Spade lugs vs plain wire for control panel connections

[pstemari]

I'm hooking up some industrial push buttons (Omron A22R series, datasheet, Digikey), and wondering if it's a best practice to use spade lugs or just put the wire ends in the connection clamps directly.

Advantage of the plain wire is convenience and compactness.  Spade lugs (properly crimped) have a better grip on the wire, but they are a tight squeeze in the box.  Unfortunately the datasheet doesn't provide a clear preference, just that both are OK.

Application here is a motor control for a 12" metal lathe.  The start, stop, and lock switches are controlling a 120VAC relay that provides power to the motor.

[tautech]

Only use insulated lugs for mains especially if you are tight for room.
Screw terminal termination will be perfectly OK and probably be less cramped for room when done.

[Paul Moir]

Third possibility not represented are wire ferrules.

Once you start using them, you'll never use bare wire again unless the screw terminal is incompatible with them somehow.

[LabSpokane]

Third possibility not represented are wire ferrules.

Once you start using them, you'll never use bare wire again unless the screw terminal is incompatible with them somehow.

+1

These will go a long way to preventing wires coming loose. Otherwise, be sure to go back and re-torque the connections after letting the panel sit for a day. If you're going to do a lot of this kind of work buy yourself a set of Wiha insulated drivers. They will allow you to properly torque down the terminals.

[T3sl4co1l]

Ferrules (or some other means of keeping the strands bound together) are also required to meet CE requirements, if that should be an issue.

Tim

[bitbanger]

If the terminals are not exposed to harsh conditions you will be fine with bare stranded wire. However if subject to vibration or heat cycling you will be glad you used them. Ferrules are expensive in my mind so I only use when needed/required. They do offer a more professional look if the terminals are visible to the customer.

The best budget crimper (for occasional use) I've found is below. If you're talking a lot of terminals, best to invest in a ratcheting type.

http://www.greenlee.com/products/CRIMPER-TRPZD-23%2540d13.html?product_id=19110

[Paul Moir]

It's one of those things where price depends a lot on where you buy them.  For example:
http://www.automationdirect.com/adc/Shopping/Catalog/Wiring_Solutions/Wire_End_Connectors/Insulated_Ferrules/Standard_Color_Single_Wire/BM-00503
($7.50 for 500, 0.015 each) 
http://www.digikey.ca/product-detail/en/1181010/288-1015-ND/266380
($53.00 for 500, 0.105 each)

I do agree that it is expensive to build the stock of all the various sizes you end up needing, and that the world got along without them for a very long time.

[ajb]

Ferrules pay for themselves the first time you have to remove the wire and can put it back in the terminal without having to clean up the mangled stripped end first.

[TheElectricChicken]

ha! I was looking at pictures of those on a shopping site and wondering how they were used and what for. I couldn't work out how they'd work without solder or crimping. but now I guess I know, cool ! must try. I use crimp terminals for ages now and can't work out what i did before that.

[McBryce]

Ferrules need to be crimped too.

Bryce.

[TheElectricChicken]

Thanks. So I figure it'll be strip cable, thread into ferrule, crimp shiny, stick it into screw terminal and tighten.

[tautech]

Thanks. So I figure it'll be strip cable, thread into ferrule, crimp shiny, stick it into screw terminal and tighten.

Exactly.
They're called bootlace ferrules in this part of the world.

[McBryce]

Thanks. So I figure it'll be strip cable, thread into ferrule, crimp shiny, stick it into screw terminal and tighten.

Yup. Here's what the crimper looks like, the metal is pretty thin, so the tool doesn't need to be huge: http://g03.a.alicdn.com/kf/HTB1gypqIVXXXXbCXFXXq6xXFXXXi/Crimping-Pliers-for-Cable-Links-Crimping-of-Wire-End-Ferrules-Crimping-Tool-New.jpg

When they're crimped they look like this: http://www.epanorama.net/newepa/wp-content/uploads/2014/02/crimpresults.jpg

In German they're called "aderendhülsen"

McBryce.

[TheElectricChicken]

In German they're called "aderendhülsen"
McBryce.

Very cool and informative.

[pstemari]

Yes, I have good quality ratcheting crimpers (the one from Powerwerx and a Greenlee/Paladin PA8000) and an assortment of dies.

I wound up using spade lugs.  AFAICT the ferrules work best in Euro-style terminal blocks and aren't as effective with the clamp-style connections on these switches. The ferrule would be on one side or the other of the screw in the clamp.  The spade/fork goes to either side of the screw and the crimped connection with nylon insulator is much less likely to fray the strands than the edge of the clamp.

[MarkF]

I have been looking for an assortment pack to get started with and found this 800 piece AWG 22-10 Kit on Amazon.  And this IWISS Crimper Plier HSC8.