Leaving Dimmers on always? Controller?

[techieman33]

About the only time my CD80's get powered down is when the building loses power, which is typically only once a year when they intentionally kill power for the generator test. Other than that the only time they have been powered down was when we lost a phase in the rack and powered it down to trouble shoot.
As far as powering down for a light hang? I've never done it, nor have I ever seen or heard about anyone doing it until U/variable brought it up. Maybe it was more common with older dimming systems? There are only 5-6 volts coming out of my CD80's, not enough to cause me any concern. For that matter most us of have plugged plenty of fixtures into hot circuits without ever giving it a second though. And of course all of the things we plug into power at our homes and other places everyday.

 

[DavidNorth]

I would turn the console off every night, unless it the only method you have for turning on lights [no arch system]. The iRFR scenario above might require leaving the console on.

There are few reasons to turn off the dimmers at night. Safety, as listed above, is a great reason to consider but rarely practiced in the US. In rare cases, we have seen situations in which dimmers were driven on due to a lightning strike or SCRs were stuck on due to failure. If a fixture was plugged into a dimmer while on and pointed at scenery or soft goods, that could [and has] cause a problem. Again, rare.

Breakers should only be used as switches if they are rated for use as a switch. This information is available on the spec sheet for the breaker. ETC dimmer breakers are suitable for switch use. Many normal GE, SquareD, etc breakers are not switch rated. Breakers can fail on or off and some old breakers, like Heineman units, can arc across the contacts, only allow part of the current through and get warm as they become resistive.

Bill's point about humidity is very valid. If you are working outside in the south, have weak air conditioning, or are in a damp basement, leave all the gear on all the time. I've serviced damp environment gear, and it was never reliable due to corrosion issues.

It is difficult to say how much power is available at a turned off dimmer as this depends on how much leakage current is allowed by the specific SCR/SSR package used in the design. Therefore, since we never really know, ideally, the breaker for the dimmer will be turned off whenever any circuit service work or plugging occurs. I only turn off the breakers when working on the circuit, myself, and think that would be fine. Do note that even using old, high current, and therefore high leakage current SCRs, does not "burn" empty current when sitting idle when no load is connected. There is not a large amount of "vampire" current being burned by most dimming systems today, minus the power supply.

David

 

[Dionysus]

Personally I say leave the dimmers on 24/7 (mostly). Power down for maintenance or for any time that the building will be empty for more than a couple days. As mentioned most racks are designed to "idle" when not in use, turning off fans and such. You will gain little by turning your average installed rack off for a few hours every night. Absolutely turn your console off every night, unless it needs to be on for some reason.

Id recommend giving your dimmers a cleaning at least once a year! Get rid of that thermal-insulating dust (remember heat kills electronics) and get the dust off of the fan-blades.

As for turning off your dimmers while hanging lights and cabling, that is pointless from the point of view of this electrician. Your electrical connectors are DESIGNED to be plugged in HOT (to a point), yes I'd avoid plugging and un-plugging large loads live especially with dimmers at full. However your typical 500w-1kw lighting load isn't an issue with the dimmer at 0% (more an issue with some connectors like stage pin than others like twist).
The BOND pin is longer for this exact reason, so it makes contact FIRST when plugging in (and visea-versa) and the IDENTIFIED/NEUTRAL and HOT pins contact at the same time.

Kill circuits for maintenance ALWAYS! You don't want an accident. Personally I tag-out, but then again I've worked as an electrician (the construction/maintenance kind) and after nearly dying once I will never make that mistake again! Always remember the wizard's first rule, "People are Stupid".

I reiterate that MOST breakers are NOT designed to be used as a switch. There are some that are, and others that aren't. If you don't know, treat it as it is designed (as an OVERCURRENT DEVICE not switch).

Most venues I know NEVER turn off their dimmer racks. They are on 24/7, some even when the building is going to be dark for a month.

Basically I think everything has pretty much been covered here.

It does not hurt to turn your dimmer rack off at night, and I recommend it for extended "dark" periods. If noone is there to see an issue, things can go bad.

