Extension Cords

[NUSound]

Getting ready to put some cords together, and I know this topic has come up before, but I don't think we've addressed this particularly:

 

Given varying lengths (25ft, 50ft, 100ft), is there a "proper" gauge to use? Should it be assumed that a cord should be able to handle a full 20 amps from an outlet?

 

Basically, assuming I'm making 25, 50, and 100 foot cords, what cable should be used?

[oldschooler]

I like to use 12 awg SO for everything.

[NUSound]

 

I like to use 12 awg SO for everything.

 

 

That's kind of what I figured I'd end up doing, just to be on the safe side of things.

[Unalaska]

SO for outdoor, SJ ok for indoor. Generally 12ga is going to be your best friend for up to 15amps (20 if you're using the correct funky blade plugs that no one in my area has installed anywhere). Don't use 16ga (unless you know for SURE it won't see more than 8amps and it isn't a long cable), don't use orange cords since it looks really bad and unprofessional all around.

 

I like having a couple green 25ft extentions with the outlets every 8 ft. They aren't for backline (I have a 50ft stringer with quads for this), the 25 means it gets used for a lighting tree, or from the backline stringer to the front, utility purpose and it can be tapped into along it's path too. They are 14ga so no heavy current though.

[Mogwix]

 

They are 14ga so no heavy current though.

 

small lights I'm guessing.

[Craig Vecchione]

 

SO for outdoor, SJ ok for indoor.

 

 

For the sake of accuracy: NEC requires SO (called "extra hard service" in the Code) for stage use regardless of indoor or outdoor location. Short feeders on stage can be SJ.

 

As ALWAYS, what your AHJ says is what goes.

[Craig Vecchione]

Getting ready to put some cords together, and I know this topic has come up before, but I don't think we've addressed this particularly: Given varying lengths (25ft, 50ft, 100ft), is there a "proper" gauge to use? Should it be assumed that a cord should be able to handle a full 20 amps from an outlet? Basically, assuming I'm making 25, 50, and 100 foot cords, what cable should be used?

 

For 20 amps, 12AWG is acceptable for 25', 10AWG for 50' and longer. Of course, the branch circuit, outlet, cord ends and distribution if any, must also be rated for 20 amps. I've seen countless quads with 20 amp receps, and 15 amp Edison plug, into a 20 amp outlet.

[drummer_jay]

I've been in some pretty strange situations, and this reminded me of something. A few weeks ago I had a gig (drumming) in a TINY town in Nebraska. It seems we always work with the same crew EVERYWHERE in Nebraska. Their gear is hurting.. Beat to crap, monitor console is an old peavey with hardly any eq strip. Noisy, etc. They use a mackie 24 channel FOH with some knobs missing.. They get the job done, most of the time well. I can handle all that wear and tear, what I don't like is their power tap. Last gig, it was basically a breaker box on a 2x2' piece of plywood.. laying on the ground, directly behind me.

 

That's enough to make me want to seek other options next time!

[stevieb]

The short, double 3X power strips that IKEA sells seems perfect for some gear applications.

[agedhorse]

Technically SO is required, but generally (subject to the AHJ) and on non-legitimate stages, SJ will be allowed where it is used for protected application. That is applications where the cable is well protected from physical damage. This is where having a good working relationship with your AHJ is important. Cables for powered monitors is a gray area, since there does appear to be UL listed product that is technically SJ (or junior) style insulating system but carries a listing. I do not know the details but I think it's probably worth a little look-see.

 

Regarding gauge, the cable must be capable of safely handling the connected or attached load, while maintaining less than 5% total voltage drop on a continuous average basis. A 16 gauge cable may be just fine for some applications, as might be a 12 gauge. It all depends on the application, the overcurrent protection rules of the NEC do not specifically apply to anything connected to a branch 5-15/20 amp receptacle, though other rules may (like OSHA, UL, CSA, Hydro)

[NUSound]

 

Technically SO is required, but generally (subject to the AHJ) and on non-legitimate stages, SJ will be allowed where it is used for protected application. That is applications where the cable is well protected from physical damage. This is where having a good working relationship with your AHJ is important. Cables for powered monitors is a gray area, since there does appear to be UL listed product that is technically SJ (or junior) style insulating system but carries a listing. I do not know the details but I think it's probably worth a little look-see.

