# Candy Questions in Tech 6



## ship (Nov 30, 2003)

SPT-1, Lamp Cord, Nema 1-15 cord, Zip Cord, Ungrounded Extension Cords, In any terms for it, there is one side of it that's hot and one side that's neutral. Which is it?

Doesn't matter? Try unscrewing a lamp from a screw based lamp holder and getting a shock when your fingers touch the lamp's screw shell. Plug something into the cord that is polorized and it's not wired properly such as a dimmer or switch, there can be problems. It matters, there is a universal standard for the center pin of a lamp base to be the hot just as which leg on zip cord is neutral, and without the proper hot leg system, it's impossible to be sure. 

Add a Taps, and other quick connect outlets and plugs on zip cord are very common in use especially in our industry. They are non-polorized for the most part and this causes constant problems on things that are polarity dependant. At very least if you know which side of the cord goes to the neutral, you will be doing your job in ensuring they are properly powered up so the next person that uses what you set up does not get shocked. Being a lighting person means more than you can pull the shutters on a Leko and focus a beam, it also infers you know something about the craft thus the candy question and my stress on this part of it.

However as with the painting question #5, since as of this morning since only two people voted, including myself, this is my last because it still is obvious that out of 327 members, this is not something of interest to the masses.


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## wolf825 (Nov 30, 2003)

Add a Taps are prohibited in my area of the country for use and if inspected they will be tossed out.....but in spite of that they are still used and useful.


EXCELLENT question and poll by the way.....
-wolf


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## Inaki2 (Dec 4, 2003)

Whats Zip Cord?


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## DMXtools (Dec 4, 2003)

Inaki2 said:


> Whats Zip Cord?



"Unsafe" is the short reply.

It's standard two-wire lamp cord - no outer jacket. The insulation is molded around the two wires with a groove between them, so they can be "zipped" apart for termination. It's pretty common, in the US, for lamps and small home appliances. Also commonly used far speaker cable on home stereos. Not really good for industrial applications (even speaker hookups) because the lack of any outer jacket makes it pretty easy to damage. Rarely rated well for temperature or abrasion resistance.

John


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## ship (Dec 4, 2003)

See the other descriptions Otherwise All plastic parallel cord SPT-1 20-18AWG, 2 or 3 conductor, Thermoplastic, cord. It's the ungrounded extension cords most used in households for 120v wiring and most found in brown or white. You probably have something similar to it out there given different plugs. Two wires that are attached together with a thin bridge of plastic that you rip apart to wire it. One side ribbed or with two ridges, the other side rounded. Must have seen it, most table lamps and pendant fixtures come with a form of it, also a lot of cheap speaker cable uses it.


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## Inaki2 (Dec 5, 2003)

Ohhh...yeah...didn't know it was called ZipCord.....crappy little thing


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## wemeck (Dec 5, 2003)

Inaki2 said:


> Ohhh...yeah...didn't know it was called ZipCord.....crappy little thing



I think that is the Sentimental Quote of the day.


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## Inaki2 (Dec 5, 2003)

Ok so at last...which one is hot? And whats a tap???? I'm assuming no one puts water taps on light sockets....hopefully


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## wemeck (Dec 5, 2003)

Inaki2 said:


> Ok so at last...which one is hot? And whats a tap???? I'm assuming no one puts water taps on light sockets....hopefully



Taps are neat little devices that incase the zip cord or car stereo cables. They allow you to splice the lines by crimping and/or twisting the tap.


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## sparkfairy (Dec 6, 2003)

ship said:


> However as with the painting question #5, since as of this morning since only two people voted, including myself, this is my last because it still is obvious that out of 327 members, this is not something of interest to the masses.


I enjoy your questions. I'm a senior in high school and have been in tech for a long time, but I don't know all the technical names of things and have never really learned lighting and sound. So you're questions help me to learn those things. Not to mentionthat I get everyone elses opinions on the equiptment or methods in question. I just think that not many people have bothered to look over here or have not posted. I hope you keep going.


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## ship (Dec 7, 2003)

Zip cord is not authorized for stage or much industry usage but it's very frequently used in other places. Many is the time of a young person plugging a spool of it into a live socket and watching the transformer effect happen. One lighting company I once worked for that's got various locations about the US and has a name similar to winter or Jack, uses than even re-uses the stuff after the Add a Taps are removed. Used to just watch the sparking of wires to grid at the Field Museum if the ends were not taped. They would power up Lekos or hundreds of feet of X-Mass lights with it all the same no matter what the load.