 

[petercav17]

I think its worth pointing out that modern consoles like the Element need to be shut down often. The Element is really just a computer in a custom case. Computers need to clean themselves and clear out memory and such, and they do this by shutting down. Have you ever left your computer on for a long time? It gets really slow and becomes problematic. I figure this is the same for lighting consoles as well. Plus, there is the whole fan issue, and the console could overheat if the electronics are left on 24/7.

 

[Judge]

What Peter said above. All consoles benefit from being re-started as they are computers. The only time I leave it powered up is if I am doing a festival or somewhere that it might get cold or damp at night in which case the small amount of warmth that it generates will keep it free from internal condensation.

And the same goes for dimmers. If anything, leaving them on all the time is just going to get more dust and debris inside.

 

[JD]

So, on the question of how many volts will a dimmer leak a 0%? The answer, 120 volts (or full line voltage.) The problem is, it is the WRONG question. The correct question is how much current will it leak? That answer is "not much." The bypass resistor in the firing circuit lets voltage flow, but the current is so small that even the act of metering it brings it down. Typically, with a 20k/v multimeter, you may see ~75 volts on an unloaded dimmer. Put a 7 watt pilot lamp on as a load, and that drops to the low single digits (if that.) Put a real load on the dimmer and if there is no idle-set, it will drop down into the mv scale, if readable at all. Voltage does not kill us, current does. It doesn't take much current, but it takes more than is available from an dimmer set to 0. (Unless you have a heart condition.) The greater danger is being startled by the tingle on a high ladder and taking a fall! Now, is all this worth powering down the system while doing work? Some may say so. My own opinion is no. Most connectors do not give you the opportunity to come in contact with the hot. Those that do need to be replaced!

 

[Dionysus]

So, on the question of how many volts will a dimmer leak a 0%? The answer, 120 volts (or full line voltage.) The problem is, it is the WRONG question. The correct question is how much current will it leak? That answer is "not much." The bypass resistor in the firing circuit lets voltage flow, but the current is so small that even the act of metering it brings it down. Typically, with a 20k/v multimeter, you may see ~75 volts on an unloaded dimmer. Put a 7 watt pilot lamp on as a load, and that drops to the low single digits (if that.) Put a real load on the dimmer and if there is no idle-set, it will drop down into the mv scale, if readable at all. Voltage does not kill us, current does. It doesn't take much current, but it takes more than is available from an dimmer set to 0. (Unless you have a heart condition.) The greater danger is being startled by the tingle on a high ladder and taking a fall! Now, is all this worth powering down the system while doing work? Some may say so. My own opinion is no. Most connectors do not give you the opportunity to come in contact with the hot. Those that do need to be replaced!

ABSOLUTELY! And that is exactly why most GFCIs (Class A) Trip at between 4-6mA (I actually just edited the wiki on shock to include this), anything much more than 15mA is potentially quite dangerous.

As I had stated, as long as "plugging and unplugging" is all you are doing, and you are doing it safely. Go ahead and you can do it live perfectly safe. If you are opening things up, turn it off.

I am tempted to open a thread on electrocution and shock, working safe, and the terrible stories Im sure we all have that relate to electrical safety...

 

[JD]

ABSOLUTELY! And that is exactly why most GFCIs (Class A) Trip at between 4-6mA (I actually just edited the wiki on shock to include this), anything much more than 15mA is potentially quite dangerous.

As I had stated, as long as "plugging and unplugging" is all you are doing, and you are doing it safely. Go ahead and you can do it live perfectly safe. If you are opening things up, turn it off.

I am tempted to open a thread on electrocution and shock, working safe, and the terrible stories Im sure we all have that relate to electrical safety...

