Using Circuit Breaker to turn Suburban Water Heater on Electric

[johnbryanpeters]

Bottom line:

The circuit breakers provided in WFCO power centers are SWD rated and it's perfectly OK to turn the hot water heater on and off using the breaker.

Now, if they'd only mount the power center at eye level so as not to require crawling on the floor while fumbling for the proper breaker...

[A32Deuce]

I think the switch outside on the Suburban is a great idea. After all set up, on the way in I hit the switch on. Day of teardown first thing is turn the switch off. Don't burn out the element by accident that way. I guess some don't like to be inconvenienced by having to open that little lock and pushing a button. Just my thoughts!

[5picker]

Originally Posted by Major Oz

No problem, as an ex-engineer said above.


The idiots in FR design located the elect/gas WH switch on the OUTSIDE in the water heater bay..........so we always use the circuit breaker.


Obviously, the folks who design/build these things don't ever use one.

I'm guessing you don't quite understand some things...

FR doesn't 'build or design' the water heater. They simply buy them (from several different manufacturing companies) and install them.

There ARE some models of FR R/Vs that HAVE two switches. (one inside and one outside) If you purchased a R/V that didn't have this option, that simply isn't FR's fault.

[Cowracer]

Originally Posted by 5picker

I'm guessing you don't quite understand some things...

FR doesn't 'build or design' the water heater. They simply buy them (from several different manufacturing companies) and install them.

There ARE some models of FR R/Vs that HAVE two switches. (one inside and one outside) If you purchased a R/V that didn't have this option, that simply isn't FR's fault.

Whaaaaa? Forest River should be able to read my mind and provide me exactly what I want, even before I know I want it! Talk about a cheapskate company with no desire to take care of its customer!!!

[/sarcasm]

[Mach428]

I installed a switch below the sink to replace the one outside. The pilot light only glows as a reminder that the heater is on.

[Larry-NC]

Originally Posted by A32Deuce

I think the switch outside on the Suburban is a great idea. After all set up, on the way in I hit the switch on. Day of teardown first thing is turn the switch off. Don't burn out the element by accident that way. I guess some don't like to be inconvenienced by having to open that little lock and pushing a button. Just my thoughts!

I can't see the switch on mine. The cabin is in the way. To drain the heater I lean on the cabin and reach in, mostly one-handed.

I put a switch with pilot light inside, under the range.

[cfo111]

I think every one is over thinking it's a camper and what he is asking not like turning you lights on Evey day 365 time a year . maybe a few times a year.

[grumpyoldman]

I was going to add a switch in a more convenient location when I came upon a remote control outlet. It plugs into the water heater outlet and the water heater plugs into it. It has a key fob type remote control. It makes it easier for the DW when she goes to our seasonal site by herself. I added a pilot light to the inside switch panel to indicate when the WH is powered on.
I also added one for the converter so I can turn it off when I want to. The converter CB also shuts off outlets on one side of the camper so I couldn't use it to shut off the converter.
I bought a package of 3 of these remote outlets so I used the third one for the power strip that feeds the TV, DVD player, ROKU player, wireless printer and a cable modem. It makes it very simple to shut off all the electronics with a push of a button on the remote. Same thing with the WH.
Did I mention I like gadgets

[Cowracer]

Originally Posted by cfo111

I think every one is over thinking it's a camper and what he is asking not like turning you lights on Evey day 365 time a year . maybe a few times a year.

Nobody is overthinking anything.

The OP wanted some information. Information was provided.

Tim

[joshuajim]

Let me see if I understand this. Breaker contacts arc when opened or closed thereby damaging the breaker with relatively few cycles, but the wall switch in my house which also has contacts is cycled many times a day, 365 days a year and possibly for 30 or more years. I guess $5 wall switch must be manufactured to a much higher quality than the breaker.

[Cowracer]

Originally Posted by joshuajim

Let me see if I understand this. Breaker contacts arc when opened or closed thereby damaging the breaker with relatively few cycles, but the wall switch in my house which also has contacts is cycled many times a day, 365 days a year and possibly for 30 or more years. I guess $5 wall switch must be manufactured to a much higher quality than the breaker.

No... just a different function.

Tim

[bob213]

Originally Posted by joshuajim

Let me see if I understand this. Breaker contacts arc when opened or closed thereby damaging the breaker with relatively few cycles, but the wall switch in my house which also has contacts is cycled many times a day, 365 days a year and possibly for 30 or more years. I guess $5 wall switch must be manufactured to a much higher quality than the breaker.