I also just hot glued to my wall of shame that famous anchient zip cord I have which is very old. Bend it and the insulation just flakes off at the bend. Very nice for showing what happens to it if it's overloaded or it gets old and dry.

By the way, a Add a Tap is something that has a sharp prong that pierces the insulation of the wire so as to tap off it's power. Lamp sockets and ungrounded Edison sockets and switches frequently will do this. I stock and have sent out on shows both - they have uses and are for the most part safe to be using. Most lighting companies in the industry will stock and use them at times especially for low voltage lighting. Just not to the extent that the other company above uses them.


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## delnor (Dec 7, 2003)

Something fun to do with Zip Cord!

Do this with adult supervision only!

You need three pickles about 10 feet of zip Cord and a quick tapping edison adapter UNGROUNDED thats important.

Tap the edison plug onto one end. Cut it at about three feet and separate the ends so you have a Y shaped cable with the edison adapter on one side. Plug one end of the Y into a pickle plug the other end into the opposite end of the pickle. Now take about two more feet of zip cable and separate it, plug one piece into one end of the first pickle and into one end of another pickle, then do the same thing with the next piece of cord. Until you have about three pickles in the chain. Then turn off the lights and plug it in, and stand back! You will get a nice green light show.


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## DMXtools (Dec 7, 2003)

delnor said:


> ...plug it in, and stand back! You will get a nice green light show.


... and be cleaning up pickle shrapnel for days...

John


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## delnor (Dec 7, 2003)

Actually I have never had one explode... But it is kinda cool, the current will arch inside the pickles making a cool bright green light show of sorts.


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## ship (Dec 8, 2003)

I don't get it, did the hoist go up or down?


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## Inaki2 (Dec 8, 2003)

Good one Ship.....really good one


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## delnor (Dec 8, 2003)

Zaaaaa?


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## wemeck (Dec 9, 2003)

What's next stupid pet tricks?


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## delnor (Dec 9, 2003)

I don't know why I didnt get that before...


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## ship (Dec 10, 2003)

Let's get it up to at least 10 votes than I'll tell the answer.


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## soundman (Feb 8, 2004)

Whats zip cord ?


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## OnWithTheShow (Feb 8, 2004)

Ship,

If Zip Cord is not rated for stage use how would you wire a practical light fixture such as a table lamp or wall sconce? We often use Zip Cord and wire on a Twistlock on the end so we can just plug it into a circuit. Whats your method?


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## ship (Feb 8, 2004)

Oh' this is going to take one of my special long answers to explain. It's halfway written and will follow later unless someone else short circuits the explaining before that.

Short answer, look to the NEC for all your answers. The neutral is the ribbed side. Classifications of assembly halls or use would be the next thing to look into. A stage is I believe a class 1 or 2 assembly hall proper depending upon who runs it and how large it is. (This is all from memory.) Zip cord was already explained earlier in this posting so I will spare all of you.

After that it's on to SPT-1 or 2 wire verses lamp cord. Depends upon the fixture of course but it is only permissible to be used as a direct replacement for zip cord already on the fixture - there are heat and amperage issues otherwise in addition to use. Lamp cord without checking, while similar is not the same. When possible, for stage use all equipment should be grounded and using proper types, lengths of cable and plugs.

A sconce is designed to have a bonded ground. Unless you are using 3-conductor zip cord, you won't be grounding it which violates it's design use even with any permissible exceptions for stage applications. Also since the wiring for said wall fixture will not be seen you should be complying with the NEC for permissible wires for use on stage - not just what is cheap and easy. Otherwise why not just string zip cord all over the grid? Believe me I have seen it done and also what happens when a clamp is clamped down onto it.

For a fixture, if it is zip cord, and you are given permission for it's use by the person liable for it's use and the inspector as it might also be fine, otherwise unless used in special circumstances or specific ones that are approved, follow the code. 

