View Full Version : Line Voltage Jump
02-02-2006, 10:46 PM
Just thought I would fill you in on what happened to me this week. A client I installed a system for mid-December called to say he had a few lights not working. Went over to see why and noticed he had five fixtures that were not working. All were on three separate runs. First thing I checked was to see what the voltage was at these fixtures. All had at least a 1 volt jump. I know this because on all Cast transformers there is a label for recording all voltage and amp readings per run as well a input voltage and I recorded all. The input voltage originally was 115 volts. When I checked it again, the reading was 126.7 volts. The 12 volt tap on the transformer was 13.1 volt after this. This change in voltage also changed the voltage for all the runs, which in turn ruined the lamps in the five fixtures because all were working at well over 12 volts. All were 20 watt MR-16 BAB's. Not all fixture on each run had bad lamps though. I put a disclaimer in my warranty which protects me from this. I still changed the lamps at no cost this time though. Just thought I would let you know.
02-03-2006, 08:21 AM
What was the cause of the voltage jump?
Frog Lights, LLC
02-03-2006, 08:24 AM
In other countries where our merchandise is sold this is common. Here I would not expect that, perhaps a drop in voltage but not that much of an increase.
02-03-2006, 09:59 AM
Did you have to change taps then?
02-03-2006, 02:34 PM
There are three different power companies here that provide electrical power.
The city provides the power for this property. They do not have an answer for me yet as to why there was an increase in voltage. And yes I had to change voltage taps as well as change transformers. I replaced it with another brand of transformer that had less output at the 12 volt tap and all worked out ok. Luckily the first one I tried worked out ok. It is an FX Luminere that I had lying around still in the box. I will be back to check the system again in a couple of weeks. I spoke with one of my distributors about this and this has happened to some of his customers in Florida. I'm told it is rare though. And by the way, the only bulbs that went bad were MR-16's not any of the G-4 bi-pins.
02-06-2006, 09:41 AM
This is a bigger problem than many realize. I've heard stories from across the nation and especially in Florda talking about line voltages that rise and fall. A big culprit is air conditioning systems that put a massive load on the system. Some installers have found that daytime currents (when AC is on) can be on the low side, then jump 10 to 15 volts at night. The problem is exacerbated when electricians wire GFI outlets into breakers that share other circuits, or when GFI outlets are wired with insufficient gauge. A 10 volt increase in line current causes a 1.0 volt increase on the secondary - that's enough to blow your lamps.
For these reasons, the following measures are suggested:
1. Transformers should have there own dedicated breakers at the panel.
2. Installers should be sure electricians are following code in the installation of the GFI outlet.
3. Installers should check both daytime and nightime line currents to anticipate problems. (This should be done during maintenance visits also).
4. Installers should measure voltage at the fixtures (with all lamps powered on) and set the voltage between 10.8 and 11.2 volts.
Frog Lights, LLC
02-06-2006, 05:57 PM
Your refer to current, don't you mean voltage?
02-07-2006, 02:44 PM
Good catch, yes, I meant to say voltage.
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