Suggestions on controlling line voltage for switching on/off lights and neon

I was browsing Amazon.com and found these pre-made relay boards…

SainSmart 2-Channel Relay Module for Arduino/Microcontrollers
4-channel version
8-channel version

The relays are made for microcontrollers like the Arduino, and can switch 250V AC 10A.

I have a number of neon lights/signs, and regular bulb outlets that I would like to have the Arduino control based on the amount of ambient light outside. Pictures of the lights are included below.

My father knows more about line voltage than me, and he said that the main line power is more likely than not 15A-20A. He also said that if I was to send 15-20 to those relays, that since they are 10A relays they should only output 10A. I figured I’d get a second opinion on this. He also said, however, that the neon may need more than 10A.

Before checking with a certified electrician to get an idea of the specific power needed for these neon signs, i figured id ask here to see if anyone has worked with neon in the past or present and get their opinions.

Basically, I want the arduino to switch the signs and lights on once the ambient light level drops below a specific amount, turn some of them off at a specific time during the night (would require either a real-time clock or i could use my ethernet shield to poll a PHP script), and then all of them off once the light is above a specific level. I don’t have the office open 24/7, so we don’t always need the main sign turned on.

See attachments below for images of neon.

We have 2 of the neon “Office” signs depicted in Photo 1, one on each side of the office.

The main Motel sign in Photo 2 is made of a number of parts.

  1. The motel sign itself
  2. the neon that says “Budget Inn” (previous business name). We covered it with semi-translucent plexiglass to diffuse the light a bit. We plan to paint a WiFi logo on the plexiglass to help mask the previous business name. Just like the office neon, there are 2 neon "Budget Inn"s, one on each side of the sign.
  3. The “No Vacancy” neon (again, 2 of these, one on each side). Something went bad with the power supply in the sign box itself and we cannot get it working, but we’re still looking into it. The “NO” portion is turned on and off via a switch on the sign itself (a bit inconvenient). As of right now, do not take the No Vacancy part into consideration.

Photo 3 is just two CFL lights over top of the car port for guests when they arrive. Dead center is a wireless X10 motion detector that switches a lamp in the office to turn on, as well as a light in the managers quarters (my home) attached to the office, alerting me to a car pulling up. This helps give me a minute or so to be ready, as opposed to a door buzzer (which I also have just in case I am not near the light).

In the office I have switches to turn on/off the 2x Office Neon (one switch), the Budget Inn neon (one switch), the main sign (one switch), the office lights (one switch), the car port lights (one switch), an outlet outside of the office (one switch), and a few additional switches that appear to be legacy and no longer appear to work.

Basically, would these relay modules be able to handle dealing with the neon lights, or would I need something a little more beefy?

He also said that if I was to send 15-20 to those relays, that since they are 10A relays they should only output 10A.

He is wrong, what will happen is that it will go bang and you will get nothing out of it ever again.

Grumpy_Mike:

He also said that if I was to send 15-20 to those relays, that since they are 10A relays they should only output 10A.

He is wrong, what will happen is that it will go bang and you will get nothing out of it ever again.

K, so i will need something beefier than those relays, yet is still switchable via a microcontroller.

I know this is from the UK but this sort of thing is what you want:- http://www.virtualvillage.co.uk/40a-ssr-solid-state-relay-for-ac-devices-003602-009.html?utm_source=googlebase&utm_medium=shcomp&utm_campaign=google_shopping_feed

or this:- http://www.virtualvillage.co.uk/60a-ssr-solid-state-relay-003602-006.html?utm_source=googlebase&utm_medium=shcomp&utm_campaign=google_shopping_feed

I hate to say this but a much easier solution is to use some X-10 modules and a programmable controller. They aren't 100% reliable but I have been using them for my floodlights and for my Electric Thermal Storage Heaters (Creda units from the UK, Mike) for decades.

Don

I wonder if…

Is there confusion, perhaps, between the maximum safe current for the circuit the signs are on and the actual current flowing?

When a relay is rated “10A”, it doesn’t mean that 10A will flow, or that no more than 10A will flow, through it. It merely says that the relay should not be put into a circuit where the other things, the things that determine current, will cause a current of more than 10A. Until it “goes bang”, as Mike so poetically puts it, the relay (when “on”, i.e. contacts closed) won’t affect the current.

===
Other matters…

This is a commercial premise. If you do things to the electrics, you may void your fire and liability insurance.

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Do the signs you want to control connect to the voltage that runs them via cords with plugs, that plug into sockets? If so… good. If not, if they are “wired in”, like, say, the light bulb in the ceiling of a room, then making changes would come under the “doing things” mentioned in the previous point.

If they plug in, there are answers… see…

www.arunet.co.uk/tkboyd/ec/ec1mains1.htm

relay (when "on", i.e. contacts closed) won't affect the current.

This is a solid state relay, there are no contacts. The current is passing through a Triac, that Triac has a current limit, if it is 10A then that is the maximum current. In fact it may well go bang with less than 10A if there is not sufficient heat sink.

Get a sparky to do the cabling and installation of the relays, and give you a spot to hook into control signals - the proper way to do it! That just leaves you to turn on / off the relays and set the controller up. Magic.

Like others said, first figure out where you will switch this stuff, and how it is wired.

If it's mostly wall type switches, then the X10 solution may be good. There are X10 switches that replace wall switches and can be remotely controlled by a timer or by a computer. Or by Arduino, with the right interface. I HOPE to have an X-10 shield done in about a month...

