Metal-case LED scrubber light safety

SantaMonica

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With the increased usage of natural algal filtration such as algae scrubbers, comes the increased usage of illumination to make the photosynthetic filtering process occur. However a certain type of light has come onto the market, and this light needs to be addressed because it is potentially unsafe when used on ATS algae turf scrubbers. If you do not have these lights, then you can decide whether to get them or not. If you already have them, then you can learn how to protect yourself.

The following posts are one person's professional opinion on the safety of these algae scrubber lights. You should consult your own professional advice and opinion from an independent electrical engineer, electronics engineer, electrician, or safety technician.
 

SantaMonica

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The lights are typically used when people build or buy the waterfall scrubber design we invented in the year 2008.

The light is a metal-case LED lighting fixture that is bolted on, and is typically made in China and sold online, but it could be made anywhere. It is designed for gardens and patios, with some rain, or for indoor growing areas that get no rain at all. See photos.
 

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SantaMonica

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We at Santa Monica Filtration were the first to test and use these types lights on waterfall scrubbers in the year 2010, as a way of getting away from fluorescent bulbs. Here is a side-by-side test of LED vs CFL in 2011:

https://www.youtube.com/watch?v=LKcib4YaoTc

The LED lights at first were expensive and cost $150 for one set shipped from China. But the pink plant grow colors worked well, and the heat was less. The lifespan was also longer, and it was not fragile to ship to customers. So we started using them on our first waterfall ATS algae scrubbers, which we invented in the year 2008; here is the acrylic box with a bottom shelf for the lights to set on, and a top shelf above the lights for protection. See photo.

Currently, all waterfall scrubbers for sale by others use this same open source free-to-copy waterfall scrubber design because it kind of works, and because the design was given away for free by us. It has problems, but again, its free to copy. And almost all pre-made scrubber builders also now use those metal-case LED bolt-on lights, mainly because they now cost only $5 but that's INCLUDING shipping from China. This makes the cost of those pre-made scrubbers artificially low, because they dont have to make the lights safe (or even test the lights for safety), and this transfers the electrical risk to you, the customer. This typical Ebay listing of 20 lights for $99 even says "U.S. stock" to make it less apparent that they are from China. See photo.
 

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SantaMonica

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Having invented the waterfall scrubber design in 2008 (water flowing down a screen), we are fairly familiar with how the scrubber works. And how the lights work too. Many people DIY their own scrubbers, and for these people the metal-case LED lights are fine to use as long as safety is observed. This is because DIY people tend to have experience with electricity, water, etc, and they are trusting their own skills to make things safe for themselves. If something goes wrong, only they get hurt. But commercial makers of scrubbers are expected to provide a safe product, because it will be purchased by consumers who are not expected to have experience in electricity. We dont use that waterfall design anymore, even though we invented it. Nor those lights. Heres why, with a focus on the safety:

The biggest problem with those lights is the fact that a line voltage of 240/120 volts comes directly into the metal-case light which is a non hermetically sealed compartment; and the light is placed within inches of splashing saltwater and salt-creep that comes out from the top of the scrubber. The scrubber is then placed on top of an open saltwater sump, where there is more splashing and more salt creep. The sump is almost always under a tank, with a simple front cabinet door that lets light out; larger tanks with sumps like these are usually located in a common area of a house such as a living room. Where children play. And its commonly known, and almost predictable, that the floor area in front of the sump gets wet, even when the cabinet door stays closed. It does not take much to imagine ones child opening the cabinet door to see the pretty pink light, and then trying to touch it, while standing on a wet floor at the exact moment that that salt creep has shorted the internal 240/120 volts of the light to its metal case. So, the idea of writing this information is to prevent this from happening.
 

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As an electrical engineer (BSEE), people like me are sometimes asked to be expert witnesses in court cases about electrical safety liability. In the USA, electrical safety is tested, and accepted most readily in industry, by Underwriters Laboratory (UL). Unfortunately this testing is expensive, and if a Chinese LED light maker pays for the UL certification, the cost of their lights will be much higher (and the certified product will have a eXXXXXX number on it). But UL certification shows that a third party has inspected the power supply to be safe, instead of just the maker of the product saying its safe. Also unfortunately, none of the Chinese LED lights described above are UL certified, as far as I know. This problem becomes bigger because the metal case of the light (metal is needed to remove heat) is what protects the wires and electronics inside. However this metal case in not hermetically sealed (not truly waterproof), and indeed because of the $5 cost it is often rushed through assembly where even the rubber seals are incorrectly inserted, or forgotten altogether. Here is an example "waterproof" light from ebay, fresh out of the box; you can see the "waterproof" seal on the 240/120 volt wire is completely not sealed. See photos.

