ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
New fan motor for Panasonic
by HotLine1. 06/25/19 03:53 PM
Burning out of return(white) side of 120volt rec
by crselectric. 06/14/19 02:15 AM
Video door bell causing chime activation of coil
by JoeTestingEngr. 06/13/19 12:43 PM
Troubleshooting Voltage Drop Across Relay
by gfretwell. 06/09/19 11:49 AM
Apple Recalls Three-Prong Wall Plug Adapters
by Admin. 06/05/19 09:06 PM
New in the Gallery:
What is this for?
Plug terminals
Who's Online Now
0 registered members (), 13 guests, and 9 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
What is This? #152516
05/25/05 03:05 PM
05/25/05 03:05 PM
Admin  Offline
OP
Administrator
Member
Joined: Oct 2000
Posts: 3,547
NY, USA
Quote
I had a student bring this in to me today and I'd like to find out what it is. He found it in the attic of a house. The brass piece screws on to cover the part sticking up in the middle. I'm guessing a telegraph relay, but that's just a guess.

Laura Jenkins
Instructor
NECA/IBEW Electrical Training Center
[Linked Image]

[This message has been edited by Webmaster (edited 05-25-2005).]

Tools for Electricians:
Re: What is This? #152517
05/25/05 03:26 PM
05/25/05 03:26 PM
L
Larry Fine  Offline
Member
Joined: Feb 2005
Posts: 693
Richmond, VA
This is a fused lightning arrestor for a telephone line. The cap covers a pair of carbon spark-gaps. The bottom terminal is for ground.


Larry Fine
Fine Electric Co.
fineelectricco.com
Re: What is This? #152518
05/28/05 04:11 PM
05/28/05 04:11 PM
T
techie  Offline
Member
Joined: May 2005
Posts: 247
palo alto, ca usa
The two terminals labeled "L" are for the incoming telephone line, The two labeled "I" are for the telephone instrument, and the terminal labeled "G" is for ground.

Note that the terminal on the upper right is corroded, but none of the others are.
Can anybody explain why that particular terminal would be corroded, but not the opposite side?

Re: What is This? #152519
05/28/05 04:31 PM
05/28/05 04:31 PM
N
NJwirenut  Offline
Member
Joined: Sep 2001
Posts: 806
Bergen County, NJ
Quote
Can anybody explain why that particular terminal would be corroded, but not the opposite side?


That sort of thing is common when DC wiring gets wet. Electrolysis causes one terminal (the cathode, IIRC) to corrode very quickly, while the other electrode is hardly effected.

Re: What is This? #152520
05/28/05 04:32 PM
05/28/05 04:32 PM
P
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Remember that the telephone loop current is DC. That's the same sort of corrosion of one pole that you can see on an automotive battery terminal, or on other DC switching equipment.

Re: What is This? #152521
05/28/05 04:32 PM
05/28/05 04:32 PM
P
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Snap! [Linked Image]

Re: What is This? #152522
05/28/05 06:38 PM
05/28/05 06:38 PM
Alan Belson  Offline
Member
Joined: Mar 2005
Posts: 1,803
Mayenne N. France
Or the French knife switch, posted in PFD.
Alan


Wood work but can't!

Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
sbi
sbi
indiana
Posts: 47
Joined: March 2008
Show All Member Profiles 
Top Posters(30 Days)
Admin 2
Khombo 2
Popular Topics(Views)
255,884 Are you busy
191,858 Re: Forum
181,623 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.020s Queries: 14 (0.004s) Memory: 0.9846 MB (Peak: 1.1372 MB) Zlib enabled. Server Time: 2019-06-27 08:20:45 UTC