I will pick up my 1968 A/S 28 ft Internationsl soon, for full time use, with municipal electric service hookup. I want to check the efficacy of the "original wiring". Even though the lights turn on with the switch, I want to check for potential shorts, degraded connections, etc. Is the wiring relatively accessible without tearing the whole rig apart? Thanks in advance for the advice. Joe Bell joebell4@yahoo.com
Check wiring
- Thread starter joebell4
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s.harrington
Senior Member
Check wiring
All you should worry about is a possible voltage leak to ground through the body of the rig. Unplug your rig from shore power and do an ohms check between the power leg and the ouside of the rig and also between the neutral and the outside of the rig. Both should read infinity or on a digital meter OL. ( If it has the old style wiring however your ground and neutral will be on the same leg and will show very little resistance.) With old wiring as the insulation breaks down you can get leakage without it showing up as a short.
All you should worry about is a possible voltage leak to ground through the body of the rig. Unplug your rig from shore power and do an ohms check between the power leg and the ouside of the rig and also between the neutral and the outside of the rig. Both should read infinity or on a digital meter OL. ( If it has the old style wiring however your ground and neutral will be on the same leg and will show very little resistance.) With old wiring as the insulation breaks down you can get leakage without it showing up as a short.
Check wiring
A good test of the condition of electrical wiring is to "Megger" each run of wire. Electricans or RV techs are sources for these devices which place a high voltage on each wire. The voltage is selectable, but considering the age of you unit I would suggest testing at 500V. Most wire used for wiring power circuits is insulated for 600V. A rule-of-thumb for testing insulation is twice the rated insulated rating (2 x 600) plus 1000V = 2200V. You would be significantly under this value (which is used to confirm the integrity of new installations). Using the 9V battery used in most volt-ohm-meters as the source for the test voltage would reveal little info on the condition of your wiring.
Good Luck
A good test of the condition of electrical wiring is to "Megger" each run of wire. Electricans or RV techs are sources for these devices which place a high voltage on each wire. The voltage is selectable, but considering the age of you unit I would suggest testing at 500V. Most wire used for wiring power circuits is insulated for 600V. A rule-of-thumb for testing insulation is twice the rated insulated rating (2 x 600) plus 1000V = 2200V. You would be significantly under this value (which is used to confirm the integrity of new installations). Using the 9V battery used in most volt-ohm-meters as the source for the test voltage would reveal little info on the condition of your wiring.
Good Luck
Kirk
Senior Member
Check wiring
While I agree with Homeroid about the use of a "meger", which is just a device to test circuits for resistance to ground at a high voltage that also reads out in the meg-ohm ranges, I doubt that you are very likely to find a place to borrow one. It was a very common piece of test equipment when I was in the Navy, but I have seldom seen one since. It would be a good test, if you can locate the equipment.
On a 1968, you may very well have some 120V-ac lights as well as the 12V ones. The most likely place for there to be a problem at the connection points. If you use a quality multimeter and check from each wire to ground, you can do a lot. But, if you are working on 12V systems, they all use a chassis ground so all that you will read is the resistance of the lights unless you first remove all bulbs from the 12V lights. I would start by making sure that all electrical connections are good and tight. Open your 120V-ac power distribution panel and check every connection. Do the same for all of the places that you have connections on any electrical equipment. Be alert for any signs that wires have rubbed against something. If you wish, it would not be a bad thing to remove all of the lights and check the connections to them. I would do the same in any electric item that is outside in the weather. If you see signs of corrosion in the places where the wires are connected or in terminal boxes that is a warning. If all connections seem to be clean and tight and all leads to ground read in the kilo-ohm range with the connection open, then all is probably fine.
While I agree with Homeroid about the use of a "meger", which is just a device to test circuits for resistance to ground at a high voltage that also reads out in the meg-ohm ranges, I doubt that you are very likely to find a place to borrow one. It was a very common piece of test equipment when I was in the Navy, but I have seldom seen one since. It would be a good test, if you can locate the equipment.
On a 1968, you may very well have some 120V-ac lights as well as the 12V ones. The most likely place for there to be a problem at the connection points. If you use a quality multimeter and check from each wire to ground, you can do a lot. But, if you are working on 12V systems, they all use a chassis ground so all that you will read is the resistance of the lights unless you first remove all bulbs from the 12V lights. I would start by making sure that all electrical connections are good and tight. Open your 120V-ac power distribution panel and check every connection. Do the same for all of the places that you have connections on any electrical equipment. Be alert for any signs that wires have rubbed against something. If you wish, it would not be a bad thing to remove all of the lights and check the connections to them. I would do the same in any electric item that is outside in the weather. If you see signs of corrosion in the places where the wires are connected or in terminal boxes that is a warning. If all connections seem to be clean and tight and all leads to ground read in the kilo-ohm range with the connection open, then all is probably fine.