Extension cords on the roof question

[Ralph D]

Hi everyone,

I need some advice and some help on this. I want to see what everyone's advices on this. Right now on my roof i am plugging everything into really heavy duty extension cords, I think they're 18gauge extension cords and they are really heavy hard to deal with. I was wondering if it would be ok to make my own extension cords with SPT- 2 or even SPT-1 wire and just put my own Ends on them. Right now I have over 20 extension cords up on the roof each courd is its own channel , 16 of them are just for running my 1 foot tall incandescent snowflakes, four of them are for my 9 foot tall wreath that is 4 colors, 4 are for the roof board lights, and the rest are for the wire frames i put on my roof . I am really hoping it's going to be okay to make my own extension cords and use them on the roof, are there any con's to doing this and electrically speaking is it safe? I'd love to hear from everyone get your advice, input, any pros or cons you might have about this idea. Thank you and I really appreciate all your help.

Ralph

[Don]

For my own home display, I've used SPT1 cords to get from the roof to the controllers on the ground. It is my opinion that if you take precautions to keep the cords from flying off the roof, along with precautions for dealing with rain/snow, you should be fine.

[Orville]

Being on the roof, you want to be sure the SPT1 or SPT2 wire you use is UV resistant or it may break down and deteriorate since it will be lying on a hot roof in the direct sunlight.

As for making your own, again, if UV resistant wiring is used, and you say each cord is it's own channel, I don't really forsee any issues with the way you're setting things up.

Now if each cord were powering multiple items {3 or more that are incandescent, LED's are a bit more forgiving} at once, then you could have an overload problem on the cord, which could actually cause it to overheat and start a fire. Something you definitely do not want to happen.

Best of luck to you on your endeveor and display set up.

But from your description of using 1 cord per incandescent item, I think you should be fine with that.

[LOR Staff]

I believe you have 12 or 14 gauge cords as SPT 1 and 2 are 18 gauge.

This is not true. SPT1 or 2 refers to the insulation type and has nothing to do with the gauge of wire.

[LOR Staff]

Now if each cord were powering multiple items {3 or more that are incandescent, LED's are a bit more forgiving} at once, then you could have an overload problem on the cord, which could actually cause it to overheat and start a fire. Something you definitely do not want to happen.

This is not true. The number of items run from a single cord has nothing to do with how many amps that cord can supply safely. For example, 3 strings of 100 ct incan C7's will pull over 17 AMPS. Factor in the resistance of how long those cords are and you'll be way over the safe limit

In order to safely run, you must know what your loads are. NO EXCEPTIONS.

[dgrant]

I'm going to be doing the same thing with SPT-1 cables up there connecting all my outside windows together. My worry isn't rain or snow, rather lightening. There's not much I can do about it and yes, should that happen, it'll toast the controllers. I've already had a strike here at the house or very, very close to it, that took out all the telephones and my fax capable printer. I never found the strike point itself but certainly heard the flash/boom at the same time and things were dead. This was early last winter.

[Orville]

This is not true. The number of items run from a single cord has nothing to do with how many amps that cord can supply safely. For example, 3 strings of 100 ct incan C7's will pull over 17 AMPS. Factor in the resistance of how long those cords are and you'll be way over the safe limit

In order to safely run, you must know what your loads are. NO EXCEPTIONS.

This is not true. The number of items run from a single cord has nothing to do with how many amps that cord can supply safely. For example, 3 strings of 100 ct incan C7's will pull over 17 AMPS. Factor in the resistance of how long those cords are and you'll be way over the safe limit

In order to safely run, you must know what your loads are. NO EXCEPTIONS.

Mike is correct. I was unfortunately interupted when posting that particular post and hit the post button.

Cord length resistance and knowing your load limits are DEFINITELY required.

Although I've been using both indoor extension and home made extended extension cords for single element items for 2+ years now, fortunately I have had no issues and I have always examined my cords for any excessive heating, wear and tear and the amperage has always been low. I always just have a single strand of incandescents (50-100 ct string) or 35ct to 200ct LED strands, and some are 3 C7 bulbs in a Blowmold and haven't had any issues. But, then again, I examine my cords all the time when in use to be sure everything is working and I'm not overloading or overheating anything.

[LOR Staff]

This is true that the difference between SPT1 and SPT2 is the insulation and that SPT1 is rated at 7 amps and SPT2 is rated at 10 amps but both at 18 gauge. (at least I have never seen SPT 1 or 2 anything other than 18 gauge). Let me know if it is out there as if so I believe the vampire plugs will not fit that wire.

Insulation thickness has LITTLE to do with the current capacity, but has a LOT to do with voltage. Your 7 and 10 amps numbers are COMPLETELY WRONG since you are basing them on the insulation size. 18AWG wire will carry 7A, and 16AWG will carry 10A just fine WITHOUT ANY INSULATION.

