The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
Calling all Non-US members!! (Non-US only)
by aussie240
Today at 02:39 AM
Photo Upload Tutorial
by DanK
Yesterday at 11:35 PM
Sprinklered equipment 26-008
by bigpapa
12/02/16 04:24 PM
On Delay Relay with Auto Reset
by Potseal
12/01/16 09:59 AM
Wow, that was close!
by jraef
11/28/16 07:06 PM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 13
HotLine1 9
Texas_Ranger 8
sparkyinak 7
Trumpy 6
Who's Online
1 registered (LongRunner), 218 Guests and 5 Spiders online.
Key: Admin, Global Mod, Mod
Page 1 of 3 1 2 3 >
Topic Options
Rate This Topic
#5196 - 11/07/01 04:58 PM Dry Contacts
Frank Cinker Offline
Member

Registered: 07/29/01
Posts: 317
Loc: Pennsylvania
I've often heard fire alarm technicians use the term "dry contacts". At the risk of posting a dumb question I ask what are dry contacts.

Top
Work Gear for Electricians and the Trades

Work Gear for Electricians and the Trades
Work Gear for Electricians and the Trades
Arc Flash Clothing, Gloves, KneePads, Tool Belts, Pouches, Tool Carriers, etc. etc....

#5197 - 11/07/01 05:09 PM Re: Dry Contacts
sparky66wv Offline
Member

Registered: 11/17/00
Posts: 2339
Loc: West Virginia
Didn't use saline before you put them in your eyes?

Sorry, couldn't resist...

Dunno... An askeral (grease, noalox) to help prevent arcing?

Got me...
_________________________
-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI

Top
#5198 - 11/07/01 05:36 PM Re: Dry Contacts
sparky Offline
Member

Registered: 10/18/00
Posts: 5545
Frank,
they are a set of N.O. or N.C. contacts that are not energized, therrfor the term 'dry'

yaknow, if someone published a book of 'trade slang' i'd buy it


Top
#5199 - 11/07/01 07:16 PM Re: Dry Contacts
Bill Addiss Offline
Member

Registered: 10/07/00
Posts: 4196
Loc: NY, USA
Sparky,

Got something close;

Dictionary of Comstruction Terms

Bill

Top
#5200 - 11/07/01 07:52 PM Re: Dry Contacts
wolfdog Offline
Member

Registered: 10/24/01
Posts: 135
Loc: Dallas,TX
I understood they were very low resistance contacts-like gold plated. I have run across
that requirement for alarm circuits in a/c units before. An official ruling would be helpful.

Top
#5201 - 11/07/01 07:53 PM Re: Dry Contacts
NJwirenut Offline
Member

Registered: 09/15/01
Posts: 816
Loc: Bergen County, NJ
"Dry Contacts" refer to a set of electrical contacts that switch such low voltage/current that there is no "self-cleaning" effect caused by arcing/sparking during operation.

Contacts used in such applications should be made of precious metals (gold, rhodium, platinum, etc.) to ensure reliable operation, especially in a corrosive atmosphere where an insulating film might build up.

Top
#5202 - 11/07/01 07:59 PM Re: Dry Contacts
electure Offline

Member

Registered: 12/24/00
Posts: 4226
Loc: Fullerton, CA USA
Well, let's see. A mercury switch is a "wet contact", so...
A "dry contact" is the one all of us are accustomed to seeing, with contact points.
The wet contacts don't wear out like the dry ones, and unless I'm wrong (as usual), are capable of carrying higher current for their relative size.
Scott 35, are you around?

Top
#5203 - 11/08/01 04:10 AM Re: Dry Contacts
Redsy Offline
Member

Registered: 03/28/01
Posts: 2138
Loc: Bucks County PA
I would say any set of "field contacts", such as those that are part of a pressure, or flow switch assembly that do not contain an internal power source.

Top
#5204 - 11/08/01 05:54 AM Re: Dry Contacts
JBD Offline
Member

Registered: 07/12/01
Posts: 599
Loc: WI, USA
The terms dry and wetted have nothing to do with the physical construction of the contacts.

A dry contact is a contact that receives power from a source. Examples include:
Thermostats, Pushbuttons, Doorbell buttons, relay contacts, door switches, and even standard light switches.

A wetted contact is a contact that provides power to a load. Examples include:
Time clock switches, Commercial float/pressure switches, and most low voltage solid state controls.

Top
#5205 - 11/08/01 06:28 AM Re: Dry Contacts
electure Offline

Member

Registered: 12/24/00
Posts: 4226
Loc: Fullerton, CA USA
I'm missing the boat here in a big way.
Not to be sarcastic or disrespectful but:
All contacts receive power from a source.
No contact makes its own power.
All contacts supply power to a load.
The examples given by JBD could be reversed, and it would still seem to make just as much sense to me...none.
(I'm looking around the house for my dunce cap)

Top
Page 1 of 3 1 2 3 >



ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals