RV Electrical Fire (Almost!)-> Our Automatic Transfer Switch Failure & Replacement
It all started with an electrical burning smell which, as those of you who have ever experienced it know, is a rather distinctive odor. It’s a sign that something is seriously wrong with your electrical system. Either wires are loose or wires are bare, or wires that are not supposed to touch are touching, or the system is being overloaded, and/or something is melting/burning. Either way it’s one of the scariest things you can experience in an RV and it’s not something you want to mess with. Electrical fires TRAVEL and they travel FAST, and it doesn’t take long after one starts before your entire coach is a goner. If you ever smell that smell, get you and your furry family outta there & turn off power to your coach ASAP!
And so it happened to us.
Now we’re no electric newbies and we are actually pretty careful about our electricity. We carry (and install) a big surge protector everywhere we go, and we regularly check our main panels for loose connections. We really thought we were being pretty diligent, but obviously we were not being diligent enough. There are so many wires in an RV that sometimes you don’t catch them all. And, as is typical in cases like this we think multiple things went wrong before the burning smell finally happened.
Thankfully we were in the coach when it occurred, Paul caught the smell right away and we tracked it down immediately to our Automatic Transfer Switch. So, honestly it was a minor issue that was easy to resolve. But since it happened to us, it could happen to you. So in the spirit of sharing our lessons learnt on the blog here’s a run-down on what an ATS switch is, how it works, what we think might have caused ours to fail and how to avoid this happening to you.
For those that prefer video we made a video! Also, this will actually become a 2-part post/video since we decided to upgrade our surge protector (something we were planning to do anyway) at the same time, so look out for that 2nd part soon. Click the video to see our mugs in living color or just read on below…
What Is An Automatic Transfer Switch?
So, first question you might ask is what in the world is an Automatic Transfer Switch (ATS)??
Well, in general terms a transfer switch is simply a 3-way switch that switches between two input loads to power one out output load. It can be manual (= you have to flip the switch to select the input) or automatic (= the switch automatically selects the input for you).
In an RV an ATS is typically used to switch between generator and shore power so that you can power all your house AC stuff. Only one input can run at any one time, so RV ATS switches are usually “generator-prioritized” which means they’ll prioritize your generator if you’re running that, but will simply use shore power when you’re not. Since they’re the automatic kind, the switching happens without you needing to do anything. So you don’t have to think about which power source you’re using or flip any switches, or plug or unplug anything. It just all happens automatically through the ATS.
There’s a bit more to RV ATS switches (e.g. built-in delays so that your generator doesn’t load right away, less noise from switches that have DC powered contactors versus AC powered contactors etc.), but understanding that it’s basically just a switch that decides between two AC inputs is good enough for most folks.
Note/ Your ATS has nothing to do with your house batteries or your DC systems. It’s just a switch that decides which power source to use for your 120 volt AC systems.
Does Every Coach Have One?
No, not all coaches have them. Older & smaller coaches/trailers generally don’t. Larger, newer rigs and Class A’s, especially those with built-in generators almost always do.
How Do They Go Bad?
There’s many ways transfer switches can go bad. The switch part can manually get “stuck”, wires can get pitted, corroded or come loose, the internal solenoid can fail and/or the system can get overloaded.
Loose wires and corrosion are fairly easy to spot if you check your ATS box regularly and it’s a good thing to include this in your general yearly maintenance. With all the bumping and rocking we do when we drive our RV houses, loose wires can easily happen!
Overloading can happen many ways, but in an RV it often happens from a power surge or plugging into a RV pedestal with low voltage, and it happens more often than you think! In summer for example, many RV parks are just not properly equipped to power a full load of RV’s all running multiple air conditioners. So, supply voltage drops which means your RV will try to pull more amperage out of the pedestal (to get the same power). This is really bad and can easily cause overloading and overheating of your wiring system. Power surges happen less often, but they do happen and when they do they can easily blow all the electronics in your coach. There’s many more examples, but either way bad power, low or high voltage can be a serious problem for your coach**.
**NOTE/ One of the BEST ways to avoid bad power damage is to use a quality Surge Protector which I will talk in detail about in my next post. So, look out for that….
How Can You Tell if Your ATS is Bad?
It’s not always easy to tell if your ATS is the culprit in an electrical problem (electrical issues are often called “gremlins” in an RV ‘coz they can be so darn tricky to track down), but CLEAR indications are burning smells from your ATS. charring or loose wires inside the ATS box and overheating (the box is hot). Also the ATS is one of the key culprits to check if you’re able to run your coach from generator, but not from shore power (and visa versa). It’s not always the root cause, but it’s one of the things to check.
How Did Ours Fail? A Combo Of Overheating & Bad Design
When we noticed the burning smell we quickly tracked it down to our ATS box which is right next to our main power reel in the back drivers side bin of the RV.
When we opened the box (AFTER turning off all power to the coach) we immediately saw charring on the inside the box as well as a bare wire which was lying on top of another wire. Yikes!! We check all our wire connections yearly, but clearly we had either missed this or it happened after our yearly check.