I'm not an electrician so I could be completely wrong but just thinking about it I would have to think that there are very few times when a single light switch would be carrying the entire load of the branch circuit so there would likely be less arch at the light switch than at the cb?

[NorSnrub]

Originally Posted by joshuajim

Let me see if I understand this. Breaker contacts arc when opened or closed thereby damaging the breaker with relatively few cycles, but the wall switch in my house which also has contacts is cycled many times a day, 365 days a year and possibly for 30 or more years. I guess $5 wall switch must be manufactured to a much higher quality than the breaker.

Attach a small capacitor across the circuit breaker to prevent arcing.

[johnbryanpeters]

Originally Posted by NorSnrub

Attach a small capacitor across the circuit breaker to prevent arcing.

Do that on an AC circuit and the results might be very interesting, like melted capacitor followed by arcing where it used to be...

If you don't understand electricity don't screw around with it.

Signed,

Retired electrical engineer who used to do a lot of power systems work

[Cowracer]

Originally Posted by bob213

I'm not an electrician so I could be completely wrong but just thinking about it I would have to think that there are very few times when a single light switch would be carrying the entire load of the branch circuit so there would likely be less arch at the light switch than at the cb?

Inside every engineer is a frustrated teacher just dying to get out. So, here goes.... (Feel free to skip over this if this little derail doesn't interest you)

Every energized opening connection will arc load, or no load. An arc is formed when the air ionizes. Normally, air is a fairly good insulator. But when it ionizes, it turns somewhat conductive. The arc starts the instant the contacts open, ionizing the air, and keeping the current flowing, even as the contacts keep moving apart. This generates enormous heat, and will melt part of the contact metal, where magnetodynamic forces will fling the microscopic beads molten contact metal all over the place. Done enough times, it can ruin the contacts.

To what degree it arcs depends on voltage, current and of course, load, among other factors. Even closing a contact will arc a bit due to "bounce". The closing contact will literally bounce and open briefly. When I program mechanical switches in a control system, I have to 'de-bounce' them in the code so I only react to one closure.

Many methods have been tried to deal with the arc. In low power applications like 110vac, you just design the contacts so that the arc is either not that detrimental to the lifespan (i.e. thicker contact material), or designing the contractors with a sacrificial part that is concentrates the arc to a small part of the contact where its effect is negligible.

With higher power/higher voltage circuits, the most common is just putting whats called 'arc-quench chutes' in place. Those are just a series of non-conductive baffles designed to turn a big arc into a lot of little, less long-lived arcs. High enough voltages can make an arc that can sustain itself far over the distance of the fully open contacts. You see these a lot under 600 volt circuits.

In high voltage gear (up to about 4160 Volts), they used to have things such as an air-blast, to physically "blow-out" the arc or contacts submerged in mineral oil to prevent arc. Neither one is ideal. The most popular way now is vacuum contactors, where the actual contact is in a container evacuated of all air (no air = no ionizing = no arc). These units are WAY smaller than any other kind, but also way more expensive and fragile to mechanical shock.

When you get up in the really high voltages, like in power transmission lines, you pretty much give up on containing the arc, and just give it somewhere to go.

Here is a video of a 69,000 volt switch gear opening. Notice the 'whiskers' on the tops of the moving and stationary contacts. Those are sacrificial, and give the arc something to burn up instead of the contacts until it opens far enough for the wind to blow it out.

https://www.youtube.com/watch?v=86xWJ8BAwxE

All the way up to a big boy 138,000 volt circuit opening, where it looks like something really wrong has happened. The tips of the moving rods are the sacrificial parts. Pretty sure they don't open those every day.

https://www.youtube.com/watch?v=3WU6xtPWyrc

Those two videos are taken with all the loads off the system. That's just the voltage doing the arc. There is no current. Now THIS is a 500,000 volt switch under load opening up.

https://www.youtube.com/watch?v=vqgNrj6oEdc

Never got to see something like that live, yet. Kinda want to. Equally kinda don't want to...

If the system, from a 110 light switch to a 500KV transmission line switch, is designed correctly, the arc is non-destructive. Of course, if not designed correctly, or if something breaks, the arc can be like a bomb going off.