There have been cases on aquarium forums, and on youtube, where the metal compartment screws have not been tight, or were missing. Ground wires were loose, or just cut off. Internal drivers loose and rattling around. Heat sink compound too thin or missing, causing overheating and melting of wire insulation, and even causing steam from water that was splashed on it. Because of this, its my personal opinion that using these metal bolt-on LED lights is potentially unsafe in the saltwater environment of scrubbers which are setting on sumps. Googling chinese led light danger finds too many results to read, but here are typical ones:

 

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SantaMonica

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For people not familiar with salt creep (maybe you only have freshwater), it gets into everything. Any crack, surface, or other area inside a sump will eventually get at least a light coating of salt creep, even if the direction of the surface goes upwards. Areas closer to the sump top will get a coating that you can wipe with your fingers, just like dirt on the ground. Areas on the top rim of the sump where scrubbers are placed will get coatings thick enough to require scraping tools. And salt creep is always wet, so yes, its very conductive of electricity. Its the single biggest cause of shorted-out power sockets in sump areas. Any 240/120 volt electrical device in a sump area needs to be hermetically sealed, or else it will eventually get salt creep into it. It might take months, or years, but it will happen. Here is an example video, and an example photo is attached:



And here is a more thorough description of residue build-up, which is similar to salt creep but occurs in freshwater too:



What does hermetically sealed mean? It means it's air-tight. And if it's air-tight, it's waterproof. It would be difficult to make the metal-case lights air-tight, because you would have to basically weld the case together. The most common way of making electronics air-tight and waterproof is make them a solid component.

All other aquarium sump equipment has the 240/120 volt area hermetically sealed: power heads, heaters, etc. The metal-case LED lights that are being used for algae scrubbers by some people seem to be the only equipment not sealed properly.
 

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SantaMonica

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Related to salt creep, is corrosion creep. Because the metal case of the bolt-on lights is aluminum, it can corrode slowly (even in freshwater) where the seal is located, especially at the top of the light where water splashes onto it. So even a seal that is designed and assembled correctly can be pushed sideways by corrosion creep, and eventually the seal will not be sealed anymore. And if it’s on the top of the light, water can now drain directly down onto the 240/120 volt electronics inside, and you won’t see it because the corrosion is on the inside of the seal area. A stainless steel case would prevent this, but low cost metal-case lights are never stainless. Stainless enclosures are used in underwater 240/120 volt pool lighting, but those lights start at $100 each. Here is a pool accent light with a single 3 watt LED inside, and it is $40; note how much stainless steel is needed to protect it (see attached photo).

1542233240615.png


The best way to slow down corrosion is during disassembly inspection: coat both sides of the metal case (where they touch together) with grease or petroleum jelly, and re-insert the seal, and re-assemble. Ongoing disassembly and inspection every 6 months is advisable. Unfortunately, each month that goes by will allow more salt and corrosion creep to occur, and the seal will only get worse, not better. And, just like the Chinese do, you might actually mess up a seal during re-assembly, which was fine before you took it apart. So be careful.

Interestingly, most commercial scrubber builders use absolutely no metal in their main boxes which hold the algae growth, because of course the metal would corrode. There are many low cost metal boxes that could be used, which would not crack during shipping like acrylic/perspex does, but builders instead take the time to hand-construct boxes out of acrylic/perspex so that corrosion will not be an issue. So why then do they allow metal on the lights (the most important area for safety) if they know it will corrode?

The reason again is simple: Cost. Just $5 to $8 each, including shipping from China. But the Chinese know that if someone is injured because of these lights, nobody will be going to China to sue them. So the Chinese have absolutely no need to make things safer. It’s up to the DIY person to check each light (by taking it apart), and it’s up to each commercial scrubber maker to request UL certification, non-metal construction, low voltage operation, and hermetically sealed enclosures.

It's my opinion that all of the low cost metal-case lights are made in China, even if they have been relabeled to look otherwise. I've spent hundreds of hours trying to find lights (and other parts) in the USA, only to be directed to China every time. The cost of the metal castings for the case alone would be $10 or $20 each, if made in the USA. And the labor to assemble the electronic and other parts would be another $30 at least. So manufacturing in the USA is not an option for these types of lights, and if they say “Made In USA” you should assume this is not true. This was yet another reason for us to abandon these metal lights (and their internal electronics design). But even if the bolt-on metal Chinese lights were made in the USA, and even if they were UL certified, you still have the problem of the electronics enclosure not being hermetically sealed. So if water, or steam, or salt creep gets inside, and you touch the metal case, it’s not going to matter who made it, or who certified it, or what the warranty is. The 240/120 volts should be 2 meters away from the splashing and salt creep (see attached photo).

