Jump to content
Top Shelf Aquatics

Will I burn down my house?


magnetar68

Recommended Posts

A little over a year ago, I started a DIY LED build (

DIY LED Design for 48"X24"x24" Tank). I got it up and running, but never did the final touches to call it done. I have been using a second-hand MH fixture, but it's time to finish my LED build. I have a couple of questions.

 

1) I used a data cable to run all of the wires from the project box to the LED fixture. I used a 9 wire data cable (only using 8 wires: 2 for XP-E Blue (700mA), 2 for XP-E Royal Blue (700mA), 2 for XP-G White (1.0 Amps), and 2 for the 12V 500mA fan). These are 24 AWG wires. They are attached to Meanwell ELN-60-48Ds. So call it 28V DC at 1.0A.

 

Can I get away with running these over a 6ft distance? I know a higher gauge is better (say 18) as it offers less resistance, but how much trouble am I asking for here? [i will not hold anyone liable for answering this question]. Is it just inefficient (energy loss to minor amounts of heat and increased Voltage drop)? or could I melt wires and start fires at these operating parameters?

 

2) I have my own project box (shown below). How bad is it to take off the meanwell plastic covers and wire covers and just mount these naked inside of my own box? Again, am I asking for trouble if the box if well ventilated? It does not appear the stock enclosure offers any shielding or heat management.

 

2011-07-14_17-53-38_602.jpg

Link to comment

Simply put most likely you will melt the insulation and short out some wires probably burning out your driver.

Normally data cables have around 1/4 mm insulator around each conductor and a wire rated to about 150 degrees Fahrenheit. The 24 AWG data lines by spec are rated to a maximum of 500 mA. Considering 12 feet of conductor for anode and cathode the resistance would be 0.31404 ohms. Following Ohms law that would mean 0.31404 x 0.7 (amps) = 0.219828 volts lost per two wires. That means you won't loose much voltage but you are still out of maximum specifications especially on the 1 Amp line. For the amount of time and money you put in, you need to find a more suitable wire. Leave at least 25% more than the wire gauge has for a max current. Here is a chart to help you: http://www.interfacebus.com/Copper_Wire_AWG_SIze.html

 

Edited for spelling and clarification

Link to comment
Simply put most likely you will melt the insulation and short out some wires probably burning out your driver.

Normally data cables have around 1/4 mm insulator around each conductor and a wire rated to about 150 degrees Fahrenheit. The 24 AWG data lines by spec are rated to a maximum of 500 mA. Considering 12 feet of conductor for anode and cathode the resistance would be 0.31404 ohms. Following ohms law that would mean 0.31404 x 0.7 (amps) = 0.219828 volts lost per two wires. That means you won't loose much voltage but you are still out of maximum specifications. For the amount of time and money you put in, you need to find a more suitable wire. Leave at least 25%get more than the wire has for a max current. Here is a chart to help you: http://www.interfacebus.com/Copper_Wire_AWG_SIze.html

 

Edited for spelling and clarification

 

I found a rating calculator for PVC covered bundled data cables (although, I don't know that it is for the brand I have), but is says for 24 AWG in a bundle of 6-15 wires, the max current carry capacity is 4.2A (=6 * 0.7), not 500mA. [see here MAX Current Calculator]. I am no where near certain that is correct, but I did try to find a general guidline for current and did not see 500mA. Can you help me find the source for this? You are right that this cable is 1/4mm insulation and 80 celcius, but they do not mention max current in the datasheet: Multi-conductor Data Sheet

Link to comment
I found a rating calculator for PVC covered bundled data cables (although, I don't know that it is for the brand I have), but is says for 24 AWG in a bundle of 6-15 wires, the max current carry capacity is 4.2A (=6 * 0.7), not 500mA. [see here MAX Current Calculator]. I am no where near certain that is correct, but I did try to find a general guidline for current and did not see 500mA. Can you help me find the source for this? You are right that this cable is 1/4mm insulation and 80 celcius, but they do not mention max current in the datasheet: Multi-conductor Data Sheet

 

Sorry, my bad, I see that that table you sent has the Max Amps for Power Transmission at 0.577A. It does say this is very conservative, but I will see if I can find some 4 pair 18AWG wire. I see Belden makes some.

Link to comment
I found a rating calculator for PVC covered bundled data cables (although, I don't know that it is for the brand I have), but is says for 24 AWG in a bundle of 6-15 wires, the max current carry capacity is 4.2A (=6 * 0.7), not 500mA. [see here MAX Current Calculator]. I am no where near certain that is correct, but I did try to find a general guidline for current and did not see 500mA. Can you help me find the source for this? You are right that this cable is 1/4mm insulation and 80 celcius, but they do not mention max current in the datasheet: Multi-conductor Data Sheet

 

BTW, I did see something that said that the 700 cms per AMP rule used here is more around winding transformers where heat is an issue and it is OK to use 300 instead (even 200 instead). At 300 mils, a 24AWG wire would be (20.1)^2=404.01/300 = 1.3467Amps. It seems like 1.0As gives me some reasonable headroom. I realize I am just trying to justify what I already have because its easier and cheaper, but have people run 24AWG for power transmission of these LED drivers and really seen them fry? I guess if one derates this for being in a bundle using the 0.7 factor from above, then this would put the amp rating to 0.94A.

 

Oh well, I get, I am looking into 18 guage wire options.

 

What about my second question? OK to remove the meanwell covers?

Link to comment
You can consider braided wire wrap similar to this. It looks very professional if you get the right size and install it correctly.

 

http://www.amazon.com/Painless-Wiring-7091...t/dp/B001P29XZK

 

What would your guess be for an eight (8) ten (10) 18AWG bundle in terms of the PowerBraid diameter? If I go with 5 pairs to add connectivity for 1W moonlights, then I think an 18AWG wire is about 0.92" in diameter, so 10 wires would be 0.92". Does that sound right? I need 1" PowerBraid to make the data cable?

Link to comment

,

Honestly just get heavier wire and then look into some braided wire wrap. I am running a lot of wires... fan 3 temperature probes, PWM for dim, fan control, led power x 2, mods for salinity and Ph and an extra set for future use, powerhead, moonlights, fuge lights, all set up for a microcontroller. I am used electiduct as they were cheap

Link to comment

Archived

This topic is now archived and is closed to further replies.

  • Recommended Discussions

×
×
  • Create New...