In addition to the loose wire we saw charring and some pitting which we think might have been related to some low power issues we ran into last summer. On a particularly hot day in Idaho last year we plugged into an RV park that had low power. Our 7-year old surge protector didn’t catch it (one of the many reasons we’re upgrading it), but we did and almost immediately too. Our front AC sounded funny as soon as it started and a quick check with the voltmeter at the park pedestal showed that one leg was only delivering 96V!! We only ran off the pedestal for a few minutes, but that little bit of time might well have overloaded our system enough to start the process that finally caused our ATS to completely fail 6 months later. Total speculation here, but it’s a definite possibility.
Another thing which likely contributed to our ATS failure was simply poor design. The IOTA ATS-50R that came with our Holiday Rambler is a flimsy plastic box with rather tightly-spaced connections inside. Once I started investigating it on RV forums I found out that MANY folks have had problems with that switch specifically, the most common failure being overheating & electrical fires (I can’t tell you how many pics I saw of boxes that were charred and burnt way worse than ours). Even more telling is that, unbeknownst to us, Monaco and Keystone both initiated recalls of these switches back in 2012!! So, in addition to lose wiring and (maybe) some low voltage issues, the IOTA switch that we had was basically just poor quality.
Choosing A Replacement -> The ESCO LYGHT LPT50BRD
Choosing a replacement for our RV ATS was pretty simple. There were just a few things we looked at:
- Power Specifications -> The ATS had to be able to handle the max power that we planned to put through it. In our case that meant it had to support 50Amp and be able to handle our 8kWH generator. Pretty much all 50Amp-rated ATS switches can do this (most can handle 12kWH generators, actually), but it’s always important to double-check before you buy.
- Construction -> No more flimsy plastic for us. We wanted metal box and metal supports….basta!
- Size -> We had very little space to work with in our reel bin, especially as we wanted to upgrade our surge protector and place it in the same bin too (more on this in my next post) so we needed our new box to be almost the same exact same size as the old IOTA switch. It was going to be tight.
- Cord Access –> Because of our space constraints & the way the old switch was wired in our bin, our new box needed to be able to take all our 3 cords (shore power input, generator input, output to coach) on the right-hand side. So we wanted a box that was flexible in how it could be wired.
- Noise -> This is kinda techie and not really critical because of where the box is located (we never hear it in the external bin), but we figured we might as well try to get one of the slightly fancier ATS boxes that have DC-coiled relays. These get rid of the “humming noise” you often hear with older ATS boxes.
There are LOTS of well-rated ATS switches out there including Parallax (these are REALLY nice boxes and were initially our first choice, but they were just way too big for our small bin space), Surge Guard (also quite nice, but wrong input cord orientation and way to big for us. They make integrated ATS/surge protection boxes too which are kinda nifty, but not what we wanted either), Progressive Dynamics (also nice, but also not the right size/orientation for our need) etc.
In the end we went with the LYGHT LPT50BRD made by Elkhart Supply Corporation (ESCO), bought thro’ Amazon for ~$180. It’s an all-metal construction, well-rated box which was an almost exact size replacement for the IOTA (lots of Monaco/HR coaches have used this exact switch as their replacement). Plus it had multiple knock-out inlet holes, could be installed pretty much any which way and fit the other requirements we were looking for.
The Replacement Installation
A WORD OF WARNING -> BE CAREFUL working around electricity. 120V can KILL, so don’t start poking around your ATS switch unless you have ALL power turned off (including the breaker to your generator), and definitely don’t do this yourself if you are not 100% comfortable with electrical work.
Although Paul is pretty comfortable working around electricity, we decided to be extra vigilant and brought in a local friend and RV tech-guru Mike to help us with the installation.
Apart from the constraints of working in a very tight space it was a fairly easy process. Mike did have to move around two big wires (we needed to flip the position of our house and generator wires) plus he needed to add an extra length of 50Amp cord (to link the ATS to our our new surge protector == details coming up in my next post), but other than that there were no big gotchas. The box fit (only just, but it fit!) and it was straight-forward to wire up.
When everything was finally in place it was just a question of plugging in the RV, testing the switching function (by starting our generator) and checking that everything powered in the coach the way we expected. Not much more to say about this except that Mike did a beautiful job.
NOTE/ Mike is a certified tech and does this kind of work part-time in the local Margate, FL area. If you’re interested in contacting him for your needs here are his details: Mike Chartier 860-884-2095
Final Words & Thoughts
Obviously we’re VERY happy that we caught this issue before it became a real fire. Checking the main wiring connections in your RV is something everyone should do on a regular basis, but even then you might miss something like this. So, be aware of odd smells and heat coming from places they shouldn’t (we carry a little Digital Laser IR Thermometer Gun for just this purpose).
Also if you’re ever in a “bad power” situation like we were in Idaho last year, make the extra effort and look at your panels and inside your ATS switch to see if there’s any damage. We caught the low power issue really fast and didn’t immediately smell or notice anything when it happened so we figured we were fine, but maybe we would have noticed some damage if we’d opened the box and checked inside? Lastly, if you have an old IOTA switch in your coach I definitely suggest replacing it ASAP. My research on the IOTA ATS reveals many people have had similar issues to us and you’d be better off simply replacing the box altogether.
All in all we’re very happy with our replacement choice and installation. Our new ESCO ATS feels sturdy, emits absolutely ZERO humming noise and is working flawlessly. Fire avoided, RV electrical back on track….phew!
Coming Next -> All about Surge Protectors & our new, snazzy upgrade