Hello so I’m working on a project to run a special HVAC/filtration system in my barn
Here’s my question…
Since I’ll have 12 relays, with the farthest one being 100ft from the Arduino mega, should I/can I use a separate power supply JUST for the relay power, then send a signal wire from the digital pins to the relay. My concern is I won’t have enough power from the 5v pin and the distance it’ll have to go to be able to power all the relays.
The power wire I have ran for the relays that is supposed to power them from the 5v or power supply is 14 gauge
For more understanding of what I have wired in my barn is a main 20 amp 110v line that runs the length on my barn. There are drop downs from the line. At the end of the line is a box. These box’s will have an outlet & the relays for specific appliances. This is the power the relay will be tuning on and off. In the same conduit pipe that houses the main power going the length of the barn is a ground wire & 5v wire that will be T-off/spliced into for each relay. Then I have separate signal wires in the main line for each relay
This is my second post ever, I learned from my first one that the more detail the better. The only diagram I don’t have is the placement of the components in the barn which I can draw up if needed.
Warning! Do not EVER run signal wires parallel with AC power wires. The signal wires connecting to your Arduino will be great antenna wires to bring the AC noise right back to your Arduino.
Back to splicing, huh? You never learn, do you.
If you want to add wires to the conduit, add a ‘hot’ wire for every outlet, mounting the relays near the breaker panel, outside the dirty area.
My smart home system has over 100 relays, some solid state others standard relays, all are 24V DC. They are driven from a 'driver panel' that uses ULN2803 drivers to power the remote relays. The system is wired with mainly 22 AWG multi conductor cable with some CAT cable as well.
The system has been running from a DOS PC for over 20 years without problems. The relays are at the load. The relays are mounted in standard metal electrical boxes with LED indicator light which is a LED shunted with a resistor in series with the relay coil. This way I can tell if it is on and the relay actually has power. It was much more cost effective to mount the relays at the load and wire with smaller wire.
The 24V power supply is is set at about 26V. My low voltage wiring is rated at least 600V to meet the inspectors requirements (low voltage must b e suitable for the highest voltage in the enclosure).
My primary concern was readability, not cost. I used commercial relays rate at 20A 277V for most of them, some are larger.
What internal safety features do the propane heaters have?
What does the propane heater do if
the propane heater runs at full thermic power = propane-flames on maximum power
the propane-heater-fan switches off accidently?
You should measure the current that the relais coil draws when the relay is switched on
A relay that is powered with 5V needs quite some current to create enough power to switch. Your picture states coil current 190 mA per relay
on 12 relay this is 12 x 190 mA = 2.3 A.
You should not argue I don't switch them all at the same time. Your code or circuitry can fail and then it does happen.
So you need an extra power-supply for the relay than should be able to deliver 25% more current than your maximum. Something like 5V 3A.
The relay is rated 250V / 10A and you are switching 2.7A.
Anyway these cheap relays are not likely to last very long when switching AC currents. You should consider using this kind of solid state relay
There is only the signal input-current with approx 10 mA. No coil-current.
Still you should use an extra power-supply.