 

 

We do shows in 40+ *actual* theaters, so I'm guessing that we're on "legitimate" stages most of the time.

[Craig Vecchione]

Most of the outlets I run into in commercial buildings are 20 amp receptacles of this variety: Does this mean that the entire cord should be built to run 20 amps, with the male end being terminated in this configuration: Or can a 15 amp plug be used as long as everything down stream is built to 20 amp specs, the logic being that the breaker would trip before anything else downstream is damaged...? Sorry if this is confusing, but I want to make sure that this is done right.

 

If the load is no more than 15 amps, then 15 amp ends are fine. If the load is 20 amps, then everything should be rated for 20 amps.

[Craig Vecchione]

 

We do shows in 40+ *actual* theaters, so I'm guessing that we're on "legitimate" stages most of the time.

 

 

 

Yep, probably. But as I and Andy pointed out, it's the AHJ that decides what is okay and what isn't.

[Coaster]

this 15/20A thing is sometimes quite the quagmire, esp if you have the inevitable situation where your rack is setup for a 20A inlet and all that is available is a 15A duplex on a 20A breaker. i have one of my racks setup as a 15A rack because of this but i dont see how it could be within the safety margin (normal use) of a 15A breaker. i dont like it, and i dont know how to make it right except to wire it for 20A only and use a distro, which cant happen. i can only use the distro 75% of the time, the rest is 15A duplex.

 

i've been in this situation for about 6 years.

[Craig Vecchione]

 

this 15/20A thing is sometimes quite the quagmire, esp if you have the inevitable situation where your rack is setup for a 20A inlet and all that is available is a 15A duplex on a 20A breaker. i have one of my racks setup as a 15A rack because of this but i dont see how it could be within the safety margin (normal use) of a 15A breaker. i dont like it, and i dont know how to make it right except to wire it for 20A only and use a distro, which cant happen. i can only use the distro 75% of the time, the rest is 15A duplex. i've been in this situation for about 6 years.

 

 

The 20 amp circuit with 15 amp receps is a common residential situation, for example in a kitchen, where it is expected that all loads will be small appliances at 15 amps and typically much less. It really shouldn't be used in a venue, but yeah, see it all the time.

[Telecruiser]

Do not scrimp on cord plugs and receptacles. I use Leviton commercial grade on everything I do. Hubbel commercial is good too. They cost more but are damn near bullet proof. For the more critical application where an unplugged cord could shut the show down I would use twist lock connectors.

 

For the power cord I would use 12 ga. up to 50' max. and 10 ga. for 50' to 100'. SO cord is good stuff. A bit bulky to wind up and carry but it takes a lickin' and keeps on a tickin'.

[The Real MC]

NEC specs different current ratings for solid wire and stranded wire of the same awg.

 

14awg solid wire = maximum 15amp

14awg stranded wire = maximum 12amp

12awg solid wire = maximum 20 amp

12awg stranded wire = maximum 15amp

 

The reason for this is the total conductive material in a cross-section view is a lot less for stranded wire as opposed to a solid wire.

 

For stranded wire, the length of cable also affects the maximum current. This is because the ohm/ft rating varies with stranded wire gauge and is higher than solid wire. Cables longer than 25ft will need bigger awg to carry the same current.

 

The longest extension cable in my arsenal is 50ft and that doesn't get used very often. The 25ft cables are more practical. I make my own cables. Those OTS orange extension cords have caused more trouble and aren't worth a darn for gigging. They break too often. One of those cables caused an intermittent brownout during a gig and it was a devil of a time finding the culprit.

[Unalaska]

I'll agree that the orange extension cord should never see a stage (esp 16ga). On some of the cheaper rack power strips the ground plug has been coming off on them after lots of use, then I just re-attach a hubble or something similar and cool.

