ETC Sensor Rack Dimmer Bypass

[LPdan]

A school would like to replace a couple dimmer circuits with fixed power outlets. Fixtures using these outlets could be switched using a CS Relay in DMX detect mode. Would there be any concerns in simply bypassing the dimming circuitry within the D20AF module, leaving the circuit breakers inline? Understand workmanship, etc.
Thanks!

 

[Shawn Fidler]

The constant power CC20 modules are inexpensive in the grand scheme of things, will free everyone from awkward conversations if something else goes wrong in the rack later, and will leave you with spare D20AF's when you need them someday.

 

[LPdan]

The constant power CC20 modules are inexpensive in the grand scheme of things, will free everyone from awkward conversations if something else goes wrong in the rack later, and will leave you with spare D20AF's when you need them someday.

Shawn, I just saw how inexpensive the CC20s are. I agree, much cleaner to just buy them and have spare dimmers. Thanks!

 

[derekleffew]

Would there be any concerns in simply bypassing the dimming circuitry within the D20AF module, leaving the circuit breakers inline?

As has been said, many reasons against doing this. The most pragmatic one is that it's not easy, if even possible, to bypass the SSR on a Sensor, as it is with other/older dimmer modules. *cough* CD80.

Fixtures using these outlets could be switched using a CS Relay in DMX detect mode.

Pretty sure a dual R20 module would be less expensive than a single CSRelay. You'd need to do the "DMX detect" a different way though.

 

[Malabaristo]

As has been said, many reasons against doing this. The most pragmatic one is that it's not easy, if even possible, to bypass the SSR on a Sensor, as it is with other/older dimmer modules. *cough* CD80.

It's sorta possible, but you have to cut open the power cube and scrape away some potting compound to do it. Definitely not a good or correct approach to something that could start on fire and/or electrocute someone if it fails. Liability is a thing...

Also, the chokes in a dimmer module are an important part in determining how much fault current the rack as a whole can handle safely. In bypassing or removing those, you're creating something that looks the same in normal operation, but is potentially much more dangerous when something goes wrong. The proper CC20 modules achieve the same results by including fuses in place of the chokes. Those fuses have a higher rating than the breaker so a normal overload (like 30A on a 20A circuit) will just trip the breaker. In a more extreme failure, those fuses can react faster than the breaker can trip and that limits the total amount of energy released.

Oh, and in case anyone decides to be half-clever: leaving the chokes in is not a good solution because they're actually more likely to be the cause of problems than the SCR when powering things that don't like dimmers. That's especially true for higher rise-time modules like the D20AF since the chokes are bigger.

 

[LPdan]

Thanks for the replies and info. I always appreciate understanding why something isn't a good idea rather than just "it's bad"!

 

[microstar]

As has been said, many reasons against doing this. The most pragmatic one is that it's not easy, if even possible, to bypass the SSR on a Sensor, as it is with other/older dimmer modules. *cough* CD80.


Pretty sure a dual R20 module would be less expensive than a single CSRelay. You'd need to do the "DMX detect" a different way though.

Looks like street price of an R20 is around $475 and the CSRelay is $240. But you get two 20A circuits with the R20 and only one with the CSRelay.

 

[JD]

Another concern has to do with the fault current interrupt rating of the circuit breaker. When you bypass the SSR/Choke, the potential fault current is higher. The breakers in the CC20 are approved for this higher fault current.

 

[Jay Ashworth]

I'll be clearer about it: If your fire insuror finds out, after a fire, that you were even *talking about this in public places*, they will deny your entire claim, flat. UL Listed, unmodified, every time.

 

[tyler.martin]

Keep in mind, that ETC will warranty their LED fixtures operating on a D20 module in switched mode.