# [Wet Thumb Forum]-What wire?



## Roger Miller (Jun 19, 2004)

I'm about to wire a new 4X32 watt hood for my 55 gallon tank. I planned on using 16 guage solid wire but that turns out to be very difficult to find. What kind of wire have the rest of you used?


Roger Miller


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## Roger Miller (Jun 19, 2004)

I'm about to wire a new 4X32 watt hood for my 55 gallon tank. I planned on using 16 guage solid wire but that turns out to be very difficult to find. What kind of wire have the rest of you used?


Roger Miller


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## imported_Nathan (Feb 17, 2004)

WorldofWire.com has 16 gauge in both Teflon coated and PVC coated in 1000' lengths.


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## Roger Miller (Jun 19, 2004)

I can get it locally in 500' lengths. I need 30 feet. Tops.


Roger Miller


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## gsmollin (Feb 3, 2003)

All you need is 20 gauge stranded appliance wire, assuming the power factor of your ballast isn't below .3. You should be able to find that at any number of home centers or an electrical supply store, and buy it by the foot. Don't use solid wire, and don't use Teflon insulated wire, unless you can guarantee it won't get pulled around a corner.


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## Roger Miller (Jun 19, 2004)

Thanks. That's helpful. The ballast came with solid wire leads. Why shouldn't I use solid wire?


Roger Miller


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## gsmollin (Feb 3, 2003)

Sorry to hear about that. They really do cut corners these days. Solid wire has always been frowned upon in appliance service, because of the tight corners it goes through, and susceptibility to fatigue failures under vibration. I suppose in an aquarium hood application, there will be plenty of room to go around corners (minimum bend radius = 5X wire radius for solid), and vibration is not an issue, so it isn't a killer problem.

Usually appliance wire from an electrical shop is stranded, for those reasons. The appliance repairman may be re-wiring a washing machine, where vibration is an issue, for instance. In an OEM application, every cent may be squeezed out, so your ballast OEM used cheaper wire.


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## gpodio (Feb 4, 2004)

Roger, while you can use both, there are some pros to solid over stranded for lighting purposes. First of all solid wire has slightly less resistance compared to stranded, if it's a long run then this could reduce bulb efficiency, but very slightly. Solid wire also takes longer to corrode in presence of moisture. Solid wire can be bent in a housing and it will stay there and not flop around, this is important for many lighting setups where stranded wire would have to be supported to something to avoid it sagging and possibly coming into contact with the bulbs or ballasts. A solid conductor also maintains a more steady resistance when heated compared to stranded, hence solid wires are commonly used in hot situations such as electric pilots for ovens and most industrial lighting setups.

You've heard all the negatives already, it does break if bent too much, doesn't take vibrations too well and shouldn't be pulled through a raceway or other tubing.

If flexibility is a must then stranded wire is your best bet, otherwise I would use solid inside the canopy and stranded from the canopy to the remote ballasts (if the ballasts are remote that is). Also remember that most flourescent accessories are made for solid wiring, end caps for example have a hole where the solid wire is pushed into it and a metal clip digs into the wire to hold it in place, stranded in this situation may come loose as the metal clip would be placing stress on single strands rather than the entire copper wire. If you use stranded, tin the ends prior to inserting them into the end caps with a soldering iron.

Not sure if these guys have a minimum order quantity or not:

http://www.harringtonlights.com/products/fluorescent_repair_parts.htm

Hope that helps
Giancarlo Podio


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## Roger Miller (Jun 19, 2004)

The hood is wired now, but your input is appreciated anyway. I went ahead and used 18 gage solid wire primarily because the connectors appeared to require it. I suppose I could have tinned a stranded wire but it seemed like extra work for little gain. I probably would have to use finer wire to get the tinned end into the connector and the tinned wire may not be strong enough to push firmly into the connector.

Pictures will follow later.


Roger Miller


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## gsmollin (Feb 3, 2003)

First of all, stranded wire does NOT have slightly greater resistance, compared to solid wire. I don't know where this urban legend comes from, but I've heard it before. Actually, in most situations, stranded wire has less resistance. Lets look at the numbers. Solid AWG 20 wire has a nominal diameter of .0320 inches, and a cross section of 1020 circular mils. All AWG 20 wire has this cross sectional area, stranded or solid, so nominally they are the same. The difference comes from the platings. Solid wire can be plated, or not, but the platings tend to have the same thickness. So a solid plated wire will have slightly greater cross section, from its plating (tin or silver). Each strand of stranded wire is plated, and there may be many strands, typically at least 19. The plating thickness of each strand is nearly the same as the plating thickness of the solid wire, so the plating cross sections of the stranded wires add up to more than the plating cross section of the solid wire. The difference won't make you rich. A typical solid AWG 20 wire has a resistance of 10 milliohms per foot at 20 degrees C. The stranded wire has 9.1 milliohms per foot, and the difference is the platings cross sectional area (silver in this example). This is almost never an issue in equipment design, and is usually ignored.

The corrosion resistance issues are more complex, and solid may have an advantage, depending mostly on the platings. However, if you are corroding your wires in the aquarium hood, you have bigger problems elsewhere.

Solid wire can be bent in a housing and it will hold its shape, this is true. However, this is a disadvantage for solid. It is so stiff, that the wire will put stress on the electrical connections, stranded does not. The wires in the hood must be properly supported, whether they are solid or stranded.

The temperature coefficient of resistivity of solid and stranded wires are identical. It is a property of the copper. Stranded wires are also commonly used in hot situations, such as ovens and stoves. The choice between the two is predicated on other issues.

Compatibility of the wire with connector terminations, such as a lamp socket, IS a good reason to choose solid or stranded wire for the interconnects. Some lamp sockets are designed for stranded, and some for solid. This is an issue you will have to resolve. Remote ballasts need stranded wire, and that could pose difficulties with mixing solid and stranded wire in the fixture.


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## Fedorov (Apr 16, 2003)

gsmollin how do you know so much about wire ?


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## gsmollin (Feb 3, 2003)

I've been using it to design and build industrial, power, and aero-space electrical and electronic equipment for longer than I will admit to.


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## imported_pineapple (Apr 28, 2004)

I print out some of these threads for future reference and this is in my collection. Thanks gsmollin.

Andrew Cribb


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