Hello;
I have been using surge protection since it was invented, and I paid over $50 for a network quality 6-outlet strip by Newpoint.
These protectors always seem to have an LED labeled "protected when lit", whether they are the run of the mill Staples brand or a more expensive APC model.
I have one from Radio Shack with only one outlet, designed for a large appliance such as a microwave, or AC with electronic controls that can easily be destroyed by a surge.
Recently, I noticed that the green LED that indicates "protected when lit" was not lit, but the appliance was powered and working fine.
I have always suspected that these "protected when lit" indicators were put there for one reason, and it's not to tell you that the protection circuit is working!
The reason they are used, at least in the model I own is so that when the LED burns out, you go out and buy a new protector.
On my Radio Shack unit, screws were used to hold the two halves of the case together, so I took it apart, and proved my theory correct.
The LED that is labeled "protected when lit" is wired through a 24K 1/2 watt resistor directly across the 115V fused line.
The LED has absolutely nothing to do with the fact that the MOV's (there are 3 of them) are working or not.
The only thing the LED could possibly indicate is that the internal fuse has not blown, and that can be found out by testing the appliance plugged into the unit.
The LED in this unit is wired through the 24K resistor directly across the 115VAC line, without a diode. This puts the full 115V on the diode during the reverse phase of the AC cycle (when the LED is not conducting).
In this circuit, it is only a matter of time that the LED will burn out. I am now convinced that the designer chose the LED to sustain the high reverse voltage without breaking down for several years, but no more. This insures that the owner will have to buy a new protection device, and chances are they will buy the same model they had before.
So, to make a long story short, it may be OK to continue to use the surge protector if the "protected when lit" LED is out.
However, it is NOT OK to use the device if the LED indicating a WIRING FAULT is lit. Wiring fault indicates a faulty ground or reversed hot and neutral on the receptacle into which the protection device is plugged. This is a serious problem, and must be repaired immediately.
I hope this saves some of you time and money, but I am also interested to know whether anyone else has taken such a device apart and found the same thing to be true of different types and brands.
FW
I have been using surge protection since it was invented, and I paid over $50 for a network quality 6-outlet strip by Newpoint.
These protectors always seem to have an LED labeled "protected when lit", whether they are the run of the mill Staples brand or a more expensive APC model.
I have one from Radio Shack with only one outlet, designed for a large appliance such as a microwave, or AC with electronic controls that can easily be destroyed by a surge.
Recently, I noticed that the green LED that indicates "protected when lit" was not lit, but the appliance was powered and working fine.
I have always suspected that these "protected when lit" indicators were put there for one reason, and it's not to tell you that the protection circuit is working!
The reason they are used, at least in the model I own is so that when the LED burns out, you go out and buy a new protector.
On my Radio Shack unit, screws were used to hold the two halves of the case together, so I took it apart, and proved my theory correct.
The LED that is labeled "protected when lit" is wired through a 24K 1/2 watt resistor directly across the 115V fused line.
The LED has absolutely nothing to do with the fact that the MOV's (there are 3 of them) are working or not.
The only thing the LED could possibly indicate is that the internal fuse has not blown, and that can be found out by testing the appliance plugged into the unit.
The LED in this unit is wired through the 24K resistor directly across the 115VAC line, without a diode. This puts the full 115V on the diode during the reverse phase of the AC cycle (when the LED is not conducting).
In this circuit, it is only a matter of time that the LED will burn out. I am now convinced that the designer chose the LED to sustain the high reverse voltage without breaking down for several years, but no more. This insures that the owner will have to buy a new protection device, and chances are they will buy the same model they had before.
So, to make a long story short, it may be OK to continue to use the surge protector if the "protected when lit" LED is out.
However, it is NOT OK to use the device if the LED indicating a WIRING FAULT is lit. Wiring fault indicates a faulty ground or reversed hot and neutral on the receptacle into which the protection device is plugged. This is a serious problem, and must be repaired immediately.
I hope this saves some of you time and money, but I am also interested to know whether anyone else has taken such a device apart and found the same thing to be true of different types and brands.
FW