Andrew Shadow
Site Supporter
In another thread that @Flapajack resolved this morning he mentioned that the initial test that her performed to check his fuses indicated that they were all good when one fuse actually was not.
So as not to muddle the content of his thread I started this one to ask something that comes to mind every time that I use my 12 V incandescent test light.
In his thread he did not mention whether or not he had used a multi-meter to test the fuses the first time or if he had used a test light. I will take this opportunity to make the point that in my opinion using a test light is a far better option than using a multi-meter to test live circuits. Multi-meters are good for testing how much resistance there is in a circuit but not very good for testing if there is a good solid circuit when performing a simple voltage check. Multi-meters need an almost insignificant amount of current flow to register that there is 12 volts present. Having 12 volts present does not mean that there is good enough conductivity to allow enough current flow to actually operate the electrical device that is downstream of the test point. If a multi-meter is going to be used a more accurate indication might be attained by checking for voltage drop as opposed to merely checking for the presence of voltage. A test light is much simpler and easier to use than doing voltage drop tests for basic circuit testing. A test light adds a load, as small as it is, to the circuit. This small load more often than not will cause the test light to burn dimly, or very dimly, if there is a connection but it is a bad connection with excessive resistance. This gives a good visual indication that not all is right with what is being tested.
Whenever I test electrical circuits the first thing that I do is connect my test light directly to the battery for two reasons. One is to make sure that the test light is working. The second is that it gives me a fresh visualization of how brightly the bulb burns when it is connected to a full 12 V and is not encumbered by excessive resistance. Having this fresh picture in my mind allows for easy recognition of when it is dimmer when testing elsewhere. If it is dimmer there is a reason for that.
So below is my question for @SMSW and @Larry Fine, and any other electrical experts on here.
I still have a typical old school 12 V test light that has an incandescent bulb. It has proven pretty helpful for indicating when there is a problem in a circuit because it will illuminate more dimly as explained above. I recently thought that I had lost it and was going to buy a new test light. Most of the new ones have LED bulbs in them. LED bulbs require an extremely small amount of current flow to make them illuminate, and I assume that they do not place as much of a load on the circuit as an incandescent test light does. This made me wonder if they would react the same way that a multi-meter does in that they would indicate the presence of 12 volts but not provide an indication that there may be excessive resistance in the circuit being tested. Most LED's either come on or they don't. Maybe I have that wrong and LED test lights do vary their intensity based on the current flow. I don't know as I have never used an LED test light. If they do simply either illuminate or don't illuminate I would prefer an incandescent bulb test light. Because I didn't know I was going to look to buy another test light that has an incandescent bulb.
P.S.
I found my test light and didn't have to buy a new one, so I never had to figure this out but I am still curious about it.
So as not to muddle the content of his thread I started this one to ask something that comes to mind every time that I use my 12 V incandescent test light.
In his thread he did not mention whether or not he had used a multi-meter to test the fuses the first time or if he had used a test light. I will take this opportunity to make the point that in my opinion using a test light is a far better option than using a multi-meter to test live circuits. Multi-meters are good for testing how much resistance there is in a circuit but not very good for testing if there is a good solid circuit when performing a simple voltage check. Multi-meters need an almost insignificant amount of current flow to register that there is 12 volts present. Having 12 volts present does not mean that there is good enough conductivity to allow enough current flow to actually operate the electrical device that is downstream of the test point. If a multi-meter is going to be used a more accurate indication might be attained by checking for voltage drop as opposed to merely checking for the presence of voltage. A test light is much simpler and easier to use than doing voltage drop tests for basic circuit testing. A test light adds a load, as small as it is, to the circuit. This small load more often than not will cause the test light to burn dimly, or very dimly, if there is a connection but it is a bad connection with excessive resistance. This gives a good visual indication that not all is right with what is being tested.
Whenever I test electrical circuits the first thing that I do is connect my test light directly to the battery for two reasons. One is to make sure that the test light is working. The second is that it gives me a fresh visualization of how brightly the bulb burns when it is connected to a full 12 V and is not encumbered by excessive resistance. Having this fresh picture in my mind allows for easy recognition of when it is dimmer when testing elsewhere. If it is dimmer there is a reason for that.
So below is my question for @SMSW and @Larry Fine, and any other electrical experts on here.
I still have a typical old school 12 V test light that has an incandescent bulb. It has proven pretty helpful for indicating when there is a problem in a circuit because it will illuminate more dimly as explained above. I recently thought that I had lost it and was going to buy a new test light. Most of the new ones have LED bulbs in them. LED bulbs require an extremely small amount of current flow to make them illuminate, and I assume that they do not place as much of a load on the circuit as an incandescent test light does. This made me wonder if they would react the same way that a multi-meter does in that they would indicate the presence of 12 volts but not provide an indication that there may be excessive resistance in the circuit being tested. Most LED's either come on or they don't. Maybe I have that wrong and LED test lights do vary their intensity based on the current flow. I don't know as I have never used an LED test light. If they do simply either illuminate or don't illuminate I would prefer an incandescent bulb test light. Because I didn't know I was going to look to buy another test light that has an incandescent bulb.
P.S.
I found my test light and didn't have to buy a new one, so I never had to figure this out but I am still curious about it.
