Electrical Safety Relating to Reptiles

Hopefully this will help some people out and I want to refute a few things I hear repeated through out the hobby. I’ll try not to just tell you what to do, but why we do it. I’ve been doing electrical for a living for 13 years. I also would like to open this thread to anyone who would like to ask any electrical related question. If I do not know the answer personally, chances are I know where to find it or know someone I can ask.

Receptacles
Yes the ones in your wall. If I plug something into it, does it fall out easy? Does a light tug make it pop out? Does it look a little limp plugged in? That means the spring tension on what holds the blades inside the receptacle are weak and you have the potential of a fire hazard. Loose connection creates more resistance, resistance creates heat, heat creates more resistance, resistance creates more heat, the cycle continues til something burns up or melts. Now with that said, it takes the right conditions to have a disaster, but just do yourself a favor and not allow those conditions to happen. Replace the receptacle. Use your own judgement on if you need a professional to do this for you or you can DIY it. I bring this up first as I feel this is one of the most common hazards in households today, parts are cheap, and you can visually see it easily.

GFCI/AFCI
GFCI will only be required if you have a sink or such in your room. However, they aren’t a terrible idea. GFCIs got a bad rep from their early iterations, where they had a lot of nuisance tripping or tripping when they weren’t supposed to. Newer gfcis hardly have that issue now. GFCIs work by monitoring current between the hot and neutral wires. If the difference becomes more than 5ma, it trips. So if a lead pops off your heat tape and you reach back there to feel if its heating up, you might get railed. Spill some water and bend down to clean it up and touch a plug hanging half out the receptacle, not so fun times. The GFCI will trip and potentially save your life. In my opinion if you want the top of the line protection, get a GFCI/ACFI breaker to feed your room. They are extremely expensive comparatively. usually 50 bucks vs 3 dollars for a normal breaker. However you will have the above protection plus arc fault protection, which can detect arcs and trip before something happens, like a wire falling out of the back of receptacle for example. Both people and equipment (and by extension animal) protection.

Surge Protectors
A surge is just an unintended increase in voltage. Most of the time id say lightning is the cause, but can also come from utility doing grid switching and even small surges can be caused by compressors in your fridge or a/c units. Electronics are most likely to have issues from this increase in voltage. In the reptile world, basically our thermostats. Surge protectors will bleed off the unitended spike to ground, keeping everything after it from seeing that spike. The amount of protection it can provide is rated in joules. once you surpass this, it will no longer protect any device. So this is where the problem lays. Most peoples only surge protection is a power strip with surge protection built in. They tend to not have an indicator of when the surge protection is toasted. So they will work until they don’t and you wont know when that is. The other scenario is it does have an indicator on it and then you leave it behind a cage and never see it again until you are plugging in a new cage. So if you get one, I highly suggest you get one with an indicator on it and actually check on it once in a while. Other option is to go the lazy route and just have a back up thermostat ready to be installed in case of failure.

Thermostats
Depending on the thermostat, this could be the weakest link in your electrical system. They come in varying ratings, Ive seen them low as 150 watts and some go up to 1500w. Just something else to be aware of some you don’t overload anything.

Generator
Generators are a great thing to have. I do want to mention some of the thermostats in the reptile world do not take kindly to less than ideal power, which your average generator is defiantly less than ideal. Test your generator with your thermostat before relying on it. If you do have this issue, my suggestion would be to have a simplier thermostat that doesn’t have issues to use with the generator or have something mechanical like a rheostat if you are comfortable dialing one in.

Stuff I’ve seen on facebook:

Here is some background information that might be needed to understand some of my comments. Most residential general circuits are 15 amp. I think it could be fair to say most peoples reptile rooms would fall under the definition of continuous load, which is running at full power for more than 3 hours. This means we need to reduce our capacity to 80% or 12 amps according to the code book. So in a typical situtation we dont want to be pulling more than 12 amps. Most things are rated in watts though. So to make it easier we will use the forumla for power, amp x volts = watts, 12a x 120v = 1440w. thats is the maximum amount of power to pull on that circuit. This is the most common scenario for a house in the USA.

“You can’t plug multiple power strips together, it will start a fire!”
You can plug in as many as you want to each other, it’s called daisy chaining. This is done professionally when you need a ton of flexibility of moving power around, generally temporary like an expo show. There’s nothing dangerous about that itself, but we have more to discuss. An electrical system is only as strong as its weakest link. Your house has 1440 watts available on that circuit, but what is your power strip rated for? Most today are rated for 15 amp, however I’ve come across some only rated for 1000w (8.3 amps). There are also some without ratings, which then you cannot tell what it is capable of. Then the other part is just not overloading the circuit by plugging in too much stuff. Know the wattage of your devices, 1440 watts max on a 15a circuit. However the amount of daisy chained plug strips doesn’t matter one bit. Also like receptacles above, make sure it is actually holding what you plug in, it should not be loose.