 

I've got a ton of 50ft and 100ft ext and 25's I've made too. They come in handy for sure! All the 14ga has been set aside in a box somewhere not to be used (xmas lights?) and the 16ga has been given away to people I know who won't use them for audio.

[agedhorse]

The only reqiurement for a true 20 amp receptacle to be installed on a 20 amp breaker is where it's the single device (not duplex) on the branch ckt.

 

15 amp rated connectors may indeed be used on a 20 amp circuit (with the provision that if the load requires 20 amps the cable be properly sized to the load.) Where the 20 amp 90 degree pole is required if for UL listing of the specific piece of equipment, it draws more than 15 amps and requires a 20 amp branch.

 

MC, re-read the ampacities of stranded wire. Somewhere you are missing something as the tables clearly indicate otherwise (for both solid and stranded wire of various types)

 

10 gauge is generally not necessary until you hit 100 feet or more. Again, the only way to know for sure is to look at the average currents and calculate the voltage drop. SO cable requires very careful terminiation so that it fits solidly into the strain relief jaws. I see a lot of improperly relieved SO out there and that WILL fail an inspection... for good reason.

[NUSound]

The only reqiurement for a true 20 amp receptacle to be installed on a 20 amp breaker is where it's the single device (not duplex) on the branch ckt. 15 amp rated connectors may indeed be used on a 20 amp circuit (with the provision that if the load requires 20 amps the cable be properly sized to the load.) Where the 20 amp 90 degree pole is required if for UL listing of the specific piece of equipment, it draws more than 15 amps and requires a 20 amp branch.

 

I feel like you and Craig are conflicting, but maybe its on semantics.

 

Anyway, is it permissible to terminate the male end of a cord with this type connector:

 

 

And the female end of the cord with this type connector:

 

 

Provided that the cable in between is rated for 20 amps.

 

Based on what you wrote, my understanding is that using the male end mentioned above, is permissible, provided that this is for an extension cord, and the connector is not being put onto a device that is listed for a 20 amp plug... sound about right?

 

Thanks in advance.

[agedhorse]

Correct.

[Craig Vecchione]

Where the 20 amp 90 degree pole is required if for UL listing of the specific piece of equipment, it draws more than 15 amps and requires a 20 amp branch.

 

And this is where I've come to that understanding. This contradicts the passage above. Color me confused. The only way it makes sense would be if it's okay to use non-listed equipment, which the code doesn't really permit...it would be analogous to restricting gun owners to non-automatic weapons if the weapons are registered, but if the weapon isn't registered it's okay to be automatic.

[agedhorse]

The primary consideration is that if a single piece is UL listed for 20 amps then it is reqiured to have a 5-20P plug.

 

The rest is again, a gray area. Commercial grade receptacles such as the 5-15R and 5-15/20R (now commonly (and incorrectly) called a 5-20R all will carry 20 amps because they are all built using exactly the same contact system. Same thing for the commercial grade plugs. Because the load is not defined, they are allowed by code to be sourced from a 20 amp branch circuit. As far as the code goes, that's where it stops... other than to say that the portable wiring must be sized for the intended load. Now the AHJ may say that in addition to sizing the wire to the load, that the plug must be sized to the load also, but since the load is not defined, and there's no listing saying what the specific load characteristics are, it's now a judgement call.

 

This is true only for the industrial and commercial style connectors with double wiping heavy spring contacts and does NOT apply to residential grade receptacles which are built differently and technically are not allowed except in residential applications which live audio is not.

[NUSound]

As always, I am most appreciative of the information.

 

It seems to me that in a case like this, education is your best friend. When the AHJ comes around, being able to let them know exactly how your system is put together, and why it is put together that way is the best course of action and should leave little room for misunderstanding.

[agedhorse]

Even if you are right, the AHJ can decide otherwise. Then you are forced with a deciaion to change or to fight. Fighting is rarely successful, though I had to fight for a customer because the AHJ did not understand how to apply the code and I won. Saved the client about $20k. Worth the effort, and the grief I received on the next job. Extra scrutiny.