This is my personal video. This was taken at a place I worked. Had a failure in our power distribution system casing the feeder switches to arc. Notice the wind blowing the smoke right-to-left? That smoke contains ionized air, and you see what happens when it reached the transformers, about 15 feet to the left of the initial arcs. (skip to 0:16 for the action shot)

https://www.youtube.com/watch?v=SVOQZnQOYn4?t=16

One last little tidbit... Everyone asks why the breakers didn't blow. It's because a 'thru-air' fault like this actually don't conduct very much current. The ionized air is conductive, but not greatly so. The resistance it provides usually keeps the current below the trip point of the breakers. What finally ended it was our local utility's equipment noticed a mondo phase imbalance, and shut down as a precaution.

And that concludes today's episode of "Fun With Electricity!"

Tim

[Larry-NC]

Originally Posted by Cowracer

Inside every engineer is a frustrated teacher just dying to get out. So, here goes.... (Feel free to skip over this if this little derail doesn't interest you)

Great videos and discussion. Reminds me a little of when the 7200-440 volt 3-phase transformer that shares our pole blew up. Four or five days earlier the 440 side had wet branches blowing against the bare wires strung through the ravine. The loading caused an internal short. The internal heating caused a runaway, and about 1 AM the top of the transformer blew off, throwing white-hot metal into the sky like a Roman candle. The oil was burning with a smoky orange flame.

My late wife suggested I call 911 and I did so. Then she suggested I call the power company, too. I told her we couldn't--that the phone lines had burned through already. She had to pick up the phone to see for herself.

About that time, the bottom of the transformer can burned through. The rest of the flaming oil ran down the pole, puddled at the bottom, and then began burning back up the pole from the bottom.

First to arrive was the cable guy. He had been working in the area and when he saw the sudden outage, he just kept coming upstream until he found the cause. Next was the fire department. They weren't going to touch it until the power company assured them it was safe. When the power company got there, they got the go-ahead and extinguished the burned-half-through pole.

First to arrive the next morning were environmentalists from the power company, to make sure there were no PCBs in the oil. I don't think the pole got swapped until the next day. Very busy pole. 7200 VAC in T configuration, with two transformers, 440 VAC, 3 phase to the 15 HP motor at the neighborhood swim club and 220 VAC, split-phase to five houses, plus telco and CATV. Once the new pole was set alongside the old one and the transformers were moved, the telco got started on splicing their cable which had 480 (!) pairs to splice. That took two more days. Then the cable guy got his turn.

A couple of other thoughts
Sometimes semiconductor switching is used. They solve the problem by sensing the zero-crossing point of the voltage and opening/closing at that point.

In the videos, did you notice that the arc rises? You would expect that the arc would take the shortest path between the two electrodes, but it doesn't sometimes rising several feet. This actually occurs because of convection. The locally heated air rises and "blows" the arc upward.

I'm in the habit of scavenging neon sign transformers 15,000 VAC, maybe 20-60 mA. and making Jacob's Ladders from them. If you put a clear enclosure about the electrodes, open at the top, with vent holes at the bottom, you can cause the arc to rise, even though the electrodes are diverging (longer path). You can prove that convection is at work by plugging the vents or blowing down from the top. In fact, when it is first started, the arc stays at the bottom (shortest path) until enough air is heated to cause convection. I will probably put one out for Halloween again.

[NorSnrub]

Originally Posted by johnbryanpeters

Do that on an AC circuit and the results might be very interesting, like melted capacitor followed by arcing where it used to be...

If you don't understand electricity don't screw around with it.

Signed,

Retired electrical engineer who used to do a lot of power systems work

.01Pf 1000 v not an electrolitic.
I was in electronics for years. They put them on the old points in cars to protect them from arcing.

[johnbryanpeters]

Originally Posted by NorSnrub

.01Pf 1000 v not an electrolitic.
I was in electronics for years. They put them on the old points in cars to protect them from arcing.

Voltage to points in cars is DC.

[Larry-NC]

Originally Posted by NorSnrub

.01Pf 1000 v not an electrolitic.
I was in electronics for years. They put them on the old points in cars to protect them from arcing.

0.01pF is not enough to prevent arcing. Since you mention automotive breaker points, stop and think about their physical size. They must have been up in the microfarads.

0.01pF is used to shunt radio frequency--used across the power line of electronics so internal RF doesn't radiate from the attached power cord. Won't do anything useful at 60Hz.

Any capacitor big enough to quench a 60 Hz arc would conduct some current at 60 Hz.

[Ultraclassic]

Originally Posted by cfo111

No down side worked for Westinghouse and for years test up to 2,000 on and off no fails. Many large building turn off and on power daily every day with breakers.

Yes use the breaker as a switch, like posted here my first Auto shop that's all we had for 15 years, every morning and evening we turned off the lights with breakers, my electrician didn't like it though
😁