“Don’t plug multiple extension cords together, it will start a fire”
Same as above, check ratings. Nothing wrong with multiples With one more tid bit to add. The longer your cords, the more resistance there will be, eventually this will start affecting the amount of power you can safely run through it. A 25 foot cord in a room is minimal and nothing to worry about or 2 10 foot cords plugged together. Feeding an out building from 200 feet away, you might have to use a heavier gauge extension cord to safely do so. Many variables come into play here, but it is something to look into depending on your situation. Just don’t think plugging a few short cords together is dangerous for some magical reason.

“Hook your flex watt up in parellel instead of series”
Well lets start with there is only 1 practical way to hook up flexwatt and that is in parallel. To hook it up in series you would need to cut each individual heating element (the black bars) and wire them up in series individually. No one does this, so series just doesn’t happen, and it wouldn’t work anyways. What they are referring to is using the buss bar (the foil strip on each side) as a feed through, hooking wires on one end of the tape to power it and taking wires off the other side of the heat tape, to go to another piece of heat tape. You shouldn’t have to worry about this unless you have a big rack system. The flexwatt I use is 4 watts a foot and has a max length of 40 ft. so 160w or 1.3 amp total. If I am running more heat tape than 40 ft, I will need to make sure I don’t feed through all of it or I could surpass the heat tape rating. Other than that, it should make no difference. Some people claim the resitance of the buss bar will cause variations in temperature, while technically true, the difference is so minimal, you’ll never notice it. The low power and relatively short runs make this not even worth discussing. Just know your heat tapes limits and stay below them. The heat tape most of us use doesn’t have scentific precission. There will be variations no matter how you hook it up, they should however be minimal.

To appease the die hards of “I’ve tested it and it makes a difference.” Well I did the math (to a point) and here is what we are looking at. Yes I’m rounding when I can for simplicity, no I am not considering every single electrical concept to be calculated, just what I feel is enough to get rid of this repeated “advise.” Judging by the buss bar’s ampacity rating it is the equivalent of something around a 26 awg wire. 26 awg has a resistance of 133 ohms per 1000m. Generally I use 18 awg to wire heat tape. 18 awg has a rating of 21 ohms per 1000m. So yes we can say 26 awg has over 6 times the amount of resistance of 18 awg. However we need to look at the whole system. Lets get the resistance values into something we can use. 133 ohms/(3280 * 12) = .00338 ohms per inch. 21 ohms/ (3280 12) = .00053 ohms per inch. Heat tape is 4 watts per foot, using some algebra on ohms law, we can figure out resistance. ohms = volts² / watts. ohms = 120²/4 =3600 ohms per foot. Heating elements are in parellel, so using the formula to figure out the resitance per inch, “1/Rt = 1/R1 + 1/R2 + 1/R3…” and a little alegbra, it can be simplified as 360012 = 43200 ohms per inch. So removing the power delivery, we are left with the heating elements having a resistance of 43199.996 per inch. So basically still 43200 ohms per inch. Are we starting to see how insignificant it is now?

To keep going, I’ll compare feed through (what people call series) or daisy chaining (what people call parallel) on 10x 4 foot sections to the farthest heating element. Feed through will be additive. 10x sections of 4 foot @ .00338 ohms and lets say 6 inches of wire in between each section @ .00053. total of .03857 ohms. Daisy chaining will have 54 inches of wire and 4 feet of buss bar (.00815 total). Daisy chaining has about 4.7 times less resistance compared to feed through to the farthest heating element. However arguing between the two when the heating element is 43200 ohms, is absolutely ridiculous. To push it farther you would calculate voltage drop and I guess average it out throughout the entire system as we have practically 400 devices we are powering. But to debunk the variation claims, the first heating element in both systems is 43200 ohms, in daisy chaining the last element is 43200.00815 ohms, and in feed through the last element is 43200.03857 ohms. This difference will have no noticeable effect on temps.

Its like arguing the shipping cost being $60 dollar instead of $59.99 on most expensive snake you can think of. Yeah that kind of insignificance. The manufacturing variation of the heating elements will probably have thousands of times more difference than how it is wired. If someone legitly had a difference in temps, I would assume manufacturing defect of the tape or less than ideal connection to the heat tape. So besides making sure you don’t exceed the heat tapes rating, wire it just however is convenient for you, a lot of times daisy chaining is just easier.

Did I miss any electrical myths?

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This is EXTREMELY useful Matt. Thank you for sharing this here.

Considering I’m not fluent in electrician lingo, you made it easy to understand and follow :blush:

My rack is on the opposite side of the room to the plug sockets so up until a few weeks ago I was daisy chaining 2 extension leads around the edges of the room. Because I believed that it was dangerous I went and bought a single extra long heavy duty one (the type that construction workers use outdoors). It’s nice to know that it is a myth though, now rather than having a second wire going all the way around my room when I need to add additional racks, I know I can just plug them into the original extension.

:+1:

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