Why do people love twist locks so much? 20 years ago they were the hot thing because they would not come apart and that was fealt safe. Now they have their uses but for the most part are not standard practice for just that reason. Unless you are using what would be a L1-15, L1-10 as they might be called or non-nema similar two prong plug use of a three pin twist lock plug would be a clear violation of code even if you yank the ground pin, just as you can't yank the U-ground part of a Edison receptacle. L5-15 or L5-20 plugs are grounded and you are using them on an un-grounded application and cord. That's a no no in addition to using a other than hard usage cable for the application. This is my interpitation, your person in charged might take a more leaniant stance and interpitation on such things out of necessity. Were it me, I would plug a Zip cord I needed to plug in, into a L5-15 assuming it's your plug to 5-15 adaptor, than use a polorized 1-15 plug into it. The polorized plug ensures you won't reverse hot and neutral - in other words on the screw shell of a lamp that your fingers can touch as you screw in a light bulb, it's not fed by the hot leg of power. Thus the reason for noting which part of a zip cord is hot and which is neutral also in addition to in following a standard the person that follows you hopefully won't get zapped by a accident you set up.

As for use of zip cord while working for a event company, it's common in use. As long as you don't plug in the spool and make a terrific transformer, for the most part it's safe as long as you don't overload it. The Eagle Add A Tap system is great. Just bought a hundred of each for a show using them. Expensive somewhat. They are now available in a polorized version which while larger I recommend so you can keep your fixtures safe to use if screw base. Otherwise without plugs and receptacles that are polorized - having a neutral prong larger than the hot, all the wiring the zip cord propery in the world won't help you get lamps pluged in properly. This is especially common when someone cuts off the wide flairing of the neutral prong from the fixture's plug so they can use it on a non-polorized receptacle. It's also a bad idea to attempt to re-use zip cord or not pay special attention to it's ends. I have seen sparks in the ceiling truss from it, question is since the breakers did not trip, just how old or warn out were the breakers, than what did it do to the wire? That's from exposed ends or ones that when they are cut are too close together than arc. It might just be zip cord but it's still dangerous without care. The add a tap system for the most part works well, but in piercing the jacket it does displace the wire and often damage it slightly. That damage and those holes in a wire can be dangerous to handle when the stuff is re-used with new outlets positioned without covering up the holes. One tent company tried to tell me they self seal. That would be a nope. Giving the piercing, and amperage ratings of 18/2 SPT-1, I would not put more than three amps on zip cord I was using. It's rated for up to 7 amps but would be pushing it especially once voltage drop figures in.

But lay a line of 18/2 SPT-1 along the floor, add a outlet where you have a fixture and away you go - great and fast system. Not overly safe or approved for use in all applications. Also not grounded.

There are other versions of zip cord on the market. I stock 12/3 zip cord for convention center use under carpet and with fork trucks running over it. It's also available in a actual convention center flat cable that's much similar except it does not have solid jackets over it, instead all wires are laid flat with normal insulation and a PVC jacket over them. Largest of this I have made up is a 10/5 or 6/3 version of it. Still zip cord for all intensive purposes but lots more difficult to put into a plug. Flat cable like zip cord has limited application and permissible use and is acceptable out of necessity. Some cheaper forms of office cable ramp cable also uses a three conductor zip cord with the cable ramp perminantly installed on it. 

Zip cord is not hard usage cable rated, it has a lifespan of about 20 years before the rubberized jacket becomes brittle as well as similar problems when overloaded. It's voltage rating is also not high enough for low resistance wire over a long distance at a stage lighting capacity amperage. I have a piece of zip cord mounted on my wall of shame in which all you have to do is touch it and it will expose a new section of seriously corroded wire by way of the insulation just plain falling off this cable was probably subject to higher than rated amperage and the whole length of wire went bad. Not safe at all except for low amperages and special use. Tent shows and special events have their own classificaion for what is permissible to be used. You can't be plugging a grounded piece of equipment into the zip cord iether, though it's frequently done. All it takes is one well placed spilled drink and you have a lawsuit. On stage you are not even allowed to be using SJ wire in lengths over 3' and for specified purposes. Far different than rock companies get to use it for due to the fact that truss is considered adiquate support and protection for it. Now once they lay anything other than type S such as SOOW-A wire on the ground, much less as a drop line off the or between trusses, it's possible that they are also in violation. This means that the orange zip cords are also against the rules to be used especially on stage. That's a form of SJ wire.

Have I used zip cord on stage, sure. Given it's approved for special purpose use. It's about senseless to plug in un-grounded equipment with grounded heavy duty cable. It's better given such equipment is allowed if it were plugged directly into the wall but zip cord as long as used properly can be used with approval. The NEC is a set of rules and guielines but there are common sense execptions also.


