Timeline for Checking house wiring for high resistance connections
Current License: CC BY-SA 3.0
9 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Nov 18, 2016 at 14:14 | comment | added | Ed Beal | Generally 12 & 10 Al awg wire is rated the same as 14 &12. When the home was wired the type of wire (the specific type or alloy of aluminum) did not hold up as well as today's mix. I will only Use aluminum for feeders on loads that are consistent and never come close to 80% of the rated value because of problems back in the 70's and problems with motor loads burning off the ends on larger high amperage motors. but I have read that the newer alloys are much better. | |
| Nov 18, 2016 at 1:53 | comment | added | Jim Stewart | At the time this house was built #12 AL and #10 AL were claimed to be equivalent, respectively, to #14 CU and #12 CU. I think that is no longer accepted. | |
| Nov 18, 2016 at 1:47 | comment | added | Jim Stewart | I went to the Southwire voltage drop calculator (southwire.com/support/voltage-drop-calculator.htm) and it states that in the current NEC #12 aluminum cannot be used to carry 13 A! They recommend #8 AL for an 80 ft run to give 2 % drop for 13 A. However, the calculator shows that #14 copper can be used for 15 A circuits and would have 3% drop over 52 ft. This circuit in my house with the 10 V drop is explainable by resistance of the wire itself. I will still test the drop at each receptacle while pulling 13 A at the farthest one.. | |
| Nov 17, 2016 at 23:36 | comment | added | Ed Beal | Wow 10v drop is huge in residential wiring over 2x the code requirement. I would leave the load in place at the furthest outlet and check each one to see if they are all dropping some voltage or if you find one that drops a few volts and tackle the worst ones first. Anything more than a few 1/10's of a volt should be cleaned and anti oxide compound applied prior to a new aluminum rated wire nut at the splice. | |
| Nov 17, 2016 at 22:10 | comment | added | Jim Stewart | There is inaccuracy in determining the length of wire in the 15-A circuit which is showing the 10 V drop when carrying 13 A. There are 8 receptacles and one closet light (at the end) on that circuit in three different bedrooms! I might find that the length of wire is more like 100 ft. I could open up each one in turn moving from closest to farthest from the panel and check each one by stabbing through the insulation or just redo the splices with the AlumiConn connectors. | |
| Nov 17, 2016 at 14:45 | comment | added | Carl Witthoft | I agree w/ Ed that you're unlikely to achieve the measurement accuracy required. | |
| Nov 17, 2016 at 14:15 | comment | added | Jim Stewart | OK so the formula and constants in the answer above gives for the resistance per foot of aluminum house wiring is: 12 AWG 0.0065 ohm/ft and 10 AWG 0.0041 ohm/ft. | |
| Nov 17, 2016 at 4:36 | comment | added | Jim Stewart | Assuming the unit of L is in ft, the voltage drop in 50 ft of 12 AWG solid AL carrying 13 A would be 2 (21.2)(13 )(50)/6530 = 4 V. I see 10 V drop in a circuit which I could estimate as 50 ft. I guess I will check this circuit. | |
| Nov 17, 2016 at 0:35 | history | answered | Ed Beal | CC BY-SA 3.0 |