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R.j.D 08-13-2012 02:36 PM

hi I am new here and need some help. once i registered i see everyone here are mostly pro's and i am not i just need some help so please dont mind my question, because I am a beginner. I am trying to find out the Load on electrical line. let me explain so its a little easier to understand. During the holiday season I have quite a large holiday display at my house, I have a bunch of items I put on my roof and run about 30 really heavy duty extension cords from my roof to the ground close to 100 feet long. Might I add there really heavy. I wanted to make my own extension cords at of STP2 wire but I was told I need to know the load for the wire. So I don't even know how to find out what the load is on the wire. Each extension cord that goes up to the roof only powers one item each, for example one wire might power a 1 foot tall snowflake with 100 incandescent bulbs on it, another one would power a wreath I have on the roof with hundred LED lightbulbs It. So I hope to God I am making some kind of sense. Can someone please tell me if there's a tool I need to buy simply tell me what the load is, or if there's an equation to figure out what the load is..... So I can figure out what type of extension cord I can use. I definitely don't want to keep using the really heavy gauged heavy duty ones I presently use now.

Thank you

kevinp22 08-13-2012 02:44 PM

To determine the load (amps) you do the following:

Number of lights X watts per light / 120

So if a fixture has 50 7 watt bulbs you are looking at 350 watts or 2.91 amps.

If you are using extension cords rated for 15 amps for that you are looking at serious overkill. However, whatever cords need to be rated for outdoor use

I dont do holiday lighting on the house (my wife wants me to and I come up with a different excuse every year) but there has to be an easier way to distribute power to an area than one cord per fixture

ddawg16 08-13-2012 04:01 PM

If you want to do it the easy way.....go by a "KillOWatt" meter. Then, jnust plug each dection into it one at a will tell you how much load each device pulls.

R.j.D 08-13-2012 04:03 PM

Thank you very much for the help, the reason each extension cord only runs one fixture is because of the bigger picture. I use a program called light O Rama. That is the program I use the program all the lights in the yard in on the house and on the roof. Each individual fixture is controlled via my computer through what we call a lighting controller boxes, I own about 17 boxes. That box has 16 dongle cords that come out of it. Each cord gets ran to a fixture and through my computer I can control each individual fixture. Whence, the reason for one cord goes to each fixture. You can take a look at my house I have my own website. ,

Anyway again thank you for your help, I will continue the question by saying I went out and bought a 600a AC clamp meter with temperature it's made by klein tools. Hopefully with a little help from you guys you can tell me how to use this piece so I can figure out what my load is.

kevinp22 08-13-2012 04:12 PM

The additional information helps. The problem with a clamp on meter is that you you have to be able to measure each conductor. If you put one of the extension cords or fixture cords under the clamp, the hot and neutral conductors will cancel out/give an incorrect reading.

Better to use the meter ddawg mentioned, then size your cords accordingly.

R.j.D 08-13-2012 04:18 PM

i just walked in from hd and i bought a ac clamp meter.....will this do or did i get the wrong tool?

kevinp22 08-13-2012 04:22 PM

Wrong tool Im afraid.

Anyone disagree?

If there was a location where the individual conductors were accessible the clamp would work but for this application the other tool seems to be an easier choice.

I ran to HD 3 times in one day a few weeks back. It happens.


R.j.D 08-13-2012 04:23 PM i always get the wrong thing...this is why hd is no good, i told the guy what i was trying to do. and he gives me this! ok back to hd. guy thanks. alot, ...will i ever need this tool. should i keep it.

R.j.D 08-13-2012 04:23 PM

buy the way the name is Ralph guys, and again, really thank you!

R.j.D 08-13-2012 04:27 PM

hey kevin, do you mind, telling me, once i get this thing, what do i do with and how do i figure out if i can use a spt2 home made extension cord and still be safe with them or will I need to stick to my really heavy gauge outdoor rated extension cords.

kevinp22 08-13-2012 04:28 PM

Its a useful tool if you do wiring. I have one. However if this project is your only foray into this stuff I would return it.

R.j.D 08-13-2012 04:28 PM

Is there any brand in particular one better than another.

kevinp22 08-13-2012 04:29 PM


Originally Posted by R.j.D (Post 987749)
hey kevin, do you mind, telling me, once i get this thing, what do i do with and how do i figure out if i can use a spt2 home made extension cord and still be safe with them or will I need to stick to my really heavy gauge outdoor rated extension cords.

Yes outdoor rating is necessary. As to the rest of your question I am going to let someone with more experience answer

R.j.D 08-13-2012 04:31 PM

While the wife would kill me but I would love to put a subpanel on my house just for all the Christmas stuff, right now I have 20 dedicated 20 amp lines around the bottom of my house outside of course and it takes up a lot of space in my present box I have. Don't worry I only know enough to break things, I would never really attempt to put a subpanel on by myself I really would have no idea what I'm doing him, I cant even figure out how to find the load on electrical Anyway backoff the Home Depot in the eyes don't mind I will pick this up when I get back. Thanks a lot guys again

biggles 08-13-2012 05:17 PM

simple amprobe will do the load readings but you need to connect all groups in parallel not series...which will effect the amps and lights.i have 100 mini bulb tree i lift onto the front of my house to the peek... all female sockets are dipped in liquid plastic and the male ends are stacked into one socket doing 3amps fused for 5 amps...sears has simple cheap amprobes when you read the amps onlt clamp one wire to read the show..then fuse it.:wink: one XMASS panel woud be easier but the install is to happen now not after T-DAY he run some underground romex to sockets ..wire tie pastic bags over sockets and your good to go:thumbsup:

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