Can I replace 12v light switches with 110v house switches?

2oldman wrote:

DrewE wrote:

2oldman wrote:

Bobbo wrote:
The DC circuits arc MUCH more than AC circuits do when disconnecting (turning off the switch).

For lighting?

Yes, for lighting.

LED lighting? They draw almost nothing.

All we can give you is the principles involved. You will have to work out the implementation yourself.

Principle - DC arcs much more than AC during disconnect.

Implementation - LED lights yes/no?

DrewE wrote:

2oldman wrote:

Bobbo wrote:
The DC circuits arc MUCH more than AC circuits do when disconnecting (turning off the switch).

For lighting?

Yes, for lighting.

LED lighting? They draw almost nothing.

2oldman wrote:

Bobbo wrote:
The DC circuits arc MUCH more than AC circuits do when disconnecting (turning off the switch).

For lighting?

Yes, for lighting. With AC power, the arc naturally self-extinguishes during the zero crossing that happens 120 times a second; that's missing with DC.

An inductive load is worse in either case, of course.

Low current DC switching should not be an issue with most residential home type switches.

I have done that for years with no issues.

My first TT I retrofitted the trailer with wall mounted Decora switches, making sure that no more than two 20W incandescent lights (3A at 12V)were on each switch.

My current TT, I did the same although now, I have switched all the incandescent bulbs to Lower power LEDs..

DC arcing typically is not a problem at LOW CURRENT, higher current switching can present a problem with the arc not extinguishing due to the contacts not having enough distance.

I suspect as long as the current is below 5A at 12V there should not be an issue..

On edit..

For kicks and grins I looked around my junk pile and pulled out a RV fixture that I replaced when remodeling my TTs..

Yeah, this is a single 20W 12V (1.3A )bulb incandescent fixture and the switch rating is 1A at 125 DC/ 4A 125V AC/ 2A 250V AC!!!

You read that right ONE AMP AT 12V DC to handle a bulb drawing 1.3A at 12V!!!



Yeah, I suspect that if that cheesy switch which has been used in hundreds of thousands of RVs hasn't burned on down then I would think that a residential home switch which is rated 15A at 125V AC should be able to handle a couple of Amps at 12V.

tommymsw wrote:
Something like THIS would be PERFECT as they are still small, but look nice. I can also find them in 3-way. I think I should start a business making 12v switches :)
https://www.amazon.com/dp/B072N6DRQP/_encoding=UTF8?coliid=IKVG83FU7MHES&colid=18G4KIFGQMKTV&psc=0

So if you like 'em, buy 'em ... what's the issue? :h While the conversation about DC switching in submarines may be interesting that hardly applies here where I'd find it difficult to imagine you'd be switching any DC loads at all that are significant enough to make any difference at all by using an AC switch such as you've illustrated. Actually, now that I think about it my own Coachmen has several of these paddle switches that are used to turn interior lights on/off, heck even the exterior entry door light.

Bobbo wrote:
The DC circuits arc MUCH more than AC circuits do when disconnecting (turning off the switch).

For lighting?

You can buy a switch like that at Home Depot. When you say size is no issue are you considering the mounting depth as well as the surface area? Most exterior walls are not deep enough for a standard electrical box so they have spacer rings to make up the depth, see example below:



Since most RV lighting circuits are fused at <10A, 12vDC does not present the same shock/fire hazard as household 120v, so RV light switches don't have to be mounted in the same insulating boxes as household switches.

You could always do something like this, same size as a residential switch but surface mounted. Click pic for link.

Size is not a problem. I have plenty of room for the larger switches. But this is turning out to be REALLY difficult. Now only can I not find any "good looking" switches, but they are REALLY expensive (compared to AC) and I have been unable to find any "3-way" switches (that is what I have now).

Something like THIS would be PERFECT as they are still small, but look nice. I can also find them in 3-way. I think I should start a business making 12v switches :)
https://www.amazon.com/dp/B072N6DRQP/_encoding=UTF8?coliid=IKVG83FU7MHES&colid=18G4KIFGQMKTV&psc=0

I would suggest that those who have never seen a switch rated for both AC and DC look up JR Products on line and read the specs for the switches they offer for RV use. You might try looking up Sigma also.

Twenty years ago there were hundreds of thousands of relays used for switching power for traffic signal lights. The better relays used a silver alloy for the contacts and they were replaced by solid state relay because they were switching on and off under a load and causing metal transfer between the contacts.

Today's solid state switches use what is called a soft start, no current flow when the gate is turned on and current rises at a very rapid rate. A zero start is better for not only the relay contacts but it was easier on the filaments of incandescent lamps and they lasted longer. Electro-mechanical relays cannot do this with any consistency and neither can manual switches.

Every one of the members of this forum who is qualified on Submarines can attest to how the power to propulsion motors are always started at "0" volts and "0" amps. The amperage can rise very fast after the contacts are made but making or breaking at say 1500 amps can be catastrophic. Submarines to not take well to catastrophic events.

I would guess that a residential on/off wall switch rated for 15 amps, would be capable of carrying about 5 amps at 12 VDC.

Using switches not rated for DC on DC circuits can cause significant problems. The DC circuits arc MUCH more than AC circuits do when disconnecting (turning off the switch). You are likely to get a lot of pitting of contacts on the AC rated switches and have gremlin type problems down the road. Get either a DC rated switch, or an AC/DC rated switch.