Is it acceptable to put 4x S4s on a dimmer?
- Thread starterderekleffew
- Start date
waynehoskins
Active Member
My opinion = yes.
Barring obnoxiously long cable runs, yes.
soundlight
Well-Known Member
propmonkey
Well-Known Member
isnt that way they made the lamps 575w?
David Ashton
Well-Known Member
Pip
Active Member
Well, it's possible, but I wouldn't say it's advisable.
Consider the almighty power equation:
Watts equals Volts times Amps:
W = V * A
You have 4 instruments, 575W each, for a total of 2,300W (2.3kW):
4 * 575W = 2300 W
That's cutting it fairly close if you're on a 2.4kW dimmer. Let's look at that in terms of current (Amperage)
Going back to our power equation...
2300W = 120V * A
A = 2300 / 120 = 19.17A
Consider the almighty power equation:
Watts equals Volts times Amps:
W = V * A
You have 4 instruments, 575W each, for a total of 2,300W (2.3kW):
4 * 575W = 2300 W
That's cutting it fairly close if you're on a 2.4kW dimmer. Let's look at that in terms of current (Amperage)
Going back to our power equation...
2300W = 120V * A
A = 2300 / 120 = 19.17A
David Ashton
Well-Known Member
Pip
Active Member
Yes, but that is a built in safety feature. By saying that and going about business in that manner, you're circumventing one of the ways these things are designed to keep you (and your audiences, your facilities, etc) safe.
It's not just about the inconvenience of popping the breaker - it's about actual safety when dealing with dangerous electrical equipment.
It's not just about the inconvenience of popping the breaker - it's about actual safety when dealing with dangerous electrical equipment.
David Ashton
Well-Known Member
What I said is that it is safe to run 2.4k on a 2.4k dimmer because there is a safety factor built in, unlike others who were saying that you should further de-rate it to be on the safe side, I am sure no-one would ever consider pushing them a bit further even though you could possibly get away with it.
David Ashton
Well-Known Member
I was taking that voltage range as a given, but at 120V, 115V 575W lamps draw more that 575W... Rather my sums put it at about 626W, 5.2A. 4 times that and you are into the range where a fuse will trip in time but a breaker may not...
Put a voltage spike on that and I think you'll find breakers going tripsies.
Can you do it? Yes. Should you do it? perhaps not...
Put a voltage spike on that and I think you'll find breakers going tripsies.
Can you do it? Yes. Should you do it? perhaps not...
David Ashton
Well-Known Member
If you don't use the correct voltage lamp you're very likely to blow it as the life reduces dramatically, but in answering questions like this it is fair to assume that a 575 lamp is using 575w.If you look at fuse ratings you will see that they run at a slight overload for a long time, certainly up to an hour.Over-running a lamp is not a linear increase as the resistance is very non linear with temperature so a simple calculation is inaccurate.
STEVETERRY
Well-Known Member
David Ashton
Well-Known Member
Steve, could we have some examples of 2.4k dimmers which only take 1.9k as I've never come across any in Australia?.
Err I thought it was a not uncommon practice for our American brothers to use a 115V lamp on a 120V supply to get some extra brightness. Someone wanting brownie points can go back into the archives and find Ship's percentages for lamp life change, colour temperature change, output change etc with over or under voltaging a lamp.
I looked at a breaker curve a while back and from memory, you could run indefinitely at 127%... Fuses are normally a little more sensitive.
Yes the resistance is very non linear, a 500w flood lamp is only a few ohms cold at DC... I suspect current draw will still go up, though it won't be linear and hence my number will be out...
