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Splice string lights?

Posted by oldalgebra (My Page) on
Tue, Jun 10, 08 at 10:00

I recently purchased three sets of globe string lights from the N---Style catalogue to hang on my patio. They are really like mini Christmas tree lights with round glass globes that independently pop over each light socket. Two wires come out from the plug, one going into the first light socket and one running the length of the light string until it terminates into the plug at the end of the string. Two wires come out from the first light socket, one going into the next light socket and one appears to run the length of the light string until it terminates in the last light socket (so that three wires run in a twisted fashion from the first light socket to the last).

My question is, can I splice the three strings together instead of plugging them end-to-end?

Can I connect the two wires that presently come out of the last light socket on the first string of lights with the two wires that presently come out of the first plug on the second string?
Or perhaps, can I cut off the last socket on the first string of lights and the first socket on the second string and connect the three wires?
Or will everything blow either way?

Thank you.


Follow-Up Postings:

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RE: Splice string lights?

No. See section 400.9.


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RE: Splice string lights?

Solarpowdered,
I don't know what Section 400.9 means. Where is it? What is it?
Oldalgebra


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RE: Splice string lights?

I think solarpowered believes that everyone has a copy of the NEC (National Electrical Code) on their desk right next to their computer. :)

I think Section 400.9 basically says that flexible cords have to be continuous. No splices.


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RE: Splice string lights?

OK. So the important people who wrote the National Electrical Code wouldn't want electricians splicing flexible cords. But, let's say, one was having a party, wanted to string the above mentioned lights in a continuous line, and didn't intend to leave them up overnight, would either of the examples produce positive results? Theoretically speaking, of course.


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RE: Splice string lights?

"I think solarpowered believes that everyone has a copy of the NEC (National Electrical Code) on their desk right next to their computer. :)"

Close. SolarPowered believes that it is extremely foolish to fool around with electrical wiring without a copy of the Code. When properly applied, we have been able to make electrical power very safe. When improperly applied, it is extremely dangerous. Many, many people have died to bring you the collective wisdom embodied the the NEC. The rules are there for a reason--and usually that reason is that someone (typically many someones) did things differently, and they or someone else died as a result.


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Next post...

"OK. So the important people who wrote the National Electrical Code wouldn't want electricians splicing flexible cords. But, let's say, one was having a party, wanted to string the above mentioned lights in a continuous line, and didn't intend to leave them up overnight, would either of the examples produce positive results? Theoretically speaking, of course."

Is there a problem with connecting them end-to-end, as they are designed to be used, and have been extensively tested by UL to be safe in that configuration?


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Arc Flash

A case in point:

Here is a link that might be useful: Arc Flash Video


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RE: Splice string lights?

String lights usually have a pair of fuses hidden in the male cord cap ........Just plug them in end to end........


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RE: Splice string lights?

OK. I'm back. I didn't splice the light strings. Instead, I am thinking of purchasing a 100 foot string of lights, but only need 68 feet. Can I cut the rest off? They sell the cords in 50 foot lengths, but that will be too short.

Below is the cord I am thinking of purchasing.

Here is a link that might be useful: C7 100 Foot Cord


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RE: Splice string lights?

Umm, I don't think so. Did you just receive a wirecutter as a gift you want to try out? ;-)

Seriously, I would say no. This stuff is not glad wrap, just unroll what you need etc...those bulbs are probably connected in series (correct me if I'm wrong) and they are not each rated at 120v but rather less, so when they are all run together as they should, they 'share' the voltage between them and none get fried. If you shorten the wire (and what would you put on the end?) you are reducing the load, and the lights would not last and might even pop, just like that video or the bridge of the Enterprise, or Voyager or any other star trek bridge....

Don't cut them. Double it back, or run it around the corner or something...and something makes me wonder if this is a party that will be round a pool? If so, you have to be extra careful about electrial safety and strung-up lights, lest they fall in the water.


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RE: Splice string lights?

In this case they aren't series connected so you could cut the
string flush with the last light and seal the cut with silicone rubber
sealant. Let it dry overnight before you string the lights. While
not code compliant it will be safe enough for temporary use.


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Not code Compliant

I should have said UL compliant since NEC doesn't cover
this type of device.


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RE: Splice string lights?

OK. Now I can use my brand new, handy dandy, super duper wire cutter I got for my birthday. Yipeeee!

Not really.

We do not have a pool, but I will be extra careful, none-the-less.
One more question: What does "series connected" mean? Does it mean if one goes out the rest stay on?


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RE: Splice string lights?

LOL re the wire cutters. Series connected means they're daisy chained and one goes out, they all go out. Maybe these aren't what you're looking at but I would not adopt saltcedar's method by any means, silicone is not an adequate way of sealing an end although it would be mostly waterproof. If those strings were cuttable you would need to terminate them more suitably but I would recommend not cutting it at all.


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RE: Splice string lights?

Just the opposite. Series connected means one goes out, they all go out. Here's a series circuit...

PLUG -)---O---O---O---O---O---O---O---O---O---O---O---O---!
PLUG -)---------------------------------------------------------------!

The dashes and vertical lines represent wire. The Os are the lights. Electricity needs a complete path to flow. That's why there are two plug blades and two wires coming out the back of the plug. Imagine the two wires and lights as a continuous loop.

If one of the lights burns out, the loop is broken. The flow of electricity stops, killing all the lights. It's like a breakdown on a one-lane road. All cars on that road go nowhere.

Here's what a parallel-conneced circuit looks like...

! PLUG !
!---O---!
!---O---!
!---O---!
!---O---!
!---O---!
!---O---!

A parallel circuit looks like a ladder. Each light (the ladder rung) is connected across the voltage source. Imagine that each lamp has it's own loop to complete the circuit. If one light burns out the others remain lit as those loops are intact. It's like a breakdown on a freeway - except with lanes separated by Jersey barriers. Traffic in that lane stops while the clear lanes keep moving.

Yeah...the graphics are awful. I hope this helps.

Peace.

Marco


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RE: Splice string lights?

Your lights are series connected. They look like the series diagram Marco posted above, plus another wire running from the first light to the receptacle on the other end so that there is power (hot and neutral wires) for the next string to plug in to.

So if you cut them short they will not work, and if you try to splice the appropriate wires at the cut there will be too much voltage per lamp and shorten their life dramatically (Maybe not long enough for the party).

I don't understand the objection to the plug and receptacle between strings of lights. They aren't terribly big and can have a ribbon bow or something to hide them.


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RE: Splice string lights?

OK, you guys. I'll just plug them end to end.

I don't understand the objection to the plug and receptacle between strings of lights. They aren't terribly big and can have a ribbon bow or something to hide them.

It's a woman thing.

Thanks everyone for all your input.
Denise C. - aka oldalgebra


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RE: Splice string lights?

The string that she linked to uses C7 light bulbs. Aren't they 120V bulbs? Therefore wouldn't they be linked in parallel, not series?


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RE: Splice string lights?

Yeah, they didn't check the link to see that.
The string can be shortened to any length.


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RE: Splice string lights?

The strings she has are wired series, by the description she gave of 3 wires running the length.

The 100 ft string she was thinking about buying is wired parallel. Yes, it would work if shortened, legality questionable.


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RE: Splice string lights?

those c7 lights are wired in paralell and use 3-10 watts a piece. you can successfully terminate them by wsing a spt-1 female zip connector. you can buy them at christmas lights etc.com. It's probably too late, though. :(


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