Terminals in wireway


Thread Starter

Stephen Wright

Recently a machine control schematic was sent to me for approval. The
engineer had specified insulation displacement terminals, but he had
specified unmounted splice type joints for the control wiring distribution.
I rejected these terminals and told him he needed to mount traditional
terminal blocks. I did not find any specification that specifically
rejected the use of the "loose" joints, however and was ultimately overruled
by the cost saving argument. Since I would like to quote chapter and verse
to support myself, has anyone any reference or experience with this question
to offer?

Jeffrey Eggenberger

The only think I could think would knock this down would be National
Electric Code 110-12.
Electric equipment shall be installed in a neat and workmanlike manner.


Kevin Hammond


Stand your ground!! I have tried to troubleshoot such systems - not pretty. I think this should cover you:
NFPA 79 - 16.1.4
Conductors and cables shall be run without splices from terminal to terminal.

Kevin Hammond
Electronics Engineer
Norfolk Southern Corp.
These style blocks are becoming more and more poular due to cost savings and fast connection times. Panel shops love them, field personnel like the quick easy connections too. However, it's hard to believe that these connections can hold up to industrial environments and still remain tight and maintain a "gas tight" connection. The truth is, they do. I would have no problem specifying them.

Ralphsnyder, Grayg

IDTs (Insulation Displacement Terminals) are going to be seen more and more.
People like Allen-Bradley are using them with their distributed I/O products. I have difficulty in becoming comfortable with this - integrity of the connection - somehow feel that a terminal with a screw is more secure. It would probably be a good thing if NEC or UL (etc.) would generate a standard relating to IDT connections.

James Bouchard

If you are requiring that the panel or equipment be approved by an agency
line UL or CSA then the components have to also be approved by that agency
or they are subject to special investigation. So check what was requested
for approvals and then check with the approving body about the connectors.

James Bouchard
A bad practice!

You might try:

NFPA 79-1997 "Electrical Standard for Industrial Machinery," Sections 16.1.4
& 16.1.8.

While I don't have a copy to say one way or the other, you might look at the
UL 508 "Industrial Control Equipment" standards.

Bill Mostia
William(Bill) L. Mostia, Jr. PE
Independent I &E Consultant
WLM Engineering Co.
P.O. Box 1129
Kemah, TX 77565
[email protected]
These opinions are my own and are offered on the basis of Caveat Emptor.

Ramer-1, Carl

Piggybacking on Bill Mostia's post, NFPA 79 says:

Conductors and cables shall be run without splices from terminal to
terminal. Exception: Splices shall be permitted to leads attached to electrical
equipment, such as motors and solenoids; such splices shall be insulated
with oil-resistant electrical tape or insulation equivalent to that of the
conductors. "

Carl Ramer, Engineer
Controls & Protective Systems Design
Space Gateway Support, Inc.
Kennedy Space Center, Florida
(V) 321-867-1812
(F) 321-867-1495