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[James Feenstra]

Alan Hamilton wrote on Tue, 30 November 2010 17:27

Is 2ga 75' cable and 100A 3P enough for 24,000W?

barely, if the cable only has 60 degree insulation...it's enough w/ 90 degree insulation though (although still closer to it's capacity than i'd typically recommend)

shane;
you're drawing ~67 amps a leg (at max) and stranded #2 cable is only good for about 80 (w/ 60 degree insulation)

you might consider upgrading to 1/0 or 2/0 so as to reduce the actual temperature of the cable...even though you're not at capacity yet

mind you, this kind of issue doesn't sound like a power issue, more like an actual dimmer issue or a data issue actually...did anything else on the same dmx line have problems, or just the dimmers?

[Shane Presley]

James Feenstra wrote on Tue, 30 November 2010 21:25

Alan Hamilton wrote on Tue, 30 November 2010 17:27 Is 2ga 75' cable and 100A 3P enough for 24,000W? barely, if the cable only has 60 degree insulation...it's enough w/ 90 degree insulation though (although still closer to it's capacity than i'd typically recommend) shane; you're drawing ~67 amps a leg (at max) and stranded #2 cable is only good for about 80 (w/ 60 degree insulation) you might consider upgrading to 1/0 or 2/0 so as to reduce the actual temperature of the cable...even though you're not at capacity yet mind you, this kind of issue doesn't sound like a power issue, more like an actual dimmer issue or a data issue actually...did anything else on the same dmx line have problems, or just the dimmers?

Hey James thanks for checkin in... the feeder is 90 deg jacket, and it was sitting on the plastic "click n lock, covers over and ice surface, so I was confident that it would "keep cool enough for this show"...
hydro inspector stickered and rated this cable for 150 amps so I don't see it having a problem with a 100 full on.

Agreed, but it's entertainment grade 90 deg jacket

I used 4 ott 10' jumper to get from the transformer to the etc sensor, then the 75' run to the behringer, so I don't think it is a feeder issue...

here's the path...
NSI console--25ft DMXcable--ETC sensor rack---75ft dmx cable----Behringer dimmer...

[Shane Presley]

Alan Hamilton wrote on Tue, 30 November 2010 17:27

I wonder if tight-packing them in the rack contributed to an overheating issue? Also, what is the back of the rack like (filled with rack panels or ventilated in some way)? The one thing that pulls me away from blaming the dimmers is that (as I read it) all 4 started acting up at once. Even with overheating I'd expect them to not react similarly at the same moment. It wouldn't surprise me to see them all have the same failure mode when overheated, but I wouldn't expect them all to have that happen at once.

Hey Alan - I wondered about running them all together as well, but you would think they would think that ultimately someone might use them tightly packed, but I hear ya.  Only the bottom four dimmers were on, and it is an open backed rack, becuase I put the socas right on the dimmer pack itself.
They are back to front cooled so I wouldn't think staking them would cause them to over heat, but who knows.... also like I was saying to James, this was in an ice rink , with the ice IN, so the ambiant temp was fairly low ( dimmer friendly if you ask me), so I would of thought cooling would be an issue for either the feeder or the dimmer... but low and behold.... I was wearing my jacket the whole time, and we had a small 15 amp heater keeping our feet warm. Maybe that's what put it over the top for the power...lol

These are the top four dimmers when they were in another rack... they are still on twistlock plugs, whereas the bottom four are hardwaired to the distro in the bottom of the rack....
You can see the soca mounted on the back - so the dimmer is open just like this...

[Silas Pradetto]

James Feenstra wrote on Tue, 30 November 2010 21:25

Alan Hamilton wrote on Tue, 30 November 2010 17:27 Is 2ga 75' cable and 100A 3P enough for 24,000W? barely, if the cable only has 60 degree insulation...it's enough w/ 90 degree insulation though (although still closer to it's capacity than i'd typically recommend) shane; you're drawing ~67 amps a leg (at max) and stranded #2 cable is only good for about 80 (w/ 60 degree insulation) you might consider upgrading to 1/0 or 2/0 so as to reduce the actual temperature of the cable...even though you're not at capacity yet mind you, this kind of issue doesn't sound like a power issue, more like an actual dimmer issue or a data issue actually...did anything else on the same dmx line have problems, or just the dimmers?

James, #2 with 90 degrees C rated insulation is good for 190 amps according to the NEC for non-enclosed wire (aka, individual strands not in a jacket or pipe).

[Silas Pradetto]

Shane Presley wrote on Tue, 30 November 2010 15:49

I tend to believe that it was from over-heating ( even though the packs fan output was cool. The filter exhhaust areas were dusty but not chocked. I'm going to give them a cleaning, and going over when I get the chance...  Thanks for everyone inputs to date - I know behringer product is often in question, I thought that I a had a decent product from them that would work.. I'm going to re-evaluate their use... Any got a used 24 ch ETC for sale ?

I have 24 channels of NSI DDS9800 for sale, they're 2.4k per channel, rack mountable and already have socapex!

[Shane Presley]

Yeah I saw your ad  - I just sold my 4 x LD2400 leprechons. I'm really interested in an ETC 24 ch, 2.4 sensor rack only. It seems to be the choice around here,(and when I say here, I mean the Ottawa area) so cross rentability would be the order of the day....

[Alan Hamilton]

FWIW I wasn't so much thinking about the 2ga going up in flames as I was wondering what the voltage drop would be.

[Shane Presley]

SO just as a follow-up, I used the dimmers again yesterday in a different venue - single phase 100 amp source L1, and L2 lit up.  Tried the dimmer, and it was making that power buzz sound again, and the lights were acting the same way, so now I know the dimmers have issues.  I brought my motion labs distro and plugged in the 4 dimmers above these(they are configured with 30 amp plugs as opposed to direct into the panel in the bottom of the rack. All was good.... wierd that all four dimmers are "pooched" at once...

[James Feenstra]

could it be a data issue with them?

usually a pooched dimmer won't light up at all, not randomly do stuff

[Shane Presley]

Maybe James - but I took the same data/cable path(s), nsi console, and just bounced the soca outputs up to the top 4 dimmers from the bottom, and all was good - so everything outside the dimmer rack is now "out of the trouble shooting loop" if you will.... I'm thinking it's a wiring issue now inside the dimmer, or something "blown" inside , but why all four at once, not sure.. and why all of a sudden - since they were working fine at the dog show, then just at once, decided to "mis behave". More investigation to follow