Control/Dimming Wire Woes/CD80 pack

[Lotos]

JD is right. Let's do some math here:

12 x 20A dimmers = 240A total

4 x 20A = total load per each of the three neutral conductors

Assume best case that three of the four dimmers are on different phases. In that case 20A (max imbalance load) x 1.30 (non linear load ampacity adjustment)=26A

Now add the fourth dimmer, which is a straight imbalance: 26A + 20A =46A

Now, it is entirely possible that a #10AWG 125C conductor could handle 46A to UL's satisfaction. Here's the problem: the outlet terminations are rated at 60C, and they are used as part of the daisy chain.

75C per HUBBELL HBL2310 AC Receptacle NEMA L5-20 Female Black 125 Volt 20 Amp - Our Item #: 5879, Category: Receptacles / Wall Plate : StayOnline.com... But you're right, that's far less than 125C (Probably why I'm replacing connectors with some nasty damage...)

[edit to remove idiocy]*see post further on*

While the CD-80 pack is a venerable example of portable dimming, this neutral daisy chaining is an extremely marginal design, and one that can be easily improved by wiring a single neutral conductor to each pair of outlets on a dimmer, as long as you're in there tearing out burned wires and outlets. After all, there's a reason they burned, and I don't buy the male plugs as the culprit.

Based on the damage I saw, I don't see anything else possible as the culprit... The neutral's further down the line are fine. The damage was isolated locally to the damaged connectors.


Please, don't misread disrespect into these posts If I'm being completely braindead, let me know!

 

[mrb]

i think that pack was rewired by someone at some point. Perhaps someone changed the output panel. There should be more than three neutrals. The pack can be switched from three phase to single phase by moving the blue anderson connector (and by moving a switch on the control board). circuits 5-8 are on the B phase in 3ph operation, in 1ph operation 5-6 are on A phase and 7-8 are on C phase. As such 5-8 need more neutrals.

 

[Lotos]

i think that pack was rewired by someone at some point. Perhaps someone changed the output panel. There should be more than three neutrals. The pack can be switched from three phase to single phase by moving the blue anderson connector (and by moving a switch on the control board). circuits 5-8 are on the B phase in 3ph operation, in 1ph operation 5-6 are on A phase and 7-8 are on C phase. As such 5-8 need more neutrals.

You're right, of course...
1-4 are Phase A, 5-8 Phase B, 9-12 Phase C...
I need to engage brain before typing, and shouldn't reply to work threads at home unless I do so.

This pack is wired factory default for Twistlock (Stage-Pin packs are a totally different creature)... Neutral Bus is then wired thusly:
1, 4, 7, 10 Neutral 1 (Two Phase A's, 1 B, 1 C)
2, 5, 8, 11 Neutral 2 (1 Phase A, 2 B's, 1 C)
3, 6, 9, 12 Neutral 3 (1 Phase A, 1 B, 2 C's) (This is of course ignoring the 'Test Circuit/Hot Pocket', which is also drawing it's power from Phase C, but bypassing the SSR)

Thus, I've got egg on my face, and SteveTerry and JD's math is impecable.

 

[jstandfast]

Point taken. For me, the trainwreck is the marginal design of the neutral conductors.

ST

It's my good fortune that many moons have passed since I was inside a CD-80 pack, but I do seem to remember more white wires coming off the load side of that barrier block......

 

[Lotos]

It's my good fortune that many moons have passed since I was inside a CD-80 pack, but I do seem to remember more white wires coming off the load side of that barrier block......

I will remind everyone that this is a L5-20 Twistlock CD-80 Pack...

The front panel layout, and neutral runs are a horse of a different colour than when compared to a 2P&G Stagepin Pack, or a Socapex output pack. (I have no clue what the U-Ground front panel looks like, or the various 'combo' panel designs)
(3 rows of 8x L5-20, vs 2 rows of 12x 2P&G, vs 2 rows of 2x 6-Circuit Socapex)
I have the 'big three' sitting around here, and they're all slated to get opened... I'll be sure to snap off pictures to outline the differences.

