<s>
A	O
banana	B-Protocol
connector	I-Protocol
(	O
commonly	O
banana	B-Protocol
plug	I-Protocol
for	O
the	O
male	O
,	O
banana	B-Operating_System
socket	O
or	O
banana	B-Protocol
jack	I-Protocol
for	O
the	O
female	O
)	O
is	O
a	O
single-wire	O
(	O
one	O
conductor	O
)	O
electrical	B-Protocol
connector	I-Protocol
used	O
for	O
joining	O
wires	O
to	O
equipment	O
.	O
</s>
<s>
The	O
term	O
4	O
mm	O
connector	O
is	O
also	O
used	O
,	O
especially	O
in	O
Europe	O
,	O
although	O
not	O
all	O
banana	B-Protocol
connectors	I-Protocol
will	O
mate	O
with	O
4mm	O
parts	O
,	O
and	O
2mm	O
banana	B-Protocol
connectors	I-Protocol
exist	O
.	O
</s>
<s>
Various	O
styles	O
of	O
banana	B-Protocol
plug	I-Protocol
contacts	O
exist	O
,	O
all	O
based	O
on	O
the	O
concept	O
of	O
spring	O
metal	O
applying	O
outward	O
force	O
into	O
the	O
unsprung	O
cylindrical	O
jack	O
to	O
produce	O
a	O
snug	O
fit	O
with	O
good	O
electrical	O
conductivity	O
.	O
</s>
<s>
The	O
plugs	B-Protocol
are	O
frequently	O
used	O
to	O
terminate	O
patch	B-Device
cords	I-Device
for	O
electronic	O
test	O
equipment	O
such	O
as	O
laboratory	O
power	O
supply	O
units	O
,	O
while	O
sheathed	O
banana	B-Protocol
plugs	I-Protocol
are	O
common	O
on	O
multimeter	O
probe	O
leads	O
.	O
</s>
<s>
A	O
competing	O
claim	O
is	O
made	O
for	O
the	O
General	O
Radio	O
Company	O
,	O
which	O
stated	O
"	O
1924	O
:	O
GenRad	O
developed	O
banana	B-Protocol
plug	I-Protocol
-	O
replaces	O
pin	O
plugs	B-Protocol
,	O
this	O
spring-loaded	O
connector	O
technology	O
...	O
"	O
and	O
that	O
it	O
was	O
"	O
introduced	O
in	O
this	O
country	O
[	O
the	O
US ]	O
by	O
GR	O
in	O
1924	O
"	O
.	O
</s>
<s>
In	O
1929	O
Richard	O
Hirschmann	O
was	O
granted	O
a	O
patent	O
for	O
an	O
improved	O
banana	B-Protocol
plug	I-Protocol
.	O
</s>
<s>
The	O
patent	O
describes	O
a	O
banana	B-Protocol
plug	I-Protocol
that	O
consists	O
of	O
two	O
parts	O
only	O
.	O
</s>
<s>
Not	O
needing	O
a	O
small	O
screw	O
to	O
hold	O
the	O
wire	O
in	O
place	O
,	O
like	O
in	O
conventional	O
Bananensteckern	O
(	O
banana	B-Protocol
plugs	I-Protocol
)	O
,	O
is	O
presented	O
as	O
an	O
advantage	O
of	O
the	O
invention	O
.	O
</s>
<s>
The	O
pin	O
has	O
one	O
or	O
more	O
lengthwise	O
springs	O
that	O
bulge	O
outwards	O
slightly	O
,	O
giving	O
the	O
appearance	O
of	O
a	O
banana	B-Operating_System
.	O
</s>
<s>
Taking	O
the	O
springs	O
into	O
account	O
,	O
the	O
actual	O
diameter	O
of	O
a	O
banana	B-Protocol
plug	I-Protocol
is	O
typically	O
a	O
bit	O
larger	O
than	O
4mm	O
when	O
not	O
plugged	O
in	O
.	O
</s>
<s>
On	O
banana	B-Protocol
plugs	I-Protocol
for	O
laboratory	O
use	O
,	O
an	O
