Power zaps in my darkroom

tbm · Jul 29, 2006

My darkroom is in my garage here in California, as are a refrigerator and a separate combo refrigerator/freezer. Many times when I press the 'print' button on my StopClock timer to start the enlarger and make a print, the light shining down on the easel and paper lessens briefly. I can tell that the culprit is the aforementioned freezers as they power up to maintain the temperature dictated by their thermostat settings. Of course, the darkroom electricity is not on its own separate line. What do I need to stop this interference?

blaze-on · Jul 29, 2006

Is your enlarger plugged in to a surge protector? It may help (may) with your problem, but definitely will help in the event of a spike, which could damage the power unit. All my electric gizmos are in surge protectors.

I would contact your local power supplier, ask for an Energy Services Specialist and see what they can come up with. A separate circuit would be ideal...

dancqu · Jul 29, 2006

tbm said:
...they power up to maintain the temperature
dictated by their thermostat settings.

Do not allow that thermostat to dictate! Reset
it for the duration of your darkroom session.

This West Coast heat wave we've been having
must have had those freezers going most of the
time. Is that garage air conditioned? Dan

resummerfield · Jul 29, 2006

dancqu said:
Do not allow that thermostat to dictate! Reset it for the duration of your darkroom session.....

My suggestion, too. Otherwise, you would need a stabilized power supply, probably with a battery backup. Pretty expensive compared to turning the thermostats down.

Monophoto · Jul 29, 2006

Surge protectors won't help. And the problem is not one that the power utility will be able to help you with - it's completely within your own premises and you have to either do the work or hire an electrician to do it for you.

The problem most probably is that the circuit that feeds the garage from the main panel in the house is too small for the aggregate loads that it is trying to serve. I suspect it is a 15a circuit from the days when the house was originally built and before the refrigerator/freezer and darkroom came along. And the only practical solution is to run a second circuit. I suggest segregating the darkroom loads since they are sensitive to the flicker caused by compressor in the refrigerator/freezer..

tbm · Jul 29, 2006

Everything in my darkroom is plugged into a surge protector. In spite of this, the refrigeration units still zap power quickly. Someone recently told me to buy a voltage regulator and assured me that would correct the problem. Do you have any experience with a voltage regulator?

Monophoto · Jul 29, 2006

A voltage regulator is a "band-aid" fix that may or may not solve the problem.

The issue is voltage drop - the current draw through the circuit when the refrigerator/freezer compressor starts (which is about 600% of the normal current drawn by the compressor motor) causes too much voltage drop in the circuit to the garage. A regulator may help - provided it has the dynamic range required to compensate for the voltage drop.

The best solution is to either upgrade the circuit, or else install a separate circuit to the darkroom.

Kino · Jul 29, 2006

I have a huge UPS on my enlarger and Jobo processor; it works great! Got it free from a local office complex when the battery went bad; it protected a rack full of blade servers. One new battery later, I have a great emergency backup power source for my darkroom.

A good workstation-grade UPS on your enlarger would certainly help, as it would "make-up" the voltage sag as the compressor kicks-in on the freezer. The UPS has a battery that acts as a capacitor to fill in the brief voltage sag, and could even allow you to continue printing in the event of total electrical loss (depending upon voltage demand from your enlarger and your UPS capacity).

In any event, it might help and even solve your problems short-term, but it only serves to give you a false sense of security; get the upgraded breaker or run a new circuit as monophoto suggests or risk a fire.

Kobin · Jul 29, 2006

Or you could install a timer/integrator like MetroluxII or the RH machine, and the timer will compensate for brightness fluctuations.

K.

Lopaka · Jul 29, 2006

Assuming your enloarger plus timer doesn't draw more than about 400 watts or so, a workstation grade UPS is the cheapest short-term answer - about $100. Long-term you need a separate appliance-grade (20 amp) circuit for the freezers to keep the compressor start-up issue from causing problems with other things. (generally required under current code most places). Meanwhile, try and keep cool. 95 F here today, same or a bit warmer forcast for at least the next 3-4 days with high humidity. Whew!

Bob

Jim Jones · Jul 29, 2006

I agree with Kino. Being a cheapskate, I use an old Raytheon Voltage Stabilizer using magnetic amplifier technology of many decades ago, but it does reliably provide constant output over a fair range of input voltages. Unlike an UPS, it doesn't help if the power fails.

raucousimages · Jul 29, 2006

Don't screw with electricity. Put the darkroom on it's own breaker.

tbm · Jul 30, 2006

I asked my mate about my zapping problem, and he laughed and showed me what is wrong: The electrical cord that gives power to everything in my darkroom is plugged into an outlet behind the two freezers, and the freezers are also plugged into that outlet. To the left of the freezers are a washing machine and a dryer that are plugged into another outlet. Both of these separate electric lines go underground inside a pipe, then go underneath our house to the electric box on the side of the house. The solution? Simple--move the darkroom cord to the outlet for the washer and dryer, for they are run only on Saturday mornings, unlike the freezers which run constantly. Why didn't I think of that? Damn!

Power zaps in my darkroom

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