kit in the new rig and keep your existing guardian.