Control/Dimming Dimmer Soca with one non-dim circuit

[Marshall Gwyn]

I have small show I am running only 1 soca and 1 DMX to the DS FOH wash truss.

Dimmer is a CD-80 with 12 - 20amp circuits. Soca is 12/14.

5 channels will be for conventionals and 1 will be for powering 2 LED Blinders via DMX/Non-DIM AC.

My questions:

1: Can I take one of the channels from soca and safely plug it into like a courtesy 110v outlet, while the other channels are on dimmer power? On 12/14 the ground wires are shared, so as long as I keep the 110 non dim channel on the same ground I should be fine I imagine.

2: How terrible is it if I set the CD-80 on one channel to just be non-dim and put it on a square curve? I know this is sometimes frowned upon but wonder if a situations this minor would be acceptable. I know its my gear it could damage.

3: While searching other threads, I read that someone said soca connections are only rated for 10amps even if on 12ga cable? I've never heard this but don't really believe it considering the dimmer has 20amp breakers and soca connections.

 

[MNicolai]

1) Yes, but...

2) You shouldn't. Some power supplies for those types of devices will work, or at least work for some period of time. Most are not designed for being run through dimming circuitry even if its parked at full, and you risk blowing the power supplies up. It's your risk to take, but unless your LED fixtures specifically say they can be run off of a parked dimmer, I would find your non-dim power elsewhere.

This is an area where it may work fine for 10 minutes or 10 weeks before a problem develops.

Probably not going to happen with an LED fixture, but if you had an arc-source fixture and you tried to strike the lamp on a conventional dimmer, you may kill the dimming electronics with the inrush current required to strike that arc.

3) The issue isn't wire gauge or OCPD (OverCurrent Protection Device -- circuit breakers, fuses, such not). It's thermal dissipation.

Because you have 6 circuits worth of wires bundled together in a single jacket, if you run them all at 20A each at the same time for long enough, they will scorch their insulation and begin to melt the cable because they collectively heat the cable up.

With "Electrical Diversity", it is assumed you will usually not use your circuits maxed to 20A, or if you do, that you will not be using all 6 simultaneously. This is a bigger issue with sustained loads than it is instantaneous. Setting off an Atomic Strobe will draw a lot of current but for such a brief period of time that it does not overheat the cable. Whereas putting 3 Source Fours together on a circuit is more likely to be a sustained load that will heat the cable much more effectively because it's likely to be left on for a longer stretch of time.

General rule of thumb for any bundling of power cables. Anytime you stick a bunch of them together, you have to derate their capacity to use them all at once and/or accept that you cannot use them all together at the same time. This applies to multicable as well as big bundles of copper wiring in the wall or a grouping of multiple power cables run together on the floor. Physics is physics.

 

[RonHebbard]

I have small show I am running only 1 soca and 1 DMX to the DS FOH wash truss.

Dimmer is a CD-80 with 12 - 20amp circuits. Soca is 12/14.

5 channels will be for conventionals and 1 will be for powering 2 LED Blinders via DMX/Non-DIM AC.

My questions:

1: Can I take one of the channels from soca and safely plug it into like a courtesy 110v outlet, while the other channels are on dimmer power? On 12/14 the ground wires are shared, so as long as I keep the 110 non dim channel on the same ground I should be fine I imagine.

2: How terrible is it if I set the CD-80 on one channel to just be non-dim and put it on a square curve? I know this is sometimes frowned upon but wonder if a situations this minor would be acceptable. I know its my gear it could damage.

3: While searching other threads, I read that someone said soca connections are only rated for 10amps even if on 12ga cable? I've never heard this but don't really believe it considering the dimmer has 20amp breakers and soca connections.

Hello!
As no one else has gotten to you yet, let me jump in. Referring to your numbering;
1. Sure. Soca break in, with or without adapters, one circuit fed from a regular, non-dimmed, wall receptacle and the remaining five fed from 5 dimmers of your existing Strand CD80 pack. Effectively giving you one circuit at whatever the wall receptacle is good for, typically 15 Amps at nominally 120 Volts at 60 CPS or Hertz if you prefer.
2. In a word: NO! DON'T DO IT!! You're correct. The Strand pack won't care, and won't be harmed, but don't chance this with your, or anybody else's, gear.
3. I've never heard this either. I wouldn't make a policy of making and breaking Soca's under load but as far a mating them and un-mating un-powered and loading them up to 20 Amps at 120 Volts at 60 Hertz you have my permission to do so 'till the cows come home, whatever my permission's worth.
Take care.
Toodleoo!
Ron Hebbard.

