Using Vampire plugs

[JerryB]

I have found several topics on cutting light strings to length and have enough electronics background to be comfortable with the concept. My question for those that have used them;

 

Do the vampire plugs have a fuse or do you just use the string without a fuse and let the fuses in the controller protect the circuit.

 

I am putting together the Holidaycoro singing tree faces and plan to cut the 100 couont strings in half to run the 50 count sections on seperate channels. I am thinking if the vampire plugs are NOT fused then I could just solder some SPT2 cord to the cut leads and hook it to the controllers screw-terminals without even needing to attach a plug which would make it even easier to custom make the light string

[bisquit476]

I would not hook directly to the controller board, if someone trips over the cord and rips out the terminal, you won't be a very happy camper. And please, don't say your setup is fool proof, cause there's always some fool to prove you wrong. Also, I've sent a PM.

[JerryB]

I would not hook directly to the controller board, if someone trips over the cord and rips out the terminal, you won't be a very happy camper. And please, don't say your setup is fool proof, cause there's always some fool to prove you wrong.

I could never say the setup is fool proof as odds are *I* would be the one to trip over the wire  LOL

 

The wiring will have stress reliefs inside the enclosure and again to the 2X4 frame that the coro board will be attached to so should be fairly robust but stuff happens.

 

If I have to I should be able to get some fuse holders from Radio Shack or someplace similar and make my own in-line fuses but with all the discussions I have seen about shortening the light strings I havent seen any mention of replaceing the fuse and have to wonder how many people just run the string without it.

[ErnieHorning]

Vampire plugs do not normally have a fuse.  There is an interest thread forming on DoItYourselfChristmas.com that appears as though it will eventually turn in to a group buy for vampire plugs that do have fuses, just like the ones on mini lights.
 

That said, the fuse is there to protect the wire in case there is an overload on the socket at the other end.  If you’re not connecting anything to the end of the string, the fuse is not needed.  If there is a short in the middle of the string, it will blow out all the lights before it, just like a normal string.

[JerryB]

AHhhh Thank you Ernie

 

I was thinking that would be the case and since there will not be anything added to the string, (each part of the prop needs its own channel,) I can just wire them in without the fuse

Edited March 8, 2013 by JerryB

[zman]

Vampire plugs do not normally have a fuse.  There is an interest thread forming on DoItYourselfChristmas.com that appears as though it will eventually turn in to a group buy for vampire plugs that do have fuses, just like the ones on mini lights.

 

That said, the fuse is there to protect the wire in case there is an overload on the socket at the other end.  If you’re not connecting anything to the end of the string, the fuse is not needed.  If there is a short in the middle of the string, it will blow out all the lights before it, just like a normal string.

Do you have a link? I tried searching for it and did not find it.

[Orville]

If you have any old light strings that don't work and the male plug is still good, but the fuses may be bad, you can use them on cut strings and just replace the fuses.   

 

I used a load of old incan and L.E.D. strings that the male plugs and female ends were still good, but the string and too many sockets were bad on, just cut off the male fused plug and soldered it to the cut string.   Just make sure you cover and insulate the wires from each other with shrink tubing or liquid electrical tape.  And I'd use the female end on strings I cut down, just in case I ever needed to add another string back to them, or if I need to just run another very short extension cord made from the male and female ends between two strands where a non-noticable gap may be required.

[DSE]

I have used these in the past

http://www.boatersland.com/anc607013.html?gclid=CIu2_KWS8LUCFShgMgod0CwA7g

[james campbell]

I would think that using those would get a bit dicey. Just because you don't overload the cord don't mean the controller is nor overloaded

[DSE]

The in line fuse were I had used a bulk spool roll.

Put 3ampers in only had one issue with shorting when one of the c-9 bulps glass had come lose and twisted the top

other than that one issue no fuse issues

 

Now that I am just about all switched to led not sure about the need?

 

But I will continue to fuse

[Max-Paul]

I feel that at times we loose our focus on some issues. MY OPINION is this and please do not feel the need to bust my chops over it. Dont agree with my opinion then you can take issues with the opinion.

 

Fuses are not there to save your light string from further damage. They are not there to keep the 20 feet of spt from melting. Fuses are there to keep your house from burning down or from starting a fire in your lawn if you happen to live south and have dry dead grass. If we lived in a perfect world, there would be fuses on each output of the controller board, not at the end of your extension cord, well really in the plug for the lights. But can you imagine the rise in cost of the controller and how much bigger the box would have to be to install the bigger board in?

