ETCP Problem Help

[IndyBonesLX]

Hello!

I've been studying for ETCP for a few months now and am planning to take the test in just over a week.

I have been absolutely haunted by one question that I cannot seem to wrap my mind around and keep grtting lost in. I was hoping someone could help explain to me how to solve this. I'm nearly pulling my hair out!

Thanks in advance!

 

[TimMc]

I believe the answer is A.

100 PAR64/1k, 25 control channels = 4 fixtures per control channel; 2.4kW dimmers means 2 dimmers per control channel. 50 dimmers.
75 Source 4 575, 25 control channels - 3 fixtures per control channel, 2.4kW dimmers means 1 dimmer per control channel. 25 dimmers for a total of 75. The 96 rack is one unit and best meets the criteria.
24 individual 208V circuits for movers, so the bigger distro gives the lowest piece count.

Are there other questions that use this light plot specification? I see a couple of other things that would conflict with the choice of dimmers and distros.

 

[Crisp image]

I believe the answer is A.

100 PAR64/1k, 25 control channels = 4 fixtures per control channel; 2.4kW dimmers means 2 dimmers per control channel. 50 dimmers.
75 Source 4 575, 25 control channels - 3 fixtures per control channel, 2.4kW dimmers means 1 dimmer per control channel. 25 dimmers for a total of 75. The 96 rack is one unit and best meets the criteria.
24 individual 208V circuits for movers, so the bigger distro gives the lowest piece count.

Are there other questions that use this light plot specification? I see a couple of other things that would conflict with the choice of dimmers and distros.

I concur with your calculations too.
It is always good to know how to calculate things like this in our world. I have a trainee at a venue that when asked if I can run all 12 fixtures off 1 10a 240v said "we always do". I then asked how do you know that you can? "We don't have time to work it out now we have to install them" was the reply. WRONG ANSWER! So we stopped for 1 min and worked out that the fixtures were 155w each so now we know for sure that we are good to go.
Have a great day
Regards
Geoff

 

[Footer]

You need to define inventory.... and I think this question is actually asking what is the least number of dimmers you can take. Personally, we all know we'd just take the 96 rack and two 24 ways and call it a day. But, they want to know how many dimmers you need at a minimum.

So... to power the 100 1k pars on 25 channels you need 50 dimmers. To power the S4's on 25 channels you need 25 dimmers. So, that puts you at 75 dimmers. A 96 rack will work but they want the least inventory. So, that combo of multiple dimmer racks will give you the needed 75. The movers are easy... 1 Mac2k and 2 Mac600's per circuit on a 12 way. Now, personally I'd shoot the tech at the shop who pulled me that dimmer combo and made me tie all that stuff in so they could save sending 21 extra dimmers.

 

[Footer]

I concur with your calculations too.
It is always good to know how to calculate things like this in our world. I have a trainee at a venue that when asked if I can run all 12 fixtures off 1 10a 240v said "we always do". I then asked how do you know that you can? "We don't have time to work it out now we have to install them" was the reply. WRONG ANSWER! So we stopped for 1 min and worked out that the fixtures were 155w each so now we know for sure that we are good to go.
Have a great day
Regards
Geoff

The answer is D.

 

[TimMc]

The answer is D.

It goes back to your initial question: what is "inventory." I took it to be piece count. 2 racks.

The bigger question is how to provide power to this rig, as just the PAR cans will pull ~330 amps/line by themselves. We have 2, 200 Ampere 3 phase services. But that's not part of the question, so far.

 

[Crisp image]

The answer is D.

Yes D would work. I read it as the least amount of inventory (physical items that we have to move and not outlets) to make it happen. Will our answers get the rig up and running? Of course it will. As always there are many way ways to skin a rabbit but the end result is it is skun.

 

[MNicolai]

Is this an official ETCP practice question? A question referencing "Source 4 Lekos" shouldn't be anywhere near an accredited exam.

 

[STEVETERRY]

Is this an official ETCP practice question? A question referencing "Source 4 Lekos" shouldn't be anywhere near an accredited exam.

We try, and sometimes we fail in favor of "generic speak".

ST

 

[chawalang]

Does the ETCP exam have questions like this concerning the use of LED fixtures?

 

[danTt]

I think that's a question from the practice exam that's been available for a decade.

I know the actual exam sees refreshed questions, and from a gear list alone id hope few of those fixtures were on a current question.

I'm not following as closely as I once was, but the etcp marketing/push/support seems to have gone downhill over the past few years. I don't think it ever hit the industry share it needed to.

 

[Footer]

I think that's a question from the practice exam that's been available for a decade.

I know the actual exam sees refreshed questions, and from a gear list alone id hope few of those fixtures were on a current question.

I'm not following as closely as I once was, but the etcp marketing/push/support seems to have gone downhill over the past few years. I don't think it ever hit the industry share it needed to.

Outside of installs, nope. That is the only place I see it anymore is when working on capital projects. Its an easy way to make sure your vendor at least has someone who might know whats up.

 

[derekleffew]

Agree "amount of inventory" is vague. Totally ignoring the incandescents, 24 moving lights = one 24-way distro. The only acceptable answer is A. Done. The others are red herrings whose only purpose is to obfuscate.

Venue has 2x 200A switches. Just the incans is 396A per leg. So much for "You must allow for everything at full."

Like the gear list, this question is old, obsolete, and needs to be retired.

 

[Crisp image]

Agree "amount of inventory" is vague. Totally ignoring the incandescents, 24 moving lights = one 24-way distro. The only acceptable answer is A. Done. The others are red herrings whose only purpose is to obfuscate.

Venue has 2x 200A switches. Just the incans is 396A per leg. So much for "You must allow for everything at full."

Like the gear list, this question is old, obsolete, and needs to be retired.

Maybe the question is outdated however the knowledge of how you get to the answer is not. While we have a changing world in terms of equipment the calculation process is still valid. Yes a better example could be used but the context of the question still remains.

 

[IndyBonesLX]

So questions from the practice test are actually rejected exam questions. I was told not to worry about this question as it isn't a good one, but I was curious how you would solve it anyway.

And this question is self contained so nothing else references it.

I didn't expect such a debate!


Thank you for all the input!