 

[JD]

As said in more text:
Courtesy outlet is fine, but don't use a dimmer parked at 100%

As for "Diversity", any one circuit would work fine at 20 amps. However, running all 6 at 20 amps (fully loaded, lights on full) would be a problem due to cable heat.
We're not talking about the occasional "full wash" but more an extended event where heat can build up.
Soca is often used for distribution running off six 20 amp breakers. But, this requires a bit of common sense. You wouldn't use them at a carnival to run six electric grills that each draw 20 amps all day unless you wanted to turn the cable into a 7th.

 

[STEVETERRY]

I have small show I am running only 1 soca and 1 DMX to the DS FOH wash truss.

Dimmer is a CD-80 with 12 - 20amp circuits. Soca is 12/14.

5 channels will be for conventionals and 1 will be for powering 2 LED Blinders via DMX/Non-DIM AC.

My questions:

1: Can I take one of the channels from soca and safely plug it into like a courtesy 110v outlet, while the other channels are on dimmer power? On 12/14 the ground wires are shared, so as long as I keep the 110 non dim channel on the same ground I should be fine I imagine.

2: How terrible is it if I set the CD-80 on one channel to just be non-dim and put it on a square curve? I know this is sometimes frowned upon but wonder if a situations this minor would be acceptable. I know its my gear it could damage.

3: While searching other threads, I read that someone said soca connections are only rated for 10amps even if on 12ga cable? I've never heard this but don't really believe it considering the dimmer has 20amp breakers and soca connections.

The loading of 6-circuit multicables is normally subject to 50% diversity as dictated by NEC tablle 520.44(C) (3).

Please see this article for a full discussion of electrical diversity.

http://www.etcconnect.com/uploadedF...Understanding_Hidden_Electrical_Diversity.pdf

ST

 

[danTt]

Hello!
As no one else has gotten to you yet, let me jump in. Referring to your numbering;
1. Sure. Soca break in, with or without adapters, one circuit fed from a regular, non-dimmed, wall receptacle and the remaining five fed from 5 dimmers of your existing Strand CD80 pack. Effectively giving you one circuit at whatever the wall receptacle is good for, typically 15 Amps at nominally 120 Volts at 60 CPS or Hertz if you prefer.
2. In a word: NO! DON'T DO IT!! You're correct. The Strand pack won't care, and won't be harmed, but don't chance this with your, or anybody else's, gear.
3. I've never heard this either. I wouldn't make a policy of making and breaking Soca's under load but as far a mating them and un-mating un-powered and loading them up to 20 Amps at 120 Volts at 60 Hertz you have my permission to do so 'till the cows come home, whatever my permission's worth.
Take care.
Toodleoo!
Ron Hebbard.

Here's a few followup/related questions I'd love the brain trust to weigh in on..

1) Five circuits of Dim @ 120v, 1 circuit of 208? Kosher assuming appropriate connectors?
2) If the venue had an separate "sound ground" setup, can those circuits be used in a 12/14 (shared ground) multi? Or would you be bonding the building grounds in a not very nice way...

 

[RonHebbard]

Here's a few followup/related questions I'd love the brain trust to weigh in on..

1) Five circuits of Dim @ 120v, 1 circuit of 208? Kosher assuming appropriate connectors?
2) If the venue had an separate "sound ground" setup, can those circuits be used in a 12/14 (shared ground) multi? Or would you be bonding the building grounds in a not very nice way...

If I had a brain I wouldn't wade into this one but apparently I don't so here goes.
You're in the U.S. and, officially, subject to different codes and rules than I am in Canada but, that said, were still living in the same world with the same laws of physics.
One major factor is the temperature rating of any conductor's insulation.
Another is the physicality of the various situations.
For example, there are huge differences in approved / acceptable ratings for individual conductors separated in "free air" compared to jammed in conduit and/or within a common over-all jacket. And then there's length of run(s) including both the hot and neutral / feed and return & current carrying or not.
Having hinted at all of the above concerns, let me comment upon your specific queries;
1) Assuming all of the above have been taken into consideration, proper connectors properly installed can work for me.
2) In reality there can only be one ground within a typical venue and, as I understand it, everyone's ground has to reference from that one point. (Often a bus bar running around the walls of the venue's main substation.)
Some large venues, stadiums encompassing several city blocks, have multiple services feeding four, or more, main substations. I understand they all adhere to the 'one ground' rule. Many, many actual rods but all, eventually, electrically connected. I also believe when film shoots bring generator trucks to provide additional Ampacity they are required to bond to the same common ground and not simply the nearest sign post sunk in dry soil.
Realistically, and more to your point, the sound folks don't mind being on your ground but they want to have their own, sound only, path as directly as possible to the main ground without having to share conductors carrying your loads. They're often quite happy when their grounds are electrically their own with as low an impedance as attainable to where the common point of their 'wye' transformer's secondary bonds to the common ground.
In the sense of your question: No! Folks wouldn't be pleased with you.
O.K. Asbestos undies securely in place. Let my public flogging and stoning begin!
Edit: Removed an inadvertent / redundant "the".
Toodleoo!
Ron Hebbard.

