80 year old conduit

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On 8/7/2014 8:03 PM, philo wrote:

You got that dead to rights.
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On 08/07/2014 08:44 AM, dpb wrote:

I don't have time to do any work now...but the coating is cloth covered rubber.
I just got back from Home Depot. I was going to buy some ground clamps...and I ran into the electrician who put in the 200 amp service and told him what I was up to.
He said it is OK to bond around a bad electrical ground...however the mechanical connection should still be good...which it is not...
So I am going to to the right thing and replace all...but not today.
BTW: The ground clamps were more expensive than I figured and all total would cost about the same as Romex and a few junction boxes.
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insulated wire used real gum rubber - which needed to be vulcanized to make it hard - and one of the chemicals used to vulcanize rubber is sulphur - which is very corrosive to copper. The wires were "tinned" before insulating to protect them from the sulphur.
also interesting is the way wire size is measured. Wire is made by drawing it through a series of increasingly smaller dies or “draw-plates” to create its final size. It is believed that wire gauge numbers were originally based on the number of dies that the wire was drawn through. For example, No. 1 was the original rod, and if it was drawn through 12 dies it became 12-gauge wire. If two more dies were added, it became 14-gauge wire, etc. Thus, the larger the gauge number, the larger number of dies it was drawn through, and the smaller the wire. This was the original Brown & Sharpe standard that morphed, more or less, into the American Wire Guage standard used today.
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On 08/06/2014 08:25 PM, snipped-for-privacy@snyder.on.ca wrote:

Very interesting.
I am going to do my best to get the ground circuit down to less than one ohm. If I can't do so, I'm going to rip out the old wiring and re-do the whole mess.
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If you have a raceway system, you should be able to pull out that antique wire and pull in THHN. I would go ahead and pull in a green wire ground and that problem you have becomes less critical.
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On Wed, 06 Aug 2014 22:22:36 -0400, snipped-for-privacy@aol.com wrote:

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On Wed, 06 Aug 2014 22:49:03 -0400, snipped-for-privacy@snyder.on.ca wrote:

Raceway systems are still supposed to be bonded (to ground) but if you have a grounding wire, bonding the raceway is less critical because you are not using it as the fault path to equipment.
You still do not want a "hot" raceway.
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On 08/06/2014 10:49 PM, snipped-for-privacy@aol.com wrote:

If I cannot get this fixed by using clamps and bonding around the hi-resistance areas...and now it seems there are four of them... I am just going to Romex everything. The conduit in the basement is perhaps 25 feet long and from there, a short run of BX goes up to a three outlets at various places along the run.
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On Wed, 06 Aug 2014 23:49:51 -0400, snipped-for-privacy@aol.com wrote:

"Romex" and there is no possibility of a hot raceway. I believe that is still code compliant.
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On 08/07/2014 07:12 AM, snipped-for-privacy@snyder.on.ca wrote:

I am heading off to get some ground clamps now and will try to get all grounds down to less than an ohm.
If that does not fix it, I will have to replace the run.
The boxes have rusted screws and I'd have to chisel them off and re-tap the holes. All the BX feeds have poor grounds too. If I have to replace the BX and the junction boxes, it's going to be easier and better to replace all.
This house only has three original rigid conduit runs and the other two are perfectly OK, so I'm going to leave them alone.
When I bought the house in 1979 it had 30 amp, 115 service.
In 1932 that must have been pretty nice!
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Just to clarify, code does not allow Romex to be run inside conduit, except for short runs for physical protection.
However, it would be a fairly trivial matter to pull out the old wiring and run new THHN wire in the old conduit. You could use the old wires to pull the new wire through.
Of course, if the conduit and boxes are exposed, I would probably take out the old work and run new boxes and cable. By the time you fiddle with stripped conduit and corroded terminals, you could have all new work installed.
Anthony Watson www.mountainsoftware.com www.watsondiy.com
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On 08/07/2014 9:04 AM, HerHusband wrote: ...