Here's some general stuff about power and relays with Arduino: http://arduino-info.wikispaces.com/ArduinoPower

SSR's are what you want. If X10 works, it's a miracle.

If X10 works, it's a miracle.

It works just fine for me, I started out with the original BSR products in the mid 1970s and am still using the system although none of the original units are still in use. The hardware is somewhat susceptible to failure so I wouldn't use the system for anything involving life support but for motel lights it will be fine. None of my units have burst out in flame or exploded but occasionally one will just stop working. The units are inexpensive so it's no big deal to keep a few extra on hand.

Don

As a side note - we did some X10 interfacing in one of our microprocessor courses (in the early 1980's I think). There was a little known ultrasonic hand held controller that interfaced with one particular model BSR control box. We emulated that ultrasonic device with our Mini Micro Designer microprocessor systems. This used an 8080 processor and had a whopping 256 bytes (no prefix) of RAM for the program. You had to reenter the program using an octal keypad each time you turned the unit on.

11 years ago I invested about 500 dollars on home automation using x10. my experience was that it didn't always do what you asked it to and now, very little of it still works. where I used SSRs, still working.

macharborguy: In the office I have switches to turn on/off the 2x Office Neon (one switch), the Budget Inn neon (one switch), the main sign (one switch), the office lights (one switch), the car port lights (one switch), an outlet outside of the office (one switch), and a few additional switches that appear to be legacy and no longer appear to work.

Basically, would these relay modules be able to handle dealing with the neon lights, or would I need something a little more beefy?

My 1st question : How you want to control all the lamp/loads ? I mean ... do you want the Arduino work independently or connected to a computer ?

Basicaly, all "digital switching" use some kind of relay. You can controll your relays using MCU, MCU+PC, or just simply PC Paralel Port (If you still have one). Since RELAY have a potential on doing some harm thing to MCU/PC ... peoples put some protection betwen them, the simplest thing is using darlington array ULN2803 ... or better with Opto Coupler.

First step, you need to know the max load that will handled by each relay, i.e : - the switch that on/off 2 lamp at the carport : What is the wattage number of each lamp ? what is your voltage ? If each is lamp is 100 watt, and your voltage is 110 .. then you will need a relay that capable to handle at least 3 Amp at 110 ... most of them capable up to 5 Amp

anyway ... Do you familiar with soldering and basic fabrication of box ? If not ... I thing you better consider http://www.sparkfun.com/products/9526

sincerely -bino-

thanks for all the helpful information.

All of the lights in question (both CFL and Neon) are switched currently from a set of wall switches (standard wall light switches). There are a total of 9 switches, but not all of them appear to do anything. I believe a total of 6 of them actually have any use (main sign, red neon on main sigh, "office" neon, car port lights, in-door office lights and outdoor power outlet).

The car port CFL bulbs are 25watt, but are equivalent to 100 watt incandescent bulbs. I believe some of the X10 equipment, or at least the wireless X10 stuff I currently have (albeit from 2004), are not compatible with CFL bulbs. As I said previously, i am unsure of the power being drawn by the neon and main motel sign.

All of the lights and signage are hard-wired in, as far as I can tell. The building is quite old, 50+ years I believe, so the electrical wiring is not very modern, and I believe it prevents me from using any "over the electrical wire" home-automation.

It would be nice if these servo switches were still available, but they do not appear to be, nor do I have access to a laser cutter. These would be perfect for my need.

The building is quite old, 50+ years I believe, so the electrical wiring is not very modern, and I believe it prevents me from using any “over the electrical wire” home-automation.

Two points

  1. 50 years is not old for a building
  2. There is nothing in 50 year old mains wiring that would stop any “over the electrical wire” home-automation

Back to the question of the relay cards.
Find out the wattage of each light.
Divide wattage by voltage.
There you have the current needed.
If the neon light requires 2000 watts, and your voltage is 240 Volts, then the amperage is between 8A and 9A.
2000 watts is a LOT of power, btw.

Now, if the relays do X amps, and you need more than X amps of current to support the wattage, then you may be able to wire the relays in parallel. Two 10 A relays can theoretically support one 20 A load. There’s a question of what happens if one relay takes slightly longer than the other to turn on, but “in most cases” that is “safe.”
Or you can buy devices that are made to take the current the way it is. If you get a SSR, remember that they typically dissipate some power themselves, and will need proper heatsinking.

macharborguy

What actualy is your goal ?

Do you want to controll the lamps from your PC ?

Sincerely -bino-

Two 10 A relays can theoretically support one 20 A load.

This is only true in the unusual case where the relays are always switched on BEFORE the load is applied, and the load goes away before the relays turn off.

Switching is the problem, and the make and break are not precisely the same on every relay.

Some relays have multiple contact surfaces on the relay contact itself, but this is only for reliability for low/signal switching. Relays, (or Contactors as the big brothers are called) have one big contact per pole.

If you really need more than 10 amps like the typical low-cost provide, use that relay to run a larger relay or contactor.

I have a 12V DC lighting system in my home, and it may carry 20+ amps. I have a large contactor rated at 50 amps with a 120 VAC coil that the regular relay operates.

binooetomo: macharborguy

What actualy is your goal ?

Do you want to controll the lamps from your PC ?

Sincerely -bino-

I am looking to make an automated control system via an Arduino micro controller to switch the lights on and off depending on the amount of outdoor ambient light outside, and possibly timed with a real-time clock module (in the case of the Office neon signs). Its a very possible project to do, I'm just looking over all of my options.