Not a bad idea for a sticky thread! Electrocution is very misunderstood. There are three different scenarios the press often calls "Electrocution":

1) True Electrocution, where there is enough current conducted through the skin that it either stops the heart or does sufficient damage as to be incompatible with life. Dry human skin can have a resistance of 500k and therefore a great deal of voltage must be present in order for enough current to flow. Moist skin can have a resistance below 1k and requires very little voltage to achieve the needed lethal current. Path is important too. If the flow is from the finger to the elbow, you are probably ok. If it crosses the chest, you have a better chance of having your heart stopped.

2) Arc Flash (or Blast), which is more in line with surviving (or not) an explosion. Most victims die from extensive burns or because the mechanical blast damaged key organs. Although in rare occasions, you may also have been unlucky enough to become part of the circuit as well. (See #1)

3) High Voltage Burns. Often, due to the "skin" effect, where voltage travels on the surface, you may live through this. (Ex- Hit by lightning.) Unfortunately, so much damage may have been done by the heat that the final outcome is death. If a vein of current traveled through you, then this path may become like cooked meat and interrupt some function needed for life.

 

[Dionysus]

Not a bad idea for a sticky thread! Electrocution is very misunderstood. There are three different scenarios the press often calls "Electrocution":

1) True Electrocution, where there is enough current conducted through the skin that it either stops the heart or does sufficient damage as to be incompatible with life. Dry human skin can have a resistance of 500k and therefore a great deal of voltage must be present in order for enough current to flow. Moist skin can have a resistance below 1k and requires very little voltage to achieve the needed lethal current. Path is important too. If the flow is from the finger to the elbow, you are probably ok. If it crosses the chest, you have a better chance of having your heart stopped.

2) Arc Flash (or Blast), which is more in line with surviving (or not) an explosion. Most victims die from extensive burns or because the mechanical blast damaged key organs. Although in rare occasions, you may also have been unlucky enough to become part of the circuit as well. (See #1)

3) High Voltage Burns. Often, due to the "skin" effect, where voltage travels on the surface, you may live through this. (Ex- Hit by lightning.) Unfortunately, so much damage may have been done by the heat that the final outcome is death. If a vein of current traveled through you, then this path may become like cooked meat and interrupt some function needed for life.

My idea indeed. Most people say "I just got electrocuted" and they wonder why I look at them funny, or joke about electrocution. This is particularly a big distinction to me as I have technically been electrocuted, I am told my heart stopped (however thankfully restarted). Electrical safety is no laughing matter. We are way off OP here however (perhaps we SHOULD start that thread indeed). I have also been in proximity of Arc Flash, and suffered electrical burns. I am much more strict on electrical safety than I once was. I also have all the appropriate training.

 

[sk8rsdad]

The most dramatic incident I heard about happened at a company I was working at one summer. It involved a couple of painters, a rolling scaffold and an 22 kV overhead feeder line. They survived but chunks of them were blown off by the escaping steam from the water boiling in their bodies.

 

[Judge]

Oh geez, I can never un-know that now - thanks a bunch!

 

[Dionysus]

Oh geez, I can never un-know that now - thanks a bunch!

You did not know that? I guess not everyone has arc flash certification. Also, don't wear rings while working around power. Can cook your finger or blow it right off... Not to mention ripping it off mechanically.

 

[Casey]

Leave the dimmers on and shut down the console.

The difference is the... How do I say this kindly.... Somewhat consumer psu in the element.

Yoy can leave it on all the time, but after 4 or 5 years if doing so that psu will EOL. Shutting it down every night will extend that considerably.

I would say 75%+ of the problems I have seen with consoles in the EOS family are with the PSUs.

The good news there is that it is a cheap repair and (off the record) is typically one that a technically minded user can do with off the shelf parts (but you didn't hear that from me). So, if there is an operational advantage to leaving it all on all the time, go for it.

Most theatres in the Chicago area leave their dimmers on all the time, and turn their consoles off when not in use. That is my recommendation as well.

 

[Casey]

And regarding the arc flash, yes that is very scary. Not relevant here, bit very scary.

And just to clarify terms, electrocution is death by electric shock: https://en.m.wikipedia.org/?title=Electrocution

If you are still alive, you got shocked, not electrocuted.