Took the junction box apart and disconnected the wires.
Cleaned them well and saw that they are pure copper...the "steel" color
was due to tarnish and also the tinning from being soldered.
The threads on one pipe were stripped so I decided to just sand them to
bare metal and slip a 3/4" EMT conduit connector onto it. The connector
was slightly large for the pipe so I made a sleeve from a short section
of 3/4" conduit.
Punched a larger hole in the box to match the fitting and put it all
back together. Then put bonding grounds on the three BX sections and got
my ohm meter out.
Now I have the resistance down to about 0.3 OHM and a good mechanical
connection at the junction box.
Well, there is one place that has a junction box that can reach w/o a
ladder so I 'splored some--w/o disconnecting anything, I have convinced
myself it is _not_ ferromagnetic via the magnet test. So, I think it's
confirmed it is _not_ steel core; what it is, actually, I don't know.
I'll try to do some more digging thru the loft next time I'm up there --
there's almost bound to be a remnant or two but it could be buried
On Thu, 07 Aug 2014 15:06:27 -0400, firstname.lastname@example.org wrote:
It is quite possible the entire conductor was tinned - As I noted in
an earlier post, sulphur used in the vulcanizationof early rubber
insulation was hell on bare copper, so many wires were tinned full
length before insulating. Made it a lot nicer to solder, too.
Pre-tinned copper is a BREEZE to solder
It is most likely hard drawn copper. I had some feeding a house as the
main. It was an old house so the wire was not at all very thick - maybe 10
gauge (probably a 30 or 40 amp main!) and it was really tough to cut.
That's the point; it is _not_ Cu--a freshly cut end face reveals that it
is copper-plated with a silverish colored interior. It isn't
particularly hard nor stiff--of course, it's only 12 ga. Anyway, it's
not copper-colored; can't say it's not some alloy but I've no klew as to
what. If and when I find a chunk I'll clean up an end and try to get a
magnified end picture that shows the face...
Been a couple years now since I added that switch in the garage so
memories are a little fading but I don't recall making the connections
being difficult to work with just the peculiarity of the look when one
clips off the ends of the old joints to make a new connection.
I had a thought in passing that it might have been some wire provided by
the REC when they were new but think that can't be right either as this
surely predated their existence being as the old farrowing house is
wired with it, too...and it was almost new in the early '30s from which
have an entry form granddad filled out for a Farm Bureau "Operation
Enhancement" annual award from which can tell he was obviously pleased
as punch with it... :)
The basic derating rule is here
Table 310.15(B)(2)(a) Adjustment Factors for More Than Three
in a Raceway or Cable
Number of conductors and derating factor
41 and above 35%
Then you go to the derating adder for ambient temperature at the
bottom of 310.16
They also derate for raceways on roofs exposed to sunlight and cables
penetrating top plates through insulation. (basically do not bundle a
bunch of cables in the same hole)
You do not have to derate a nipple less than 24"
Because of the limitations of 240-4(D) (the 14 ga -= 15a, 12ga = 20a
rule) when you are using THHN you really do not end up derating until
you are over 9 conductors in most cases. You derate from 310.16 90c
column. Those numbers are high enough that 70% is still within the
High ambients and rooftops can get you though.
On 08/07/2014 6:41 PM, email@example.com wrote:
Granted for a practical case of this magnitude it's generally not an
issue becase most of the old lower temp-rated styles are no longer
around so one doesn't run into the limitation since the higher-rated
wire covers the situations.
I was thinking simply of the generality of the overall process...not a
specific case and shouldn't have use TH in the wording owing to it being
higher-rated and therefore immune.
We are already getting pretty pedantic but "TH" is not enough.
You really need to see "xHHx"
THWN is a 75c conductor and dual rated THHN/THWN when used in a wet
location is now 75c too.
Silly, maybe but that is what the code says.
I have pulled romex through short runs of conduit but they were generally
under 5' long and straight. Pulling stiff cable through bends would be very
Now that I finally have all the wiring done I decided to check one last
The electrician put in two new 8' ground rods, he said a total of 16' of
ground is the new requirement.
All that was left on the old ground rod was my telephone/internet
I decided to see how good the original ground was and got a rather poor
connection. Nearly 600 ohms between the two grounds!
I decided I better tie the old rod into the new one.
On Friday, August 15, 2014 9:52:20 AM UTC-4, philo wrote:
They can't be left unconnected. The ground for the telephone,
internet (cable?), must be the same grounding system that is used
for the service. They can't be on their own separate ground. Back
in the day, that was allowed. But not today and since he changed
the grounding system, that is now a requirement.
Well, to be on the safe side I have them all tied together now.
The new ground rods are located in the dampest possible part of my
property. Since the old one had a resistance of 600 ohms, I suppose it
could have been argued that it was not really a ground at all.
I also have an unused phone line that was there back when I had
dial-up...I decided to connect that to the ground rod also.
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