 

[journeymanjohn]

Not to hi-jack the thread, but when refering to NOT using SO inside the pack, I have seen several CD80 packs with socapex tails installed as outputs. Of course, these have a seperate neutral for each circuit that land on a terminal strip, bit still the temp inside the pack is something to be considered. Would these be considered unsafe??

 

[mrb]

Not to hi-jack the thread, but when refering to NOT using SO inside the pack, I have seen several CD80 packs with socapex tails installed as outputs. Of course, these have a seperate neutral for each circuit that land on a terminal strip, bit still the temp inside the pack is something to be considered. Would these be considered unsafe??

Is that a manufacturer supplied option, or something someone cobbled together? If its the latter, I would have to say its not kosher.

As far as the socapex tails, while there is some SOOW socapex cable out there most socapex cable is AWM 2586 which has UL 1015 inner conductors which is a 105deg C 600v pvc insulated conductor. Probably not up to par for the heat it could encounter in a dimmer pack. Most internal dimmer wiring is XLPE or FEP.

 

[Lotos]

Not to hi-jack the thread, but when refering to NOT using SO inside the pack, I have seen several CD80 packs with socapex tails installed as outputs. Of course, these have a seperate neutral for each circuit that land on a terminal strip, bit still the temp inside the pack is something to be considered. Would these be considered unsafe??

CD-80's did come from the factory in multiple Soca configs.
They would have had the soca connectors on the output panel of the pack, for you to hook up a splay to, and/or connect straight into a soca run.
The interior wiring, AFAIK, is still XLPE.

 

[JD]

still the temp inside the pack is something to be considered. Would these be considered unsafe??

If your dimmer pack is getting anywhere near 105c inside, it may be the least of your worries

High temp wire is called for either because the wire may come in contact with something hot (Such as in a fixture), it may become hot itself, or due to density, heat may develop. You will often find very low temperature wire in a dimmer pack on the control circuits and low voltage components.

High temp wiring also may be used due to characteristics outside of just temperature and current, such as flame resistance. This is why you should always look for exact replacement.

As for pack temperatures, dimmer packs should never be more than "warm" to the touch.

 

[derekleffew]

... I have seen several CD80 packs with socapex tails installed as outputs. ...

Just to be clear, are we talking about
1) a panel-mount 19-pin connector, or
2) a length of 12/18 or 12/14 cable through a hole in the pack's output panel (hopefully with appropriate gland and strain-relief) with a cable-mount female Socapex-style connector on the end?

 

[journeymanjohn]

Sorry it took so long to get back to this. Wiring up a refinery outa town, and the laptop crashed.

These would be the soca tails hanging through the holes. Whether or not they had strain relief kellum grips, I cannot say. I see em advertised on various websites for used gear. It's how I am planning on wiring my CD80 pack.

We are buying alot of wire on this refinery project (good prices), and the purchasing agent has agreed to order it for me and I'll get it at their cost.

 

[jstandfast]

Sorry it took so long to get back to this. Wiring up a refinery outa town, and the laptop crashed.

These would be the soca tails hanging through the holes. Whether or not they had strain relief kellum grips, I cannot say. I see em advertised on various websites for used gear. It's how I am planning on wiring my CD80 pack.

We are buying alot of wire on this refinery project (good prices), and the purchasing agent has agreed to order it for me and I'll get it at their cost.

Without regard to their availability online, or however those 19 pin tails are strain reliefed exiting the pack; the notion itself is best referenced by paraphrasing a quote from a famous former American President (now deceased) : " You could do that, but it would be wrong ".

 

[Lotos]

Without regard to their availability online, or however those 19 pin tails are strain reliefed exiting the pack; the notion itself is best referenced by paraphrasing a quote from a famous former American President (now deceased) : " You could do that, but it would be wrong ".

