Footer4321 said:um... you shouldnt ever touch a cam when power flowing through it.... now thats arcing....
Diarmuid said:
Chris15 said:"Even a single power lead with a 650W lantern running on the end will cause a decent spark inside the socket at the point of disconnection. Each time this happens, the socket and the pins get damaged. This damage causes resistance at the join – and given enough damage, that could lead to a fire. If you have ever seen someone disconnect a three phase connection under load, it is the same effect, but multiplied significantly.
That kind of disconnection will ‘blacken’ the interior of the socket, and cause it to fail its next electrical tagging. It could even potentially ‘jump out’ and get you depending on the amount of load, age/wear of the connection etc." http://www.juliusmedia.com/cxweb/article.asp?ID=446
If the connection is through a dimmer and the dimmer is at a low level, the effect will not be as profound but will still occur, hence why one should not hot patch.
Mayhem said:The other important factor to consider is that hot patching is often done to test a (potentially) faulty piece of equipment.
Lets go back to the 650W Fresnel and imagine that you just pulled a pair from the rig because they didn’t work and threw the breaker on the dimmer (plugged into the same circuit). So, you grab one and plug it in to a live feed.
What would happen if the lamp base had failed creating a dead short and you are now holding the plug in one hand and about to stick it into the end of an extension lead that you are holding in your other hand?
Diarmuid said:Would you get a electric shock from the plug, as it was shorted, and (i dont know the science behind this) but would that cause the current to be different to what it would of been, if it was flowing through the lamp, i.e. stronger or more intense and as such cause the spark inside the socket/plug to be larger, and thus have a greater chance of getting you?
Also, surely hot patching is quite a bad method of testing a fixture, for example if the lamp hadnt blown, but something in the Internally Wired Bar was wrong, is it not possible that by hot patching the light, without pre-heating the filament, the lamp would then blow anyway.
Radman said:This is one more reason someone should invent wireless power cables. Or a connector with a switch that must be thrown to connect/disconnect. Probably wouldn't be viable for cams though, too much current!I admit at times I do hot patch lights sometimes, but then again I never have anyone helping me, so it would not fit into my schedule if I had to go to the board every time I plugged something in.
Lightingguy32 said:....it may lead to failure of equipment eventually
Lightingguy32 said:
Now we need to remember that even though the DMX output might be 00, many dimmers have a preheat setting so that there is a small amount of power going through the lamp so that lamps don't blow as quickly, so this can still cause arcing, since with most dimmers, the full voltage is there, just not all the time, so effectively there is less voltage.
i disagree completely. we were doing a show and needed little lights like 3 watts so we wired about 4 of them up like we wanted to give us a 12 watt load. on a 2.4kv dimmer they lit right up bc there was no ghost load. and this was with the board set to 00 and off...on newer dimmer racks with a processor you can change settings directly on the rack and override the settings on the board.
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