So tonight I headed over to tomorrow's wedding venue to rig my photobooth ahead of tomorrow's wedding. I won't get a chance tomorrow, so thought I'd better get it done now. I'd asked the bride to make sure there was power available, and although she forgot to run the necessary cable, it wasn't a problem.
What was a problem however, was the possible load. Now, this is a marquee wedding, and I've run Photobooth's in marquees lots of times in the past, but this time the electrics guy was slightly concerned when I told him I had 2 x 250w strobes. Now, to my ear, this means, not much power as flash heads go, but I recognise that it's a fair bit as far as wattage goes. He said it shouldn't be a problem and he'd run a cable from a nearby outbuilding tomorrow, but that it was best not to run it off the generator.
Now then, I think I need a lesson in some rudimentary electrics. He was talking about needing 16amp cables or some such and pointed out that my cable (that I've used for years) is 13amp. I was pretty lost by this point and it made me realise that I need to be better informed on this stuff, if only to put the right questions to the B&G in the future.
SO. Can any physics geeks bring me up to speed on electrons and all that jazz? Watts, volts, ohms etc etc. I'm not looking for the whole thing, but an understanding as it pertains to flash usage at weddings would be brill!
VB would work. 250 W/S lights are pretty small, and only use a lot of power for an instant...and that actually comes off the capacitors. If you're worried about it, turn your modeling lights off and get an extension cord with the biggest internal wiring you can find. I've run a WL X3200 (1350 W/S) off a hundred feet of extension cord with no problems before.
Even if you fired two of them continuously you wouldn't need a 16amp cable. Basically strobes use about as much as a lamp, except when they are recycling. That depends on the rate they recharge. If your strobe has a built in fuse, you can assume that the strobe uses about 70% (at the most) of that when recycling with the modelling lamp on. To put it in perspective, I regularly run a 1200 and 2 600's off of a 15 amp circuit and I've never had a problem.
Do you mean 250w/s maximum output, or 250w power draw? They are not the same units.
Either way, it's the CURRENT you want to look at, not the power. Current is what is going to trip the breaker if the load is too high. Look at the maximum current drawn by your strobe (should be somewhere on the strobe in unit "amps" or "A"), then report to the electrician.
Probably the OP is talking about a pair of 250 watt-second flash units, which are very low power flashes. You don't need 16-amp cabling for that. The tech guy probably interpreted your comment to mean you were running a pair of 250-watt continuous light bulbs, and even then, you really wouldn't need a 16-amp cable unless he was also running other equipment on the same cable.
The larger the capacity of the cable, the lower the resistance of the cable, meaning it will generate less heat when conducting the same amount of electricity. The main concern is overloading the cable, melting the insulation, and causing a fire. With a pair of 250-watt-second strobes, you're highly unlikely to do that with a standard 13-amp extension cord in good condition.
But the VB mini is fantastic for low-power strobes for a photobooth. Definitely give in to the temptation to use this as an excuse.
They are 250w/s. Not sure of the maximum current draw as they're over at the venue right now. Will need to have a look tomorrow. Either way, I'm sure they'll be fine, it's just good to have more rather than less understanding.
As for speedlites, I only have 3. 2 x 430EXII and 1 x 580EXII. I use these mainly for dancing so I'd prefer not to. Not to mention the recycle times are comparatively crap.
Its the draw on amps that count. Peak draw in particular. You can probably see that on your light manual, or the lights themselves, or the website white paper on them. ??
The gauge of cord over 100' will probably need to be at least a 12, 10 if the draw is more than about 20 amps peak.
I vote for a VB mini too. I am still using a VB 1 and it works great if I don't run too fast.
Tony, as most people have said here watts are different to w/s the power measure of your flash. You need to know the actual power draw.
Be slightly careful with the amp numbers people are throwing a out here too as they mainly based off the US 110V system not the UK 250V system. Power = current * voltage.
well, if you have the bowens gemini 250watts you are good to go. I have never heard of a 16amp breaker, so I am guessing it is a 15amp, doesn't really matter though. since you are running on a 110 volt source and VOLTS X AMPS = WATTS your lights are drawing around 2.5 amps. which also makes sense becasue you have a 5amp fuse on your lights. Basically you could be running 6 of your lights at full power and you would still probably be fine.
ai3x wrote:
Tony, as most people have said here watts are different to w/s the power measure of your flash. You need to know the actual power draw.
Be slightly careful with the amp numbers people are throwing a out here too as they mainly based off the US 110V system not the UK 250V system. Power = current * voltage.
Never mind my post then.
Bowens uk site is pretty crappy, cant even get to the specs for the unit.
Tell him you'll be fine on a regular 15A (amp) circuit.
From Paul Buff (http://www.paulcbuff.com/faq.php#flashunits): Q. What is the average current draw of Paul C. Buff™ flash units? A: Einstein™ units draw an average current of 5 amps during recycle and AlienBees™ and White Lightning™ flash units draw an average current of 6 amps. This means that if a light were fired every time it recycled, the average current draw would be 5 or 6 amps. At the beginning of each recycle, the lights draw a peak current of about 16 to 18 amps for about 200 milliseconds. This is well tolerated by household circuits and breakers. A typical circuit breaker will tolerate three flash units in normal use. When the lights are idle and not being fired, the current draw is essentially that of the modeling lamp - 1 to 2 amps per unit....Show more →
Really appreciate all the information here guys, I may look at a VB as my next purchase. In the end everything went off smoothly and while the modelling lamps dimmed a bit during the recycle, everything went off without a hitch!
