Electrician Talk banner
101 - 117 of 117 Posts

·
Registered
Joined
·
28 Posts
All the early K&T and some romex I've seen had a nickel/silvery coating on copper wire. Doubt you could mistake it for aluminum.
A Brief History of Aluminum Wiring

Between 1965 and 1972, approximately 2 million homes were constructed with aluminum wiring.
The wiring that is of major concern is the single strand solid aluminum wiring, connected to the smaller branch circuits supplying receptacles, switches, lights, and appliances such as dishwashers, furnaces, etc. Corrosion of the metals in the connection, particularly the aluminum wire itself, causes increased resistance to the flow of electric current and that resistance causes overheating. Most modern homes have some aluminum wiring, including the main service wires, and the heavier 240 volt circuits that feed other major appliances, such as ranges and air conditioners. The higher voltage wiring does not present the same risk as 15, 20 and 30 amp circuit wiring.


Just as I thought.... Aluminum wire was a much later invention. This was done from 1965 to 1972 when the price of copper was really high. I was guessing it started a little earlier (in the 50's), but I've worked on a number of 60's built homes with it.

In the 70's had an apartment built in the 1890's that had exposed K&T wiring in the garage area, and that indeed had a silvery surface on the wire, almost like it was tinned. And one of my electrician buddies at the time still had the gasoline furnace and crucible for "soldering" the wire together and then used fabric tape to cover the joints. Holding a crucible of molten lead up over your head while dipping the wires into it was pretty crazy. Screw-on wire connectors were a great invention.

We did some of the same stuff with cast-iron plumbing where you would tamp oakum into the joint, then fill it up with molten lead from a little dipper on the furnace, all while laying on your side under the building. PVC and glue is a much better idea.

Mike Sokol
[email protected]
www.noshockzone.org
 

·
Retired Account
Joined
·
39,697 Posts
Just how do you guys deal with "upgrades" to grounded receptacles in old buildings?

Mike Sokol
[email protected]
2 bangers (which they still sell) & gfci's Mike

One of the fundamentals we do on older K&T buildings , much of which exists w/o any grounding, is to introduce it

Myself (as well as others here) usually come off the the MBJ and/or subpanel g-bar with #8 solid

We just bond anything metallic , plumbing, waste lines, furnaces, duct work, etc

This is were the real fun with RPBG and/or even reverse polarity bootleg appliances start becoming more apparent, or at least easier to assess

~CS~
 

·
Retired Account
Joined
·
39,697 Posts
Holding a crucible of molten lead up over your head while dipping the wires into it was pretty crazy. Screw-on wire connectors were a great invention.
I was apprenticed to those guys

They used to run a small forge ,usually in the back of a pu truck, sometimes on the job..... kept a number of irons going while they ran up into attics to do as many joints as a hot one would do

I still have an old iron for porch cha cha

~CS~
 

·
Registered
Joined
·
28 Posts
This is were the real fun with RPBG and/or even reverse polarity bootleg appliances start becoming more apparent, or at least easier to assess
Back in my pile of old guitar amps I have a few with non-polarized or grounded plugs. These have a 200-volt capacitor hooked to a single-pole/double-throw switch which connects the amplifier chassis to either the hot or neutral power wire. It was a 50/50 guess which way was which, and you just switched it back and forth until it buzzed less and shocked you the least. On these old amps the "death cap" as it was called would sometimes short, so now your buzz-switch created a hard bond to the neutral or hot wire. Now it was 50/50 Russian Roulette. Yikes!!!

I also have a very old guitar amp with a non-polarized plug that as AC-DC capable (not the band). Just like an AC-DC tube radio in the old days of Edison DC power, there was no incoming power transformer. One side of the power cord (line or neutral - 50/50 guess) was bonded to the chassis, and the other side went to the string of tube filaments in series that added up to 120-volts. Again, a very dangerous thing which I never bring out of the closet since it could easily kill a visiting guitar player.

I only note this because I have a lot of experience on concert stages where a guitar player is complaining he's feeling a shock from his microphone, when I KNOW the PA system has been properly grounded and checked with an Ambrobe INSP-3, an NCVT and a DMM to the generator ground stake just to be sure. Hey, I take no chances with million dollar clients. In every case I've found an old guitar amp on stage that somebody just picked up at a pawn shop or flea market while on the road. And that's what was creating the shock hazard on the "microphone".

See, it's NOT always the electrician's fault. Sometimes it's the guitar player. ;)

Mike Sokol
 

·
Registered
Joined
·
28 Posts
2 bangers (which they still sell) & gfci's Mike

One of the fundamentals we do on older K&T buildings , much of which exists w/o any grounding, is to introduce it

Myself (as well as others here) usually come off the the MBJ and/or subpanel g-bar with #8 solid

We just bond anything metallic , plumbing, waste lines, furnaces, duct work, etc

This is were the real fun with RPBG and/or even reverse polarity bootleg appliances start becoming more apparent, or at least easier to assess

~CS~
I agree that if you're into K&T wiring, then bonding everything metallic to a new run of #8 is a great idea. I've had the fun of running audio and data cables in really old buildings over the years, and had times when I would get a shock from a piece of pipe or ducting I had assumed was grounded. Those old building wiring systems were death traps for modern electricians doing upgrades.

