Converting from 30 amps to 50 amps

In the world of RV park living there are three standard options for “shore power”, 20 amps, 30 amps, and 50 amps.  Most RV parks provide 30 amps at each site, but there is wide variety of possibilities out there. While some will offer multiple hookups with a combination of the three  power options at every site, others may have only one kind of hookup across the rv park or have separate sites dedicated to specific amperage loads.  With so many options there’s a good chance few will ever need to convert their setup. However, after roughly nine months of living with 30 amp power we decided to convert our school bus from 30 amps to 50 amps. Maybe our experience will help someone out there with this same decision.

When we first began building our skoolie we had to make  the amperage choice and after some back and forth we chose to go with 30 amps.  Given that it sits in the middle of the 20-50 amp spectrum, we thought 30 amps would allow better flexibility is we needed to use an adapter to switch from 30 amps to either 20 or 50amps.  For this simple reason opting for 30 amps could be deemed the “sensible” choice for any skoolie builder.

If we traveled somewhere, where we would only have a 20 amp outlet at our disposal we could always use our Camco 55223 15M/30F AMP PowerGrip Adapter which is exactly what we do when we park at a friend’s or family member’s house. A 15 amp home outlet, the kind to be found in just about any bedroom of a house is good enough to deliver electrical power up to the same extent that might be used in a typical household bedroom. That means that everything from the coffee maker to the computer along with the interior lights can be run from a simple 15 or 20 amp outlet. But it also means that in order to avoid blowing a fuse, or tripping a breaker, one has to consider the load before running the AC, the refrigerator, or anything in combination with either of those. At 15-20 amps, one can live, but few will want to live like that for long.

If by contrast we traveled to a park that only had 50 amp power hookups, then we could just as well use another adapter like the Camco 55175 PowerGrip Dogbone Electrical Adapter with Handle, 18-Inch, yellow. These adapters, commonly known as dogbones, are typical fare at any RV park. By hooking up our 30 amp system to a 50 amp outlet we had been able to use all of our appliances without worrying about pulling too many amps that the breaker might trip.

Ultimately, though, our decision to opt for 30 amps came down to the most pressing of considerations; money and our lack of it.  When we hit the road in August of 2016, our skoolie was partly unfinished and we were simply broke. Knowing that we still needed to add various “necessary” features like water tanks, a proper AC unit, and a water heater, we knew we needed to conserve our meager funds for another day and as it turned out going with the 30 amp option was our best practical and economical option.

As we found out, the 30 amp inlet and outlets are a bit less expensive ( by only a couple bucks) than the 50 amp variety, the cost of the necessary sjoow cable to make a power cable is another story all together.   At the time of the build we needed a cable run of 50 ft to reach the nearest outlet to our bus which was only a 15 amp household outlet.  Commercially available 30 amp power cables are rarely that long with most only reaching 10-25 ft.  Prices for these cables tends to vary greatly, but at the time it became clear that wiring our own cable would be less expensive.  We simply needed a 50ft of 8/3 awg gague cable in the sjoow specification. ( SJOOW, simply means that it is rated for Junior Service, from one electrical box to another, that it’s made with Oil resistant insulation and covered by an Oil resistant outer jacket, and that it is Weather resistant.) However, for 50 amps we would need 50ft of 6/4 awg cable. A much thicker and 30% more expensive cable.

We knew that eventually we would have to go up to 50 amps simply because our budget was so tight that we realized we would need to use household appliances rather than the typical appliances made for RVs.  Though rv appliances tend to run on a lower wattage, they are often 3x the price of household appliances.  Therefore, at least until we setup our solar system, we would have to trade-off between our immediate budgetary constraints and our future electrical costs.

With that future upgrade in mind we installed a main lug ( a secondary or extension electrical panel box) with a 125 amp capacity as our primary electrical breaker panel (specifically this one: GE Energy Industrial Solutions TLM612FCUDP Main Lug Convertible Load Center, 125-Amp) so that we would have enough room to expand in the future without worry of over powering the box or having to rewire the entire bus.

So why did we decide that it was time to convert from 30 amps to 50 amps?

It was a cold winter.  Our attempt to properly insulate the bus (during summer in Florida) proved inadequate for what would otherwise be considered the mild Texas winter of 2016/2017.  Not only did we have some pipes freeze but we found that we needed extra portable heaters to make it through 30-40 degree days.  The space heaters would now and then cycle power in unison and trip our breakers, 30 amps was just not enough. To make matters worse, when the pipes were not frozen, the water was still painfully cold which made simple things like showering and washing dishes feel like brief plunges into arctic waters.  So we decided that not only did we need enough power to handle the use of portable heaters, but also enough to handle the added power needs of a water heater.

Thankfully, our decision to install an over-capacity electrical panel paid off.  We could wire any of these appliances into isolated breakers and did not need to rewire the inside of the bus to accommodate our winter appliances. Still, everything between the electrical panel and the hookup at the RV park would need to be replaced; the power cable, the power inlet, and the wiring of the inlet into the electrical panel.

The water heater we chose was the Rheem RTE 9 Electric Tankless Water Heater, 3 GPM by Rheem which happens to draw a maximum of 38 amps at peak. This is a lot, but as it is a tank-less water heater it only powers on when the hot water is turned on. The effect is that at its highest/hottest setting it pulls a sharp spike on the power load, which is why the instructions call specifically for an isolated 40 amp breaker in the electrical panel. Having the extra capacity in the electrical panel made this an easy upgrade; we just wired the water heater to a 40 amp breaker and popped the breaker in.  For added mental and emotional certainty, we placed the breaker so that it straddles the left and right phases of the panel.

To complete the conversion, we needed to change the inlet to a 50 amp inlet and acquire a new power cable. At this point we decided to purchase an actual RV/boat power inlet with a cover and twist-lock feature. We chose this one: 50 amp 125v/250 Power Cord Twist Electrical Lock White Inlet Boat RV Marine. Then, since we would only use such a cable at RV parks we could then use a power cable that was no more than 25ft, and one that included a twist lock to go with the new inlet. (The one we bought is no longer available but this one is comparable: 25 foot, 50 amp RV power supply cable cord, detachable, removable).

To connect the new 50 amp power inlet to the electrical panel, we went to Home Depot and purchased four, 1.5 ft long, 6 awg stranded cables in red, black, white, and green colors to match the standard wires of an SJOOW cable and the color coded sockets on the inlet itself.   Then, we connected the colored wires according to standard electrical practice with the red and black as live inputs, with one into each of the phases of the panel, with the white wire connected to the neutral bar, and the green connected to the ground bar.  And we’re done.

So what do we do if we find ourselves at an RV park that doesn’t have 50 amp hookup, or one that charges extra for 50 amps?

Then we use the adapters mentioned earlier in the article and just manage our power consumption to match the available hookups once again. No big deal.  At least we are now prepared for next winter and what ever else may come (like a new Air Conditioner).

Final Recommendation for Skoolie Enthusiasts:

Since one cannot predict which power hookups will be available at each rv park, or which specific ones will be available when pulling into an rv park in the middle of the night without reservations, having the right adapters/dogbones will always pay off no matter which power capacity one chooses.  Given our needs, as full-timers living and working out of our bus, 50 amps just makes perfect sense.  And unlike RV’ers with their pre-built, and pre-wired setups, skoolie enthusiasts have to make a choice and we see no reason to be restricted to 30 amps.

One Comment

  1. Thanks A Lot For Posting, Your Post Is Very Useful

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