 

With LED lights we need to go back and size down those main fuses in the controllers cause there are no fuses at each output. I was just giving this some thought yesterday. Was thinking besides my one blow mold that uses a 60W bulb. My next biggest current draw is the 80 C9 LEDs at just under 80w each string. I just got to go back and find out what my LED icicles draw. I am thinking that my biggest current draw on one bank might just be about 4 amps if the C9s and icicles are all on at the same time. Is there any reason that I should have bigger than 5A fuses? 15A is way over kill.

 

But as I said, fuses really are to keep your house from burning down. Any extra benefits such a minimizing damage to your display elements are just extras.

[-klb-]

I have some elements where full on for everything plugged into the controller is less than 3A. Then I freely wire to a custom connector, install 3A fuses in the controller, and remove all the fused plugs as part of the conversion.

As long as everything using that connector in my display uses the same rules, all is well. I just have to remember to put 3A fuses in if I ever swap a different board in due to any failure.

[ErnieHorning]

With LED lights we need to go back and size down those main fuses in the controllers cause there are no fuses at each output.

Those fuses aren’t there to protect your lights or the outputs of your controller either.  They’re there to protect your controller from burning down your house.  <-- A little tongue in cheek.

 

It’s a common fuse, so it’s still going to see the total current of all channels.  So to keep nuisance blowing of fuses, you’ll still need to keep it significantly high enough that you’ll still need nearly a short on a channel to blow it.

 

It’s unlikely that you’re going to see high current on multiple channels at the same time, unless you’ve overloaded the maximum current, in which case you shouldn’t have changed the fuse anyway.

[ErnieHorning]

Do you have a link? I tried searching for it and did not find it.

http://doityourselfchristmas.com/forums/showthread.php?25476-Interest-Thread-Fused-Male-Plug

 

Actual group buy will likely start soon.

[ErnieHorning]

http://doityourselfchristmas.com/forums/showthread.php?25476-Interest-Thread-Fused-Male-Plug

 

Actual group buy will likely start soon.

 

This group buy has now went live at the new thread found here: http://doityourselfchristmas.com/forums/showthread.php?25980-Fused-Male-Plug-2013-Group-Buy-Round-1

 

[ErnieHorning]

This group buy has now went live...

 

The 3 amp stackable plugs sold out in 19 hours and 35 minutes.  I expect that one of the Christmas vendors will be stocking these eventually too.

[Steven]

That said, the fuse is there to protect the wire in case there is an overload on the socket at the other end.  If you’re not connecting anything to the end of the string, the fuse is not needed.  If there is a short in the middle of the string, it will blow out all the lights before it, just like a normal string.

 

Protecting against plugging too many strings end-to-end is just one reason for the fuse.

 

The other reason is the way mini lights work. They are wired in series, but stay lit when one bulb burns out. How do they do this? There is a piece of wire coated by an oxide wrapped around the filament leads near the base. When the light burns out, the voltage across this oxide will rise to the mains voltage (120v). This will cause the oxide to break down and short out, completing the circuit and allowing the rest of the lights to remain lit. When this happens, the voltage and current through the rest of the lights will rise, which in turn will reduce their lifespan. When enough bulbs burn out, the current will rise enough to blow the fuse. If the fuse is missing, then something else will blow, which could cause a fire.

 

To prevent this from happening, keep a close watch on your mini strings and replace a bulb as soon as it burns out.

[ErnieHorning]

There is a piece of wire coated by an oxide wrapped around the filament leads near the base. When the light burns out, the voltage across this oxide will rise to the mains voltage (120v). This will cause the oxide to break down and short out, completing the circuit and allowing the rest of the lights to remain lit. When this happens, the voltage and current through the rest of the lights will rise, which in turn will reduce their lifespan. When enough bulbs burn out, the current will rise enough to blow the fuse.

 

Do you have any data to back this up or are you just quoting what you’ve heard?

 

I’ve actually tested several mini lights.  Using special power supplies, I purposely burned out the filament without damaging the shunt.  A 2.5 volt mini light can be easily burned out in one second by applying 10 volts DC to it and just enough current.  This isn’t enough voltage to damage the shunt.  By slowly increasing the voltage, I found that 54 to 115 volts was required to get an arc to short the shunt.  In reality, it’s not a short but actually 2Ω.

 

If every shunt in a 100 bulb string shorted, you would have two 100Ω resistances in parallel or 50Ω.  120 volts / 50Ω = 2.4 amps, which is not enough to overcome a 3 amp fuse.  Actually you’ll never get that far because one or more of the shunts will open first.  The shunts can only handle of about an amp.

 

The end result is that the fuse will never open because of the bulbs.