insulating	O
plastic	O
cover	O
is	O
usually	O
fitted	O
over	O
this	O
rear	O
end	O
of	O
the	O
connector	O
,	O
while	O
banana	B-Protocol
plugs	I-Protocol
for	O
speaker	O
connections	O
often	O
use	O
uninsulated	O
metal	O
bodies	O
.	O
</s>
<s>
The	O
rear	O
end	O
of	O
a	O
4mm	B-Protocol
plug	I-Protocol
often	O
has	O
a	O
4mm	O
hole	O
drilled	O
in	O
it	O
,	O
either	O
transversely	O
or	O
axially	O
,	O
or	O
both	O
,	O
to	O
accept	O
the	O
pin	O
of	O
another	O
4mm	B-Protocol
plug	I-Protocol
.	O
</s>
<s>
For	O
high	O
voltage	O
use	O
,	O
sheathed	O
versions	O
of	O
the	O
banana	B-Protocol
plug	I-Protocol
and	O
socket	O
are	O
used	O
.	O
</s>
<s>
Individual	O
banana	B-Protocol
plugs	I-Protocol
and	O
jacks	O
are	O
commonly	O
color-coded	O
red	O
and	O
black	O
,	O
but	O
are	O
available	O
in	O
a	O
wide	O
variety	O
of	O
colors	O
.	O
</s>
<s>
Dual	O
banana	B-Protocol
plugs	I-Protocol
are	O
often	O
black	O
with	O
some	O
physical	O
feature	O
such	O
as	O
a	O
molded	O
ridge	O
or	O
thick	O
tab	O
,	O
marked	O
"	O
Gnd	O
"	O
indicating	O
the	O
relative	O
polarity	O
of	O
the	O
two	O
plugs	B-Protocol
.	O
</s>
<s>
Besides	O
plugging	O
into	O
specific	O
banana	B-Protocol
jacks	I-Protocol
,	O
banana	B-Protocol
plugs	I-Protocol
may	O
plug	O
into	O
"	O
five-way	O
"	O
or	O
"	O
universal	O
"	O
binding	O
posts	O
.	O
</s>
<s>
The	O
PL-259	O
plug	O
is	O
widely	O
used	O
as	O
an	O
HF	B-Algorithm
cable	O
connector	O
;	O
it	O
is	O
a	O
shielded	O
form	O
of	O
a	O
4mm	O
banana	B-Protocol
plug	I-Protocol
.	O
</s>
<s>
A	O
number	O
of	O
widely	O
used	O
plugs	B-Protocol
are	O
based	O
on	O
combining	O
two	O
or	O
more	O
banana	B-Protocol
plugs	I-Protocol
in	O
a	O
common	O
plastic	O
housing	O
and	O
other	O
features	O
for	O
ease	O
of	O
use	O
and	O
to	O
prevent	O
accidental	O
insertion	O
in	O
other	O
such	O
plugs	B-Protocol
.	O
</s>
<s>
Many	O
of	O
these	O
plugs	B-Protocol
are	O
derived	O
from	O
the	O
"	O
double	O
banana	B-Operating_System
"	O
plug	O
consisting	O
simply	O
of	O
two	O
banana	B-Protocol
plugs	I-Protocol
spaced	O
apart	O
(	O
measured	O
from	O
center	O
to	O
center	O
of	O
each	O
individual	O
plug	O
)	O
.	O
</s>
<s>
The	O
housing	O
may	O
allow	O
the	O
connection	O
of	O
individual	O
wires	O
,	O
a	O
permanently	O
attached	O
coaxial	O
cable	O
providing	O
both	O
signal	O
and	O
ground	O
,	O
or	O
a	O
coaxial	O
connector	O
such	O
as	O
the	O
BNC	B-Protocol
connector	I-Protocol
shown	O
in	O
the	O
photo	O
.	O
</s>
<s>
Conventionally	O
the	O
tab	O
located	O
on	O
one	O
side	O
of	O
the	O
dual	O
banana	B-Protocol
plug	I-Protocol
denotes	O
the	O
ground	O
,	O
shell	O
,	O
or	O
negative	O
(	O
reference	O