+1 to that.

The CD-80 we have that is soca-wired from the factory, is done so using 4x female panel-mount 19-pin connectors.
Wiring it in any other fashion wouldn't be kosher, at least not to me.

 

[journeymanjohn]

Well, I'm still gonna give it a go. Gonna install 4 tails, kellum grip connectors, 12 gauge 14 conductor SOOW. Having a local machine shop fab a rear panel to match the existing.... holes relocated of course. I could have it fabbed for 19pin female panel mount, but frankly.... I am more comfortable with cleanly routed and shaped individual conductors vs the space required for the flush panelmount 19 pin receptacles. Each circuit will have it's individual neutral to the busbar (unlike what I see in the OPs photo). Safer from what I believe. Quality 3M stickyback tie wrap bases, properly bundled and labeled conductors. 24 15amp breakers.

Of course I terminate panels for a living, and the pack will be inspected regularly.

 

[Chris15]

Well, I'm still gonna give it a go. Gonna install 4 tails, kellum grip connectors, 12 gauge 14 conductor SOOW. Having a local machine shop fab a rear panel to match the existing.... holes relocated of course. I could have it fabbed for 19pin female panel mount, but frankly.... I am more comfortable with cleanly routed and shaped individual conductors vs the space required for the flush panelmount 19 pin receptacles. Each circuit will have it's individual neutral to the busbar (unlike what I see in the OPs photo). Safer from what I believe. Quality 3M stickyback tie wrap bases, properly bundled and labeled conductors. 24 15amp breakers.

Of course I terminate panels for a living, and the pack will be inspected regularly.

I thought we'd worked out that the temperature rating of SOOW etc was not suitable for the innards of a dimmer rack and that XLPE was more suitable. And I'd NEVER take a cable mounted connector over a panel connector... Where does a cable fail 95% of the time? Just after it leaves the strain relief... If you can mechanically support the connector that will considerably lessen the likelihood of failure associated with that connector. Plus it makes it easier to mate since the connector can't spin while your'e connecting it.

 

[JD]

Short runs of multi-cable should be avoided at all cost! On a long cable, the conductors slowly rotate around the core which gives them some "give" for flexing. On short cables there is not enough length for rotation and most of the strain ends up being carried by only a few conductors.

 

[mrb]

Well, I'm still gonna give it a go. Gonna install 4 tails, kellum grip connectors, 12 gauge 14 conductor SOOW. Having a local machine shop fab a rear panel to match the existing.... holes relocated of course. I could have it fabbed for 19pin female panel mount, but frankly.... I am more comfortable with cleanly routed and shaped individual conductors vs the space required for the flush panelmount 19 pin receptacles. Each circuit will have it's individual neutral to the busbar (unlike what I see in the OPs photo). Safer from what I believe. Quality 3M stickyback tie wrap bases, properly bundled and labeled conductors. 24 15amp breakers.

Of course I terminate panels for a living, and the pack will be inspected regularly.

i dont see why you would install tails over panel mount connectors. The panel mount soco connectors require less depth out the back of the panel than the twistlocks and stagepins that are common on these dimmers.

whats with the 24 15 amp breakers?

 

[derekleffew]

...whats with the 24 15 amp breakers?

See this thread: http://www.controlbooth.com/forums/lighting-electrics/16394-cd80-questions.html .

 

[journeymanjohn]

Well, I like the idea of tails, if for nothing else but the cramped stages and easy access. I can see this either on top of, or God forbid... behind a piano, stashed in a corner.

I don't expect to be pulling any extreme amperages, quite mild ones actually, and don't expect extreme heat.

I'll take some temp readings while designing and programing in my garage though.

One thing I am considering though, as I have seven 5 (6") foot triangle truss assemblies, is not going with the 19 pin connector. BUT I am unsure of what other connections would be acceptable / available. Would be nice to load in, plug a connector to each pre wired truss, and be done with it. Maybe better to use break-ins and outs for that??