Electrical

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# Photocell Problems

## What is a photocell?

A photocell is essentially a resistor where the resistance decreases as the incident light intensity increases. It has the nature to exhibit photosensitivity. The other terms or references for a photocell are photo-resistors or light dependent resistors (LDRs).

To know about photocell troubleshooting in particular, below are a few questions answered by Experts.

## While attempting to wire a photocell to three 100 watt lights why does the photocell only turn off the light it is connected to but not the other two?

This may be case of incorrect wiring. To address this issue of the photocell working only on one light rather than all three, the following checks or change is needed to be made to the wiring. The black wire from the power line should be connected to the black wire of the photocell. Next the black wire from the light and the black wire exiting the other fixtures should be connected to the red wire. Subsequently it should be ensured all the white wires are connected to each other and this should overcome the photocell problem being experienced.

## A new photocell was connected by cutting an outdoor electrical cord during daylight hours when it is plugged into, the lights blink every 14 seconds, but during the night they remain on continuously. Why is this happening?

A proper or correct connection is when the photocell black is wired to the GFCI side of the black cord and red to light side of black. In case the lighting load is equal to or less than the maximum load of the photocell, one of the main possibilities is that the photocell is defective. c

## What could cause a old photocell that was replaced with a new photocell where there is one black, one red and one white in the box with similar wiring on the photocell not work?

Basically the circuit black wire should connect to the black wire of the photocell, the whites from the house, photocell and fixtures all connect together. Finally the red should connect to the black from the lamps.

## In order to connect a photocell and LED light (for indoor use) which requires 1,500 hours, what is the smallest size battery required and how many of them need to be used?

Normally a typical LED is in this type of an application requires approximately 0.5 watts. This implies that at 4.5 volts it is drawing approximately 0.11 amps. In order to operate it for 1,500 hours a battery capable of 165 amp hours (1500 x 0.11) is needed. This is equivalent to three car batteries. Additionally car batteries are 12 volts and there may be a need to find a way to reduce the available voltage. In order to reduce voltage, any of the following components may be required: a power supply, another solid state electronic device, 4.5 volt batteries or three LED lights in a series so that it is a cumulative of 13.5 volts.

## What are the main instructions which pertain to a photocell controlled outdoor timer? (Model 15112)

Some of the main instructions pertaining to the photocell controlled outdoor timer are:

1. The timer should be plugged into a GCFI outlet, especially while being used outdoors. The GFCI receptacle should be mounted on an approved outlet box which is protected from severe weather changes or is weather proof.

2. Functions can be selected by rotating the selector dial. They are as follows: Power on/off, 2, 4, 6, or 8 hours “On” at dusk. “Off” (2), (4), (6) or (8) hours later, Dusk-Dawn – “On” at dusk and “Off” at dawn. To activate the “Dusk/Dawn” feature, the timer should be mounted in such a manner where it can experience the changes from dusk to dawn

3. This photocell controlled outdoor timer is not a permanent installation and should not be used for longer than a 90 day period per year.

4. While it is being used outdoors, it is mandatory be plugged into GFCI

Photocells are unique components which is can be intrinsic or external. Listed above are a few photocell problems or questions which have been experienced. The value of Expert information in this regard has been useful and necessary as well. Hence to ask more photocell questions and obtain answers to photocell problems, Experts can be contacted. They will provide the answers in a simple and efficient manner.

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