)	O
side	O
of	O
the	O
connector	O
.	O
</s>
<s>
Various	O
miniature	O
versions	O
of	O
the	O
banana	B-Protocol
connector	I-Protocol
have	O
been	O
introduced	O
.	O
</s>
<s>
Multiple	O
miniature	O
banana	B-Protocol
connectors	I-Protocol
are	O
usually	O
spaced	O
on	O
inch	O
centers	O
.	O
</s>
<s>
Another	O
miniature	O
type	O
is	O
the	O
2mm	O
banana	B-Protocol
connector	I-Protocol
,	O
which	O
is	O
otherwise	O
identical	O
to	O
the	O
4mm	O
version	O
,	O
including	O
the	O
various	O
plug	O
contact	O
styles	O
and	O
availability	O
of	O
encased	O
versions	O
for	O
high	O
voltage	O
applications	O
.	O
</s>
<s>
The	O
pin	O
tip	O
plug	O
designs	O
resemble	O
banana	B-Protocol
plugs	I-Protocol
,	O
but	O
without	O
the	O
spring	O
on	O
the	O
male	O
pin	O
.	O
</s>
<s>
These	O
superficially	O
similar	O
plugs	B-Protocol
were	O
widely	O
used	O
in	O
the	O
UK	O
and	O
elsewhere	O
until	O
the	O
1960s	O
.	O
</s>
<s>
The	O
wander	O
plug	O
may	O
have	O
pre-dated	O
the	O
banana	B-Protocol
plug	I-Protocol
,	O
but	O
was	O
virtually	O
obsolete	O
by	O
the	O
1970s	O
,	O
by	O
which	O
time	O
most	O
of	O
the	O
equipment	O
requiring	O
them	O
was	O
long	O
obsolete	O
.	O
</s>
<s>
Wander	O
plugs	B-Protocol
generally	O
would	O
not	O
inter-mate	O
successfully	O
with	O
banana	B-Operating_System
sockets	O
and	O
attempts	O
to	O
do	O
so	O
by	O
spreading	O
the	O
brass	O
tip	O
often	O
ended	O
with	O
its	O
fracture	O
.	O
</s>
<s>
The	O
tip	O
of	O
some	O
banana	B-Protocol
plugs	I-Protocol
could	O
be	O
forced	O
into	O
some	O
sockets	O
intended	O
for	O
wander	O
plugs	B-Protocol
,	O
but	O
would	O
invariably	O
be	O
insecure	O
.	O
</s>
<s>
Quality	O
banana	B-Protocol
plugs	I-Protocol
and	O
cables	O
are	O
typically	O
rated	O
for	O
30V	O
at	O
15A	O
.	O
</s>
<s>
Cheaper	O
cables	O
may	O
have	O
one	O
or	O
more	O
downsides	O
:	O
lower	O
quality	O
plugs	B-Protocol
,	O
smaller	O
diameter	O
wire	O
,	O
lower	O
strand	O
count	O
wire	O
,	O
thinner	O
insulation	O
,	O
lower	O
quality	O
insulation	O
.	O
</s>
<s>
Unsheathed	O
banana	B-Protocol
connectors	I-Protocol
are	O
not	O
usually	O
rated	O
for	O
mains	O
voltage	O
.	O
</s>
<s>
One	O
reason	O
why	O
banana	B-Protocol
connectors	I-Protocol
are	O
not	O
rated	O
for	O
mains	O
usage	O
is	O
that	O
an	O
exposed	O
banana	B-Protocol
plug	I-Protocol
or	O
socket	O
can	O
present	O
a	O
shock	O
hazard	O
if	O
connected	O
to	O
an	O
energized	O
source	O
.	O
</s>
<s>
This	O
can	O
especially	O
happen	O
if	O
a	O
20mm	O
long	O
plug	O
is	O
inserted	O
into	O
a	O
socket	O
that	O
is	O
only	O
intended	O
for	O
15mm	O
long	O
plugs	B-Protocol
.	O
</s>
<s>
Some	O
banana	B-Protocol
plugs	I-