In an old theater where I did a few sound gigs over the years, the original early 1900's lighting system I saw in the late 70's consisted of a bunch of open copper knife switches on a big wall board. So you were grabbing wooden handles a few inches away from all the live, open copper bus bars that were criss-crossing all over the board. To meet OSHA regs at the time, the theater stage crew built a chicken-wire "safety net" behind the lighting guy so nobody would accidentally push him into all those open bus bars. And to top it off, every neutral bus was also fused with a big cartridge fuse. That's were I learned about troubleshooting open neutrals.

The only thing I read about but never got to see in an old theater was the big wooden pickle barrels of brine water with submerged, electrified bronze plates on a broomstick your lighting crew would move up and down to dim the lights. I guess you didn't want to step in THOSE puddles. :eek:

Mike Sokol
 

·
Retired Account
Joined
·
39,697 Posts
Back in my pile of old guitar amps I have a few with non-polarized or grounded plugs. These have a 200-volt capacitor hooked to a single-pole/double-throw switch which connects the amplifier chassis to either the hot or neutral power wire. It was a 50/50 guess which way was which, and you just switched it back and forth until it buzzed less and shocked you the least. On these old amps the "death cap" as it was called would sometimes short, so now your buzz-switch created a hard bond to the neutral or hot wire. Now it was 50/50 Russian Roulette. Yikes!!!

I also have a very old guitar amp with a non-polarized plug that as AC-DC capable (not the band). Just like an AC-DC tube radio in the old days of Edison DC power, there was no incoming power transformer. One side of the power cord (line or neutral - 50/50 guess) was bonded to the chassis, and the other side went to the string of tube filaments in series that added up to 120-volts. Again, a very dangerous thing which I never bring out of the closet since it could easily kill a visiting guitar player.

I only note this because I have a lot of experience on concert stages where a guitar player is complaining he's feeling a shock from his microphone, when I KNOW the PA system has been properly grounded and checked with an Ambrobe INSP-3, an NCVT and a DMM to the generator ground stake just to be sure. Hey, I take no chances with million dollar clients. In every case I've found an old guitar amp on stage that somebody just picked up at a pawn shop or flea market while on the road. And that's what was creating the shock hazard on the "microphone".

See, it's NOT always the electrician's fault. Sometimes it's the guitar player. ;)

Mike Sokol
I have an old mid 60's SUNN amp, durn thing even has a polarity switch

get it wrong & sparks fly from the mic

the band always blames me! :(

~CS~
 

·
Registered
Joined
·
28 Posts
I have an old mid 60's SUNN amp, durn thing even has a polarity switch

get it wrong & sparks fly from the mic

the band always blames me! :(

~CS~
I'm out of town teaching music production this weekend (my main gig), but if you guys like next week I can draw up a simple diagram that shows all the fault current and ground paths in guitar amps from various decades. Modern music gear passes UL code, but musicians love to play with the old 50's, 60's and 70's gear, and that's where the trouble begins. Those old amps were deathtraps, but can be run safely once you understand the basics.
 

·
Registered
Joined
·
1 Posts
I have fixed a lot of 'bootleg' grounds, working here in WA. Mostly in old houses. It is a good idea to assure there IS a ground system first. On one job, I found a 12ga moldering plumbing bond buried under sheetrock, no gas bond, no ground rod. There were outlets that tested grounded with a 3 light tester. Seems the lesson here is: you can't use a 3 light tester to indicated good ground. I use an Ideal circuit analyzer... it tells me voltage and resistance of each conductor. This makes it much easier to find faults or PARTIAL faults.
 

·
Registered
Joined
·
34 Posts
dspiffy said:
To make things worse, there are some cables in the audio world that have white as hot and black as ground.

In the Telephone/Audio world white is hot (+). It'll mess you up if you're not careful. But I'm not sure that there is a standard you can count on like electrical. And red is usually a hot, while black is not (-).
 

·
Registered
Joined
·
11,094 Posts
Most modern Mac laptops have a convertible power supply. You can slide the 3-wire, 8-ft AC power cord off the supply and replace it with a 2-blade plug that's goes directly into the wall outlet. And yes, the 3-wire grounded cord provides a low-impedance path from the outlet safety ground to the chassis of the laptop. I actually demonstrate this in my NoShockZone seminars as a way to reduce ground-loop hum in sound systems.
How does it do that? Every laptop power supply/charger I've seen whether a 2 wire ungrounded, or 3-wire with ground, (on the line side,) only has a 2-wire output past the electronic switching power supply terminating at a coaxial low voltage connector. In order to have any continuity between the safety (live if reversed polarity connected) ground and the computer, that line side ground would have to be connected to one of the two low voltage output wires. And that just seems insane.
 

·
Registered
Joined
·
34 Posts
five.five-six said:
You have no idea what you are talking about, What's the indication for tip on pair 11? How about for ring on pair 2?

I'm going by what a telephone guy told me. So what is it? You have a white wire and a white wire with a colored stripe. Which is tip, which is ring? Ever punch down a 66 block? There is such a thing as a polarity tester you know.
 

·
Registered
Joined
·
34 Posts
Okay, so I looked it up, just to verify. In a 25 pair cable, white is Tip in the first 5 pairs. Since almost all of the phone work I do is residential, 4-pair is the most I deal with and that goes with what I was told.

In pairs 6-10, red is tip. In 11-15, black is tip. There is a chart for the color code for a 25-pair cable. So I amend my comment to say "in residential phone and audio". I stand corrected.
 
101 - 117 of 117 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top