1
1: The 3M Scotchlok 905 connector is sized for 18-14
AWG solid or stranded wire in the through “run” fitting and
22-18 AWG solid or stranded wire in the “tap” position.
No insulation stripping is necessary.
QUESTIONS AND ANSWERS
Suitcase connectors
Q.
I went to the local electrical supply store to get some 3M
suitcase connectors, mentioned in an article, to wire up the
DCC bus and feeders for my model railroad. The counter guy
didn't know what I was talking about, and I didn't have a
sample to show him. We eventually found the right thing, but
what's up?
A.
To the counter guy, that's an insulation displacement connec-
tor, or IDC. “Suitcase connector” was the coining of some model
railroad writer many, many years ago, and you won't find the term
used outside of model railroading. Yes, they do kind of look like
tiny suitcases (1). For phone lines, flat cables, and other special-
ized uses there are other IDCs that don't look like suitcases at all.
IDCs, when handled correctly, can save some upside-down sol-
dering under the layout. They provide a long-lasting connection
when used with correctly sized wire. The connectors come in a
couple of sizes and are color-coded. Knock-off copies of the 3M
product are also sold, but reports vary as to their reliability.
The “run and tap” connectors commonly used for model rail-
road power supply wiring have a channel for each size of wire.
You don't need to strip away the insulation. The connector wraps
around the larger wire (“run”). The smaller gauge pushes into
a stub connector at the top (“tap”). The connection is made by
folding over the connector lid and clamping it with special pli-
ers, or with lineman's or slip-joint pliers (2). The special tool and
connectors are available fromMicro-Mark, from electrical supply
houses, and from some big box home improvement stores.
Here's the 3M product page:
Questions, Answers & Tips - 1
MRH-Dec 2013
