Power load requirements

[Allen in Montreal]

I am laying out the electric wiring for the darkroom,
I have 3x 15amp lines in to the darkroom, plus overhead lights.
Is there any reason why I should consider more than 3x 15amp lines?

I am running a 200 watt bulb in one enlarger and a 250 watt in the other (never together).
Jobos when running film.
Safe lights, an exhaust fan, 2x Gralab timer and a Bose iPod station. The demand does not seem that high.

The dry mounting press will not be located inside the darkroom.

[Leszek Vogt]

Each line will give you 1800W....so 3 lines would give you 5400W. Hope you are talking about 120Volts. Unless you drag in a mixer or coffee maker, you shouldn't have any issues. What about heat...is your darkroom heated by gas ? These numbers (watts) may be real, but I decided to install 12 gauge wire throughout the house....so even if something or several appliances would come close to maxing out the load, it would not overheat the wires. Cheap insurance. As an ex-firefighter, I can vouch that one of the worse fires to deal with is electrical.....it's difficult to determine where it starts....till the roof is engulfed.

Les

[polyglot]

5.5kW seems plenty to me, so you should be fine. However, most of the items you've listed are not the real power drains and there may be significant others you might want in future:

- a Jobo CPP2 is 1.2kW peak (1kW heater, plus pump, plus rotation motor)
- some LF enlargers are 500W to 1kW
- print dryers can be power hungry, but not when run cold
- drymount press is maybe 1kW or 2kW during warmup
- if you do alt process, a UV exposure unit could be 500W+ easily
- if you get cold in there in winter, a little fan heater will be 2kW+. I find my Jobo at 35C (RA4) keeps the room nice and toasty while printing though!

I have a single 15A/240V line into mine and that's plenty. Runs the Jobo and enlarger easily and nothing else draws any power worth worrying about.

[Keith Fleming]

Think about a small refridgerator (the "dorm room" size) as part of your power-needing mix. Also, my experience was that I have needed about 3 times as many plug-in sockets as I originally thought--the radio, the clock, a desk lamp, etc were all things I did not plan for when the darkroom was built.

I have four ceiling lights controlled by a single switch, but each light socket in the ceiling has a pull chain too. That allows me to turn the lights on and off selectively. For examaple, one is over the sink, and the light works great for evaluating prints in the fixer. When loading film, I can turn off three lights and then pull the chain of the fourth, which is over the area I use for loading and unloading film.

I guess my point is that extra power--and power outlets--may be needed at a later date as your methods change.

Keith

[Jody_S]

3 circuits is overkill. I don't know of any photography-related gear that could possibly require more power than this. In a previous life I was a member of the CMEQ.

[Leigh]

I would run 20-amp circuits rather than 15. Decent AC outlets are rated for 20 amps, and 12-gauge wire will handle it easily.

- Leigh

NB: A 250-watt bulb is only about 2 amps @ 120 volts.

[Louie Powell]

One 15 a circuit should be sufficient for the load. That said, I would probably opt for two 20a circuits. There are two reasons for this.

First, a 20a circuit would provide more capacity for future loads that you can't anticipate now (and that will become absolutely mandatory about a week after you start using the darkroom - DAMHIKT).

Second, providing two circuits would allow you to put the enlargers on one circuit, and all other loads on the other. That way, a load that switches on and off won't cause a cyclic voltage dip that affects the enlargers, and causes erratic exposures.

[Jim Jones]

Keith is right. Insufficient outlets may be more of a problem than insufficient power. I've had over a dozen things plugged in at one time in a small darkroom. It's much easier to provide a surplus of outlets during initial construction than to add them later. Two 15 Amp lines sounds like plenty. Having at least two is a safety plus. You'll still have some power and lights if one line kicks off. Do consider ground fault circuit interrupters throughout the darkroom; it's a somewhat wet environment.

[ic-racer]

Go with 20A. Things like vacuums and power tools, air compressors, etc that occasionally might find their way into the darkroom could benefit from the higher rated circuit. I have two 20A circuits with GFI breakers for power and an additional 15A circuit for lighting. The 220V Durst is on its own breaker. The only drawback is that working 12G wire is more tedious than 14G.

[Leszek Vogt]

It's doubtful that you'd need to compensate for the "peak power", since you're not running table saw or a bed w/vibrator (dark enough, eh ?)...but I'd consider a 20A circuit along with the other two 15A type. I mean, more or less interlacing. If you ever need to install a heater, or A/C on wheels, or some other juice robbing gismo....and it's that much easier on the system and on you. Indeed, GFI's where you'll have any potential splashing....it's important enough to repeat it As an afterthought, you may want to set up several switches, where they would be most strategic for you....flipping the work light (whichever color you use), be able to shut off the main light/s, etc. You may want to get bit fancy and set up 3-way, where you control the light on/off from another spot in the room, like close to the door perhaps.

Les