It has been necessary also to put ungrounded wire into a stage pin plug. This gets even more complex because a stage pin plug can be configured to safely run two pin cable by simply removing the ground. The problem is that unless really observant it's easy to plug it in backwards. At times like this I usually cut about 1/3 of the length of the male pin off the plug leaving a sanded to finished nub stickign out where the ground was. This confirms that the cable is not grounded as necessary I would interpite, plus helps to ensure the cable will not be plugged in backwards. On the other hand it's against the NEC because in doing so it is modifying the plug. In the case of a stage pin plug the exception of leaving the ground in place I would say is permissible and that's about the only cable for me I allow. No grounded Edison plugs or twist receptacles on circuits that are not grounded. Just one of quarks.

There it's un spell checked but done plus a bit shorter than it will have been.


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## ship (Feb 8, 2004)

oops, duplicate posting


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## OnWithTheShow (Feb 8, 2004)

Ship,

I inherited the theatre I am TD of in pretty bad shape, I am trying to figure out why things were done in certain ways I had never seen before. Wait until I post a picture of our sound racks. One day I was hanging some new fixtures in the catwalk when one of the worklights shorted out and actually started a fire on a piece of tie-line. Luckly I was there to stamp it out. I found it was a Par 56 with a 500w lamp being used as the work light and it was wired to a edison plug with zip cord. Exactly as you said a c-clamp had torn into it and shorted it out.

Guess I need to get out he NEC book and find out why a convention space is in a different category than a theatre.

Specifically how would you wire a lamp socket? Would you use a grounded cable? If you so how would you terminate the ground wire at the socket?


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## ship (Feb 10, 2004)

A 500w lamp is 4.16 amps. Given the zip cord is 18/2 it could safely run it for a year or three before I would downrate it's insulation to good for 3 amps. But 4 amps is not that huge a load unless it is continuous duty. This type of cable however is home owner grade and not acceptable for your use. Nor is it rated for lamp cord given the wattage and temperature. I'm sure if you stuck your hand into the lamp cap and bent the wire it's insulation would just flake off revealing corroded wire. How was it spliced to the lamp cap anyway wire nuts? I see this all the time. Job security.

How I would wire a lamp socket depends upon the socket. I count 139 types of lamp base currently in use with multiple designs each has for wiring to it.

In the case of a PAR 56, it uses a EMEP or GX-16D lamp base the same as a PAR 64 would. For a ground on a PAR can, it's standard that the ground wire is attached to the cap/top of the can. I'm a big fan of terminating the wire with a #10 stud ring terminal and attaching it with a actual electrical grounding screw - the green ones with the slotted hex heads that are thread forming. A washer and a stainless steel 10-32 top lock nut on the inside of the can. There is no way this screw is coming loose unless someone installed the nut backwards in which case it will strip itself.

That's as opposed to using a normal zinc screw that can rust, and a nylon lock nut (nylock) that if it gets warm enough the nylon will melt away from the screw making it just a normal no locking nut. Much less any crown nut or nut with lock washer that will not stick around to much abuse. Rivets are also suspect because they come loose. Always check your ground wire is not loose when inspecting the can. It's the difference between getting shocked and not.

As for the socket, I use my EMEP sockets made by Sylvania. Good wireing and a aluminum frame around the part that usually breaks on the socket. In other words it will survive flopping around inside the can without breaking.

One good test on all EMEP sockets is a tension test. If it will pick up a lamp than it's the proper tension. If it won't than it is trash or at least it's porcelain is spare parts. Don't try to re-tension the springyness of the PAR contacts. Yea you can do that but it won't last very long and can break especially once the current starts going thru it.

On the screws holding together the old porcelains, high temperature threadlocker works well as with replacing the nut with a real nut. Or in general when prepping the can, just take a screw driver and ensure the screws holding together the lamp base are tight. Something else you don't have to worry about on a more modern lamp base.

For wire, I use type K, (FEP) 150c in a 16AWG for the ground. It's not rated for as high of a temperature but I usually prefer my ground wires rated for less in temperature than my current carrying conductors. This way when you see a melted ground wire, it's probably also about time to swap out the other wiring too.

