Is a stage box with an iron grid safe using this way?

Question

See also my previous question:

How should I bypass switches

Where I made a circuit directly by mains, and as proposal by very useful comments to use a separate 'control' circuit at 9 or 12V.

However, according to this video:

How to Build On-Stage Light Boxes for Your Band

the switch under the 'plateau' is directly connected to 220V.

However, in my case I want to make a very important change: I don't want to use plexi glass, but a metal grid (like this):

I assume it would not safe to make a switch directly under this iron grid that is connected to 220V? Or is it actually not really safe for the plexi glass solution as in the YouTube video neither?

(Btw, I think according to the related earlier question, I'm going for a transistor/relay/triac solution anyway).

And a side question: another band I seen, uses a foot switch instead of a switch under the grid. I'm almost sure that foot switch is connected directly to mains (meaning 220V goes through it). Now this is seen quite often with living room lamps etc... but I wonder if this is safe on a music stage (what if someone would drop beer over it, and the foot switch is not 100% 'closed' somehow) ?

Answer 1

There absolutely is no issue in using a correctly rated momentary switch to turn on and off a lamp directly. After all, our houses are full of wall switches, foot switches, and even not so safe kinda sloppy switches from non controlled markets.

But there's a catch: there is no issue if you can ensure that the switch will operate in a proper environment at all times. If you can understand what a proper environment is, and enforce it, then go ahead with whatever design comes to your mind.

Using a low voltage switching circuit is certainly a hassle, because you need a transformer, a PCB, whatever: it's a mess.

But consider this: you can buy an off the shelf relay, connect the mains voltage to it, put everything in sealed box like what they use to make electrical connections in gardens, and just run around your low voltage control wires.

With low voltage control you can do a number of things that are more difficult and costly to do with the mains directly: you can add crappy foot switches everywhere, and enjoy the light going on and off when your drunken guitarist drops a pint on it while smiling to that girl that was "definitely looking at him". You can add alwasy on, always off switches at no cost. You can parallel foot switches so that you can turn the lights on and off from various points in the stage. You can add a microswitch to your drummer pedal and have cool, perfectly timed, blinking lights. You can even program an arduino or whatever to produce super cool effects in the future, if you want.

Be safe on stage, if you have to ask if it is safe assume it is not safe.

Answer 2

The light box video has design flaws but works with the weight of stepping on one side only. But at least it is rugged and insulated. The choice of the >=20A switch and it’s height are critical.

Safety of using a metal grid instead of 1/4” plexiglass depends on your common sense of insulation and keeping it dry. Grounding it may or may not be a wise idea with unknown guitarists vacuum tube amps , leather shoes and leakage hum.

( some vacuum tube guitar pre-amps may have unsafe leakage leakage current available to go thru the strings. Leather boots are known to be good for small current leakage from sweat absorption, good for anti-stat, but may induce hum if there is leakage to metal grid. Then again, if grounded , it may also increase or reduce hum. and impossible to predict if it is safe)

Enclosing a 500W Halogen heat lamp is not a great idea but for pulsed flood light, it does the job OK.. Consider cheap LED flood lights, faster response time without the tungsten PTC time constant. But I think the stomp timing effect gives it a smoother power effect with the one foot stomp control on the corner switch.

Plexiglass vs metal grid? I think you could make the metal grid work, if you guarantee the switch to be insulated under all conditions ( coat exposed contacts with silicone) and ground the grid.

Answer 3

It will be safe if the grid is grounded and of course the switches insulated and designed for this purpose (strong enough mecanicaly). Yet, it will be safer with 12V. As Vladimir Cravero said, with 12V you have more flexibility for further sophistication without worrying too much about safety.