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#152913 - 03/02/06 09:51 PM Another wierd item  
Trumpy  Offline

Joined: Jul 2002
Posts: 8,217
SI,New Zealand
Pictures and info supplied by napervillesoundtech:

This was found in an old wiring closet in a school. It was very dusty, and had a large box of papers on top of it; hence the broken light bulb parts in the sockets. It is about 5 feet long, and has a 25 amp fuse, although a 15 amp plug and a 16 gauge power cord. The wire is 14 gauge solid white. I have not plugged this in (and I won’t), but, it seems like this is supposed to teach the differences of series/parallel or something. I assume that you would have to adjust the switches with the power off, seeing as though there is very little insulation. One switch has an entirely metal knife and a partly broken porcelain base. It seems like these parts were meant for low-voltage use, and just got stuck on here. I shudder to think of a time when this would have been part of school curriculum.

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Thanks Ben. [Linked Image]

[This message has been edited by Trumpy (edited 10-21-2006).]

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#152914 - 03/03/06 12:36 AM Re: Another wierd item  
yaktx  Offline
Joined: Feb 2003
Posts: 288
Austin, Texas, USA

I too shudder to think that this may once have been part of a school curriculum, but such parts were once common. Well into the '20s and possibly even later, knife switches were standard for service equipment, and cleat lampholders such as those shown here were in common use.

Even today, the NEC allows cleat lampholders with exposed live parts, if they are located a minimum of 8' above the floor! Needless to say, I would never install one.

And those single-pole knife switches? I visited a church in Mexico in 2001 that had those for lighting, in public areas, at customary wall-switch height! [Linked Image]

#152915 - 03/03/06 01:54 PM Re: Another wierd item  
napervillesoundtech  Offline
Joined: Feb 2006
Posts: 144
Naperville, IL, USA
Some of the switches are single pole, the "main" switch is a double, switching both the hot and the neutral. This has one of those old, non-deadfront type rubber plugs on it, which is not polarized. I agree, I wouldn't want to install one of those lampholders, either. They are also hard to find in stores, I have noticed, although I have never tried to order them from a supply company.

#152916 - 03/03/06 02:32 PM Re: Another wierd item  
SvenNYC  Offline
Joined: Aug 2002
Posts: 1,691
New York City
I've bought a few from Home Depot and/or Lowes; but they only sell the plastic types.

I've seen the porcelain varieties in lamp-parts stores and independent small hardware shops too.

Knife switches, while still common, are now these little plastic things, about half the size of that. Another easily found item.

#152917 - 03/03/06 11:27 PM Re: Another wierd item  
JoeTestingEngr  Offline
Joined: Nov 2005
Posts: 785
Chicago, Il.
Consider the possibility that this might have been used as a crude load bank for who knows what. You could use something like that to check regulation on a LVPS, for example.

#152918 - 03/04/06 12:47 AM Re: Another wierd item  
RODALCO  Offline
Joined: Dec 2005
Posts: 854
Titirangi, Akld, New Zealand
Quite possible it was used as a series load bank.
I use 2 x 100 watt lamps parallel in series with an appliance under test, especially for radio's, tapedecks and the like to have a limiter in case of a dead short at a faulty appliance.
I take one lamp out depending upon VA rating of appliance under test.
I like to see the porcelain fittings, a lot more durable then the plactic c%@p we get now these days.

The product of rotation, excitation and flux produces electricty.

#152919 - 03/04/06 03:09 PM Re: Another wierd item  
mxslick  Offline
Joined: Oct 2004
Posts: 803
Atomic City, ID USA
I shudder to think of a time when this would have been part of school curriculum.

I don't. In the era that this device would have been found in use, both adults and kids had more common sense and maturity. It would have been a very effective demonstration of the principles of current flow and what-not.

I have always been a "tactile" type. Show me a schematic, and I can work it through with some difficulty. Show me the actual device first, then I can not only read through the schematic a lot faster, I can draw one up!

Or a better example, I designed a dual-motor control with delay start for motor #2 for pipe organ blowers. I built it first, then drew out the diagram by hand after in about an hour. It would have never gotten built if I'd tried to draw it up first.

I flunked chemistry in High school for the same reason. Give me the chemicals and lab supplies and I could solve any formula. Give me the book or a list on paper, I couldn't get the formulas right to save my life! Really ticked off the teacher and my parents!

Stupid should be painful.

#152920 - 03/04/06 09:30 PM Re: Another wierd item  
JoeTestingEngr  Offline
Joined: Nov 2005
Posts: 785
Chicago, Il.
I guess this a little off topic but concerns how people think about things. Several years ago I was sent a file named "brain.exe" You answer a series of questions and it performs an analysis. Everyone at work gave it a shot and found it to be interesting. If anyone wants to check it out, email me and I will attach it to a reply.

#152921 - 03/04/06 10:58 PM Re: Another wierd item  
napervillesoundtech  Offline
Joined: Feb 2006
Posts: 144
Naperville, IL, USA
You all bring up a good point I hadn't thought of. Assuming that you are cautiouss and do not touch any live parts, this wouldn't be that bad. I am mostly thinking of people I went to school with who would grab part of it "just to see what would happen" An electronics/electrical class can be very scary sometimes. [Linked Image]

#152922 - 03/05/06 05:21 PM Re: Another wierd item  
Texas_Ranger  Offline
Joined: Dec 2001
Posts: 2,399
Vienna, Austria
I imagine something like that being on a teacher's desk, with the students watching from some ten feet away.

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