2 meters.jpg
 

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SantaMonica

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Some people will say, "These lights are safe, because they were made for outdoor use in the rain".

First of all, this is assuming that the lights were put together correctly in the first place. Open up a few and check for yourself to see if the ground is connected properly, or if it was just cut off completely. If it's not connected properly, you can forget any safe usage, anywhere. As a matter of fact, if the ground is not connected properly, usage in the corrosive saltwater environment of a sump is (at least) very dangerous, and in my opinion could be described as deadly, when the operator is an unsuspecting and non-electrically-aware consumer (or worse, their children, standing on a wet floor) who bought the scrubber thinking the manufacturer did all the proper safety designs and certifications.

Second, even if it was put together correctly, usage in an outdoor area or garden usually means the light will be staked into the ground, or will be attached to a metal conduit, both of which provide a ground path if the internal 240/120 volt circuit gets shorted to the metal case. Plus, you don't normally touch, grab, or usually even go near these outdoor lights in a garden. So even if they shorted internally to the metal case, and even if the ground wire were missing, you would not be anywhere near it.

Third, the water falling onto the lights in a garden area is just freshwater. Compare these things to a saltwater sump:

It's bad enough that the ground might not be connected, but regardless, the installation is on the top of sump that is not grounded. It's not a garden bed, and it's not a metal conduit grounded to a house. Instead it's an electrically-floating acrylic box filled with water. It's a really, really bad place to have a possibly non-grounded product, or even a grounded product that is likely to eventually leak.

And the usage requirements of these scrubbers requires weekly, and sometimes daily, touching and grabbing of the lights. With wet hands, and while standing on a wet floor. Ask any licensed electrician if he would like to be doing this.

The 240/120 volt power supply in these lights is inside the metal case which holds the rubber seal in place. All metal corrodes, especially aluminum, and especially in saltwater, and when the metal corrodes enough around the seal, the seal will leak. And the most dripped-on part of the light is the top, and that is directly above the internal power. So, the water drips down directly onto the high voltage inside. Look at how the lights are usually mounted: the seam of the seal at the top is directly over the internal power supply.
 

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Another problem with most of the metal 240/120 volt lights, is that in order to save more money, they often make the 240/120 volt cord very short, usually just a few inches (see photo).

240-120 led light short wire.jpg

This means that the rest of the 240/120 volt wire needs to be connected at this point, and almost any connection made by anyone is not going to be hermetically sealed. This connection is going to be placed directly over open areas of sump water, and therefore it’s going to get a lot of salt creep and even direct splashing. There is no fix for this; the wire should be replaced entirely.

If you are going to DIY and already have a set of these metal-case lights, you are best advised to not use them and just get a safer light instead. At the very least, use a GFCI protector, available at any hardware store. A safer option would be a low voltage DC version of the same light, with a remote power supply that either comes with it, or that you get and connect yourself (just make sure to get a UL certified supply if it's for the USA). With a really long 2-meter DC cord, the 240/120 volts can at least be placed far away from the sump. However, this does not solve everything for these metal case lights.

Splashes from the sump, and from the top of all-in-one nano tanks, can easily reach the power supply box especially if the box is kept in the sump cabinet or behind the cabinet on the floor. A splash (or even very thick wet carpet) can short the 240/120 volt AC side of the box to the low voltage DC side, effectively electrifying the "safe" side to 240/120 volts.

These low voltage DC lights typically are not grounded on their DC side, so when the 240/120 volts hits the LED diodes inside, the diodes are either going to fail open, or fail closed. If you are having a bad day, they will fail closed. The lights typically use Chip-On-Board (COB) designs which put the diodes within one millimeter of the ground plane, and a 240/120 volt shorted diode will easily arc to the nearest piece of metal which is probably now going to be the metal case. So you once again have a 240/120 electrified case waiting to be touched in your sump area, and you will no doubt be touching and grabbing the light to inspect why it is no longer turning on. Thus even low-voltage metal case lights can be electrocution hazards.

The metal case of these lights is a major problem for safety. Metal obviously conducts electricity, and any 240/120 volt wire that touches the inside of the case is going to electrify the case and cause an electrocution hazard. Especially when you remember that the floor where you are standing is often, and predictably, wet. Unfortunately since the metal case is also the enclosure for the electrical parts, there is no DIY or pre-made solution for this. All you can do is disassemble each light and inspect for visible problems, and test for electrical safety. And if you don’t know how to test, get an electrician to do it for you; the metal case must be grounded to earth.
 
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