 

[Marshall Gwyn]

Guys these are all fantastic answers. Thank you! Enjoyed the knowledge of the 50% diversity loading. And of course pulling a full 120 Amps thru soca seems pretty sketchy to me so I've never pushed them quite like that!

How about 6/4 power distribution cabling? We use it often. With temp power boxes. Is this subject to the 50% diversity principle?

 

[MNicolai]

2) Even if you're on an isolated ground system, you're already bonding all of your endpoint devices on that branch back to a big honkin' lowest-practical-impedance conductor back to an central isolated grounding point at your iso transformer. You see this in touring amp racks all the time. They are fed by a 30A or 32A HHHNG cable and use a power distro inside of the rack distribute that to the amps accordingly, all sharing one isolated ground conductor back to another distro. Most important thing is where that feed cable comes from. Preferably a company switch on the isolated ground system.

In terms of distributing AC out to powered speaker arrays, I've seen 18-conductor requested for this but I question its purpose. If you're bonded between circuits at the power distro rack, it doesn't much matter if you're also bonded between circuits within the cables. Again -- comparing to an installed isolated ground system -- you may have a dozen amplifiers in an equipment rack all fed by individual orange receptacles, each with their own isolated ground conductor to them. All of those amplifiers are still also bonded together on the rack rails. Sometimes you'll see a single large conductor brought into the rack that all of these receptacles bond to on a buss bar, sometimes its a home run for each receptacle back to a branch panel. Either way, they still bond together in a localized manner, referenced to same ground voltage level.

What really irks me is when I see multicable used for driving NL4's or NL8's out to speakers. The pairs within a multicore cable aren't twisted. If you have 150' from your amps to your speakers, you now have 150' of cable susceptible to crosstalk between the pairs and from adjacent noise sources. I've listened to the Left array of system come out of the speakers in the Right array -30dB down because of untwisted wires that were run along side each other in tight pack. Use something with pairs that are individually twisted.

 

[RonHebbard]

Guys these are all fantastic answers. Thank you! Enjoyed the knowledge of the 50% diversity loading. And of course pulling a full 120 Amps thru soca seems pretty sketchy to me so I've never pushed them quite like that!

How about 6/4 power distribution cabling? We use it often. With temp power boxes. Is this subject to the 50% diversity principle?

Speaking for myself, I'd want more detailed info'.
When I read your 6/4, I'm interpreting it as 6 gauge / 4 conductors within a common over-all jacket.
Tell me more:
Copper or aluminum conductors?
What type of insulation rated at what operating temperature?
Are the four conductors three, 3 phase, legs, no neutral plus one ground powering a Delta load?
Are the four conductors 1 hot, 1 neutral, 1 normal ground and 1 iso-ground?
Are you breaking all legal conventions and running 2 hots with 2 neutrals and NO Grounds???
I trust you see what I'm asking.
If you give us more detailed info', many of us will gladly give you our opinions.
Tag! You're it!!
Toodleoo!
Ron Hebbard.

 

[JD]

The derating has to do with how many current carrying conductors are in the same sheath. The second factor has to do with the temperature rating of the cable.
If your 6/4 is HHNG then you have 3 current carrying conductors. On your 12/14 soca, you have 12 current carrying conductors.
A cable rated at 60 degrees has less capacity than a 90 degree cable. And of course, open air single conductors have a higher capacity than those in a conduit.
Lastly, there is diversity as listed by the NEC, which factors in what you could expect in a real-world theater setting. Without factoring in diversity, electrical , the cable would have a horrendous derating.

 

[Marshall Gwyn]

Mike - So use Cat6 for juicing the arrays since it's twisted pair? JK!