That's not _exactly_ right. The tables in the back of the NEC have all the conduit fill info and include how to calculate the area of an elliptical cable and also how to treat a multi-conductor cable as a single conductor for fill calculations and as well as the temperature derating info for the conduit.
The "prohibition" is for NM in conduit without the additional derating for the conduit required, but that isn't blanket exclusion entirely.
That said, the difficulties in pulling NM instead of single THHN runs makes it such that one would choose the latter in almost all cases, anyway.
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iron core wire. If it was wired for 48 volts DC there was no enforced code at the time. There has never been an "approved" branch circuit conductor made of iron in Canada or the USA. It is used extensively in power distribution, and in copper clad form, in RF distribution where skin effect makes copper clad wire just as good as solid copper - with higher tensile strength and lower cost. It has also been used for telephone distribution cable.
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On 08/07/2014 11:39 AM, snipped-for-privacy@snyder.on.ca wrote: ...

The original locations were DC, yes, but I'm not sure of all of what might have been available options in the early 30s when the farrowing house was built/wired. It did predate REA reaching us by quite a long period, though, as that didn't happen until '48 (folks began collecting petition/formation signatures in early '45 before V-J day and the co-op was formed very shortly after the end of the war but it took almost 3 years to reach us with the lines towards the west end of their service area and Dad was on board from its originizational meeting for 50 yr).

Well, while that may well be true, that philo has what seems to be the same material as here shows it wasn't at least unheard of for there to be something other than Cu in the time frame that seems to coincide with that of this here.
I asked at the coffee shop this morning if any of the other old codgers had any recollection -- one fella' suggested the core might be nickel-silver (or "german silver")...would meet the indications of the observed visual characteristics. I'll have to do some more serious digging around and see if can't find a spare chunk to do actual 'spearmints with which...
--


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On 08/07/2014 12:27 PM, dpb wrote:

...
While the main house and barn, etc., were wired and ran on the Delco, grandfather was thinking ahead and the wiring was done with eventual power in mind. All that needed changeout when connected to REA was the DC switches (of which I still have a half-bushel basket full of the push-button Victorian-era mother-of-pearl buttons for those who are in dire need of same. :) )
Was interesting when still doing coal analyzer support for Sask Power there're still enough farmsteads there that there was a co-op store in Weyburn with DC appliances on their showroom floor (as recently as about '95, anyway).
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On 08/07/2014 2:57 PM, dpb wrote:

And, just to clarify we're not totally still in the dark ages, the folks essentially gutted the house in the late '70s before moving from our "little house" next door. All new plumbing/wiring/insulation added/etc./etc./etc., ... then.
Most all the main outbuildings were drastically upgraded in the 60s after Dad took over the operation from grandfather and we added quite a lot more ground and larger cattle operations to get with the changing times and particularly after the 50s drought broke there were some good years that allowed for some investment. So, other than just these few locations like the aforementioned garages, the old shop, the farrowing house (now totally unused except for storage), etc., that have nothing more than lighting circuits for a few overhead bulbs and (maybe) an outlet or two, it's all pretty much up to what was Code at that time...I've never worried about much of the newer Code changes as never could see any real need as was discussed in an earlier thread.
--


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On Thu, 07 Aug 2014 08:12:39 -0400, snipped-for-privacy@snyder.on.ca wrote:

The raceway itself is still supposed to be bonded. This is normally handled by the connectors into the bonded(grounded) boxes.
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On Thu, 7 Aug 2014 14:04:57 +0000 (UTC), HerHusband

That is a common misconception but not true. The biggest problem with Romex in conduit is "fill:" You have to compute it as a conductor the size of the widest dimension. It is also pretty hard to pull. (no nylon jacket like THHN)
I think Philo was talking about abandoning the conduit altogether tho.
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derating is by conductor count (and a few other factors). The fact that it is a cable in a raceway does not change that.
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On 08/07/2014 12:53 PM, snipped-for-privacy@aol.com wrote:

I was thinking I remembered the temperature-rating tables were based on conduit or no, as well, though??? I didn't recheck the recollection though, granted.
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