Scamp 120V follies (tandem breakers)

[Timber Wolf]

Even though I know better than to try and fix stuff that ain't broke, I could not resist the urge to do so last week. In the end it worked out but not before some head scratching on my part.

This sorry tale begins a year or more ago when I added another 120V circuit to the Scamp. It fed a couple of new interior receptacles and one outside under a weatherproof cover. Since I had 12 gauge wire on hand that is what I used although the rest of the Scamp is wired with 14.

At the time I added the new wire with another one on one side of the existing sole tandem breaker. Even though the breaker box has space for two (full size) breakers, my 1988 Scamp only had one, tandem, breaker. A tandem breaker is a means to allow two separate circuits to occupy the space ordinarily occupied by just one in a breaker box.

As the other side of the 15-15 tandem already had two wires under it I decided to get another tandem breaker and separate the wires each to their own breaker. Again, fixing something not broke, but an "improvement" nonetheless. I dropped by Home Depot and found the correct tandem breaker on the shelf. I chose a 15-20 as my new circuit used 12 gauge wire and was good for 20 amps. Again, not really necessary, but why not.

The mayhem ensued when I put the new breaker in, separated the circuits, and the two "new" circuits were now dead. In my Scamp the breaker box is under the sink, in the back of the cabinet, over the wheelwell. Kinda tight back their it is. Wide as I am, I really can only get one arm/hand in to work on stuff. I pulled the breaker, hooked the wires back up the old way, and everything worked. Hmmm, the new breaker could not be bad could it?

Anyway, as usually happens when I take a break and just look at an issue calmly, I saw the problem. The two tabs that energize the breakers are not connected, each has its' own feed lug. At first I did not understand this, but then realized why. The box is intended to be able to hold one 220V breaker, which needs two separate legs. I simply added a 10 gauge jumper wire from the other side over the top, redid the wires and new breakers, and all is now well.

It is pretty much over-kill but should allow easier troubleshooting in the future. Although hopefully I won't have any more trouble!

[Captleemo]

What was your reasoning for not using two single pole breakers? A tandem (double pole) breaker is not designed for two wires on one circuit but for 220 volts as each pole lands on a separate bus each being 120 volts but a pole to pole reading with a volt meter would be 220 volts. And its not good practice to put two circuits on a single breaker. People do it but its not a good idea.

[redbarron55]

Originally Posted by Captleemo

What was your reasoning for not using two single pole breakers? A tandem (double pole) breaker is not designed for two wires on one circuit but for 220 volts as each pole lands on a separate bus each being 120 volts but a pole to pole reading with a volt meter would be 220 volts. And its not good practice to put two circuits on a single breaker. People do it but its not a good idea.

I would think that these are approved by rating agencies and als long as you don't exceed the current limits the should be OK.
That being said a lot of the RV breaker panels have pretty cheesie busbars for the line side.
I would say if you want to break the lines into more separate feeds the current loads would be lower than fewer feeds with high loads.
Whatever you do do not exceed ratings.
By the way I have seen a lot of RV breaker bussbars in converters that were riveted aluminum and I would expect them to be as problematic as I have seen.

[Timber Wolf]

Originally Posted by Captleemo

What was your reasoning for not using two single pole breakers? A tandem (double pole) breaker is not designed for two wires on one circuit but for 220 volts as each pole lands on a separate bus each being 120 volts but a pole to pole reading with a volt meter would be 220 volts. And its not good practice to put two circuits on a single breaker. People do it but its not a good idea.

A tandem breaker IS two single pole breakers, and is NOT a double pole. This is proven since a tandem only locks on ONE leg in the panel. And in reference to your last two sentences, that was the whole point of this exercise to separate the circuits.

[TheWanderers]

I have rewired the incoming let of the shore power connection in our 1991 Scamp and have found exactly what you describe, including the jumper from side-to-side. And, I agree, there ain't near enough room for two arms under there to work.

[Joe Romas]

Slightly related. A recent thread on the casita forum shows a charred mess cause by loose screws inside a converter. Several have found the screws inside their converters loose.
Checking the screws inside our converters should be a yearly thing.
http://www.casitaforum.com/invboard/...-at-connector/

Joe

[redbarron55]

The old converter I had and one I got for free from a salvaged popup had bad 120 volt busses where the circuit breakers connect. In these cases the buss was aluminum and it was more or less (mostly less) pop riveted in place and had a bad connection which heated up and melted the plastic mounting.
Bad design.
In the PD4045 the incoming breaker connects to the buss and the power is fed from there and it is much better and is tinned copper and not aluminum.