Yes, there are different AWGs available for SPT type insulation:

http://www.signalandpower.com/SPT-2-300V/SPT-2-16AWG-2C/

http://www.signalandpower.com/SPT-2-300V/SPT-2-18AWG-2C/

Vampire plugs are based on the INSULATION size, not the AWG. 'Normal' vampire plugs work perfectly fine on 16 AWG just as they do on 18 AWG. The insulation size matters since the tooth needs to be LONGER and spaced FARTHER for SPT-2 than SPT-1, since SPT-2 is 'thicker'.

[Guest wbottomley]

Mike... I'm going to run out of like tonight. Set the record straight bro.

[Ralph D]

Morning, yes i did forget the smaller "thinner" the cord the larger the number. right now i use the "very" thick and heavy orange extention cords like you would see at most construction sites, 100 feet each. and like i said each cord runs things like, 100 incandescent bulbs on a single snow flake, or 100 leds of one color per extension cord on my wreath. I knew from the beginning that these cords would be the safest, and quite frankly that's why I bought them and back 10 years ago I didn't care how heavy things were, and in all these past years I've always had help getting set up and getting the cords up on my roof, But this year and the years to come I know less help will be around for me. I definitely don't want to put anything on my roof that's unsafe or could start a fire, but in the same breath I'm hoping I could find something in between that's manageable for one person to work with and still be safe for my home..

I won't be using vampire plugs on these lines , I will be using the same plugs that CDI sells ,http://www.creativedisplays.com/product/472/ELECTRICAL-PLUGS-FOR-PRO-GRADE-WIRE/. I've used in the past cdi's " #F" but am wondering is #D would be a better plug to use.

I really want to say thanks for all the advice so far.

Ralph

[Ralph D]

OK how do i figure out what my load is going to be on each line then. What is the equation?

[Guest wbottomley]

If you want to be near certain on the amperage, use this.

[Ralph D]

Thanks for that.

What does everyone think about using SJ wire, my electrician just happened to be here this morning and I was asking him about it . Instead of using STP wire he suggested I use SJ wire which he told me is just a little bit more thick, better insulated and can handle bigger loads then the STP wire...... what are your thoughts.

[LOR Staff]

.....

You are confusing insulation, current carrying capacity and configuration all in 1 sentence. SJ just means it's a portable service cord, with an outside jacket that will insulate to 600v (S), with conductors insulated to 300v(J) each. STP is 'Stranded Twisted Pair', IE, a CAT 5/6 cable which has insulation that is NOT rated for power line voltages.

'Handle bigger loads' infers that the conductor is bigger, and NEITHER of those (SJ or STP) has ANYTHING to do with wire gauge. And even that is meaningless if you don't know how much load you'll have.

[Santas Helper]

If using vampire plugs, you'll want to keep the size wire in mind to fit in the vamp plugs.

Just something to think about.

As for UV protection, For holiday use, it wont be on the roof that long for this to be a concern IMHO. If you were to leave the cords on the all year long and during the hot months, then I would consider it more.

Just my opinion.

[DownTown]

.....

You are confusing insulation, current carrying capacity and configuration all in 1 sentence. SJ just means it's a portable service cord, with an outside jacket that will insulate to 600v (S), with conductors insulated to 300v(J) each. STP is 'Stranded Twisted Pair', IE, a CAT 5/6 cable which has insulation that is NOT rated for power line voltages.

'Handle bigger loads' infers that the conductor is bigger, and NEITHER of those (SJ or STP) has ANYTHING to do with wire gauge. And even that is meaningless if you don't know how much load you'll have.

Actually, STP is Shielded Twisted Pair (as opposed to UTP - Unshielded Twisted Pair). STP comes in both stranded and solid flavors.

D.T.

[Guest wbottomley]

Make the zip cord with vampire plugs, throw it on the roof, connect the lights and call it a day. This is not brain surgery. Each 100ct incandescent mini pulls .34 amps. Do the math. Plus... you are limited to 8 amps per channel to a max of 15 for each controller bank unless it has been modified.

[Ralph D]

ok MIke, got it, find out what the loads will be on each line.

[LOR Staff]

Actually, STP is Shielded Twisted Pair (as opposed to UTP - Unshielded Twisted Pair). STP comes in both stranded and solid flavors.

D.T.

You are absolutely correct. I was getting my S's confoosed!

[Ralph D]

ok bought a amp / watts meter. and my snowflake is pulling .02 amps.......I checked it twice. Pretty cool ! I also copied Home Depot's, guide. chord length vs amperage guide. But it doesn't list anything lower than 7 Amps.

What I can tell you from reading this guide and using my new meter, is at 100 feet long using a 16gauge extension cord i would be safe, even if I was pulling 7 A, but am not I'm only pulling .02 amps And if I was using a 10gauge extension cord using the same 7 A I could use a 250 foot cord.

Does anybody know the rating of the STP2 wire . I've been working on this all day LOL and I would like to get to the bottom of this already.