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nmonkman

SPT 1 vs. SPT 2 wire

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Okay, SPT 1 is rated for 7 amps and SPT 2 is rated for 10.

Trying to save money, I bought both and use the SPT 1 for areas where I have less lights. One area that I keep having problems is my "little trees".

The have 12 sets of minis each (1200 lights) so that should be somewhere around 2.5 amps, right?

The cords have failed 3 times. I run them from my garage out to the yard. I have a old towel over the cords so the garage door does not cut into them. The bottom of the door has a thick rubber gasket also, so the towel is just a back up.

I was not using the towel at first because I thought maybe the door was causing it. I have looked at all 3 cords very carefully and do not see any cuts so I cannot see and don't know where any breaks are at, but obviously they exist. I also don't see any signs of "fusing" or melted wire.

Has anyone else had this problem? If so is just the cheap wire or what?

Any ideas would be appreciated.

Thanks,

Neil

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Neil,

SPT 1 is 18 AWG gauge. !8 AWG can carry 2.3 amps. Hers is a link that has a chart for wire load carrying capacities. http://www.powerstream.com/Wire_Size.htm


The other thing to consider is the length of the wire. The longer the wire the greater the voltage drop. When voltage drops, amps go up.

There is a cool wire size calculator, the link above has one also but it is a bit more tech. http://www.csgnetwork.com/wiresizecalc.html

I always try to go one gauge larger, this provides some buffer for adding lights and adds a safety factor in. Also remember anything plugged into the circuit that has any corrosion will increase the amp draw.

Hope this helps,

Lee

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Neil,

Forgot to include this in my response, I assume you are tripping a breaker or blowing a fuse based on the wire size and amp info you provided. ?????

Are you tripping a GFCI?



L

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It only seems to happen on the "little trees" that have 1200 minis on them. I have SPT1 on the roof lights but I limited it to 500 per cord.

It may very well be the amount of lights. I am running 1200 sets of minis per cord on the mega tree which is SPT2 wire and have had no problems there.

Also, it did not start occurring until I added an additional 300 lights to each set of little trees, now that I think about it.

Maybe just a second cord on the same channel until I can upgrade to SPT2 all around next year.

LIVE AND LEARN, right?

Thanks for the info.

Neil

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Jeff,



Your right on about the number after SPT (Stranded Parallel Thermoplastic) 1,2, or 3 representing the insulation. 1 being the thinest and 3 thickest.

As was explained to me generally a larger AWG will have a thicker insulation around it.

I looked into using this wire and was told by the electric supply company the spec showed 1 was 18 gauge. Maybe that's just the brand they carry. I decided to go with 14 AWG on most of the display.

Merry Christmas,

Lee

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Neil,

How are you terminating your SPT? cord for your mini trees.

It might be as simple as a vampire plug that is becoming "loose" and not making good connection. Are you reusing the same plugs on the new wire? I started using the SPT cord this year and early on had some issues with matching up the plugs and cord. This mis-match caused flaky connection issues. Even after a proper match still had some that I simply removed the plug, cut off the wire an inch or so and reinstalled the plug.

Keeps us informed on what you find.

Chuck

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Well, I found the problem and the winner of the mystery was the last post previous to this one.

It was not actually the vampire plugs, but rather my improper installation of them. Here is how I figured it out.

The lights were going out at night during the show and I would quickly replace the entire cord. Yesterday I laid the cords ("bad ones") out in the driveway and plug them in one at a time to find the break with my LiveWire tester.

To my surprise, they ALL worked all the way through the entire lenght including the female plug end. At first I was dumfounded thinking that I had checked the wrong cords. Then it hit me.

EXPANSION AND CONTRACTION!!!

I pulled one apart very carefully so as not to disturb the wire to check my theory. Sure enough the vampire tooth was barely embedded in the wire. That explained why they would work in the day and not at night. At night they must have contracted and pulled away from the tooth.

This was also a blessing in disguise because we all know that loose connections can cause fires. I am in the process now of checking every single female plug end to ensure they are right.

Thanks for all the help and ideas!!



Neil

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