I have about a dozen door sensors (normally closed) wired up that I'm feeding with 5v, and the other side is wired to various digital pins with a pull down resistor. I also have about four photo resistors I'm using for light sensors. Each light sensor is also wired to 5v, and the other side an analog pin with a pull down resistor. Should be very simple circuits right?
Recently my ethernet shield died, or at least started to brown out. A spider built a small web on my Arduino (it's in my crawlspace). so it may have had to do with that? I want to make sure that my wiring isn't stressing out, or pulling/pushing too much voltage that would fry my Arduino, since I just bought a bunch of replacement parts.
It's all about the total current draw your external components are drawing from the arduino 5V pin. So what are actual number and value of all your pull-down resistors? How many sensors and what are their current demands? How much current does your Ethernet shield draw? When you have that all calculated or estimated then you can look at the 5V current capacity (different if USB Vs external power is used) you can tell if your hitting a limit and need a change of design, such as supplying 5vdc current with an external power supply rather then from the 5V pin. It's not rocket science but it is basic engineering.
A spider built a small web on my Arduino (it's in my crawlspace). so it may have had to do with that?
Spider webs are non-conductive. The spider itself probably has some very-high resistance (I think you can electrocute a spider with enough voltage) but in a digital circuit it's not going to cause any trouble. Now.... if a mouse urinates on the board it might be damaged, but probably more by corrosion than by conductivity or "shorting-out".