Lamp bases come with Type SF heat wire rated at 200c. For a PAR can that's fine. If you find that the fiberglass is wearing off a bit by the lamp base but the conductors are not exposed you can install some better quality fiberglass spegatti tubing over it or use the silicone coated fiberglass. That's one advantage the old lamp bases have in that you can put the tubing inside the lamp base. Another note about the old lamp bases is that it's often a good thing to tie the power cords coming off the lamp base into a square knot directly behind the lamp base. This will pick up a bit of the strain of the wire from the tugging and twisting that the wire otherwise is having done to it otherwise directly in the lamp base. Frequently this is the place that wears out fastest due to both heat and movement.

I'm a huge not fan of the heyco strain relief. Rubber of that slender thickness does not have a part inside an oven. Much less plastic. I prefer either a weather tight or two screw conduit strain relief. Say, am I sounding like a broken record? Could sware I have said all of this before.

Anyway, at the strain relief I use fiberglass high temperature electrical tape. This disperses the pressure on the wires and fiberglass sleeving and prevents it from cutting into the above. It also prevents the wire from bending too tightly at the strain relief another cause of it's failure.

At the plug, after the company heat shrink with clear heat shrink over it is installed on the wire, I do two layers of friction tape directly to the wire than slide the fiberglass over it. About 2" in length At work for the tech people we stop at that now. This will help to grip the fiberglass and prevent it from slipping out of the plug's strain relief and prevent the cord from bending too tight and protect the wires from that stress.

It's better if you don't cut the friction tape after you slide the fiberglass sleeve over it and instad continue wrapping the sleeving above the fiberglass with two more layers. about 1.1/2" in length. This way the fiberglass is sandwiched and cushioned inside the tape, and protected against the clamp cutting into the jacket. Most don't like friction tape use at all. "it's gummy when it's warm" "it gets dirty" "It's 2004, what are you doing using friction tape?" and many more things. In fact I'm the only one using it on plugs that I know of. To shut them up I kept the friction tape to the underside of the fiberglass only. 

Still, take a Bates plug - modern stagepin plug and install the cord and strain relief in the standard flat/rounded way, than try the friction tape with a round/round way or round/flat way depending upon the thickness. You will find with a tug that the fiberglass sleeving does not slide out of a friction taped connection but will otherwise without it. This saves money on materials and repair labor.

After all of this there is high temperature wire splicing methods that are safe and ok to be using inside a lamp cap but I think that's enough for one night. When your wire wears out but the lamp base is good contact me.


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## OnWithTheShow (Feb 10, 2004)

I was speaking of a practical fixture, like a table lamp or another usage of a type A socket. Most A sockets do not have a grounding screw.


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## ship (Feb 11, 2004)

If you are grounding the fixture than that ground goes to the frame not the lamp base at all. The idea is that if anything shorts or breaks loose, it does not create the path of least resistance that would be thru you upon touching it. Otherwise if not grounded on a medium screw lamp base (E-26 for those interested in the US, E-27 in Europe) you tend to always want to use a Nema 1-15 plug (US again) that's polorized. This way you insure that the neutral is going to the outer shell of the screw base. Now I know I'm a broken record - oops CD.

I guess it depends upon the fixture.  A little desk lamp prop on a table is probably not worth it as long as the plug is polorized and in electrically safe condition - that is unless the fixture is going to be on hour after hour in a professional setting. Plus if it's a plastic fixture, than there is not much to ground to that will be of use. Some such fixtures will have the ground even on a plastic fixture going to the conduit in the gooseneck if it's metal. But if for instance on a Ghost light that is left on 24hours a day at times, and it's expected to take a lot of abuse, than grounding it would not be a bad thing. Clip lights used during shows, them little store bought reflectors, not worth it. Etc. you get the idea. Stage lighting proper is stuff that should be grounded for sure. After that, it's a judgement call. If the fixture was once or is designed to be grounded than it needs to remain that way like for instance on a wall sconce.

Overall it's not wise to ground the screw shell of a lamp base nor attempt to ground to the frame of a cop gumball light or Mars Light as we call them. Both are the neutral. You do want to ensure both are insulated from metal or the frame or any voltage on the neutral will also be in anything you touch. The neutral while in geneal safe can carry a voltage. Treat it as a hot for safety concerns.

Fluorescent lamps also have advantages to being grounded in a different way. It helps them start in many cases.


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