Ron - Not sure on all the exacts but it's your standard California style twistlock w/ 2 hots, 1 n, and 1 g. Likely SOOW.

John - Thanks!

 

[BillConnerFASTC]

I would not mix 208 with 120 in the same connector. Errors resulting in damage or injury are simply too easy to make relying only on pin out.

 

[derekleffew]

3: While searching other threads, I read that someone said soca connections are only rated for 10amps even if on 12ga cable?

Can you point us to this citation so that it may be corrected? I'm hoping you misread or misunderstood it.

Was it this?

There are 12 current-carrying conductors in a 6-circuit soca. Derating is 50%, starting with 20A (from 400.5(A) column A, giving a 10A maximum. Three 575W loads will pull 15A (at 115V) or 14.37A (at 120V), so either is over the rating. I don't see how any of the 310.15 exemptions apply as the different circuits aren't coordinated.
/mike

Many terms come into play with an assembled cable: diversity, electrical; voltage drop; derating. But one random Socapex SL419-style connector http://whirlwindusa.com/catalog/bul...s/19-pin-socapex-standard-multipin-connectors lists

Solder-style goldplated contacts are rated at 23 Amps and accept 12 or 14 Gauge wire.

 

[JD]

The way I read the derate is that figuring 100% of six 20 amp circuits would be 120 amps. 50% would be 60 amps. BUT look at the whole capacity of the cable.
So, any given circuit could have 20 amps on it, but the total of all six circuits should not exceed 60 amps. So yes, you could have six 10 amp loads, or three 20 amp loads with the other 3 not in use, or 20+5+10+15+5+5 etc.
I would also agree that mixing voltages on a single soca is a BAD thing.

 

[BillConnerFASTC]

The way I read the derate is that figuring 100% of six 20 amp circuits would be 120 amps. 50% would be 60 amps. BUT look at the whole capacity of the cable.
So, any given circuit could have 20 amps on it, but the total of all six circuits should not exceed 60 amps. So yes, you could have six 10 amp loads, or three 20 amp loads with the other 3 not in use, or 20+5+10+15+5+5 etc.
I would also agree that mixing voltages on a single soca is a BAD thing.

I agree with your take on the basis for 10 amp per circuit - average.

And yeah - I can only see a bad moon rising making one pair of contacts in a socapex 208. Just begging for an unscripted show.

 

[Marshall Gwyn]

Can you point us to this citation so that it may be corrected? I'm hoping you misread or misunderstood it.

Was it this?
Many terms come into play with an assembled cable: diversity, electrical; voltage drop; derating. But one random Socapex SL419-style connector http://whirlwindusa.com/catalog/bul...s/19-pin-socapex-standard-multipin-connectors lists

It was mentioned here, but was written from someone in the UK with different voltage so that could be the communication issue. Another goes on to correct that amphenol brand is rated for 25amps.

http://www.blue-room.org.uk/index.php?showtopic=62206

 

[BillConnerFASTC]

The amphenol site says available up to 25 amps. Not sure all are and not sure what applies in US. Lex says 20 amps per circuit based on the 50% diversity, which suggest their listing is for 10 amps average across the 6 circuits. I really don't know about codes outside of US.

 

[RonHebbard]

I would not mix 208 with 120 in the same connector. Errors resulting in damage or injury are simply too easy to make relying only on pin out.

Appreciating your concerns but when you're patching 6 circuits from a 120/208 volt three phase supplied pack or rack, are you not in reality already effectively doing this so far as within your 'pin to pin' wired Socapex connector is concerned?
Once you've brought your connections out to correctly chosen and wired male connectors on a Soca "break in" and done similar with correctly chosen and wired female connectors at the other end (which have been successfully bench tested as a mated pair) are you not then good to go with only 'pin to pin' straight Socapex male to female extension lengths inserted in between your already tested and correctly wired adapters? Do you feel this is putting too much faith in your wired and pre-tested 'break ins' and 'break outs'?
I don't believe for a moment that anyone's suggesting shuffling contacts within Socapex connector shells here but I suppose I could be wrong. It's not like I haven't been known to be misinterpreting postings before.
Whip me! Beat me!! Make me write bad cheques!!! With asbestos undies securely in place.
Toodleoo!
Ron Hebbard.

 

[BillConnerFASTC]

With custom break-ins and break-outs, it will work, until someone mixes up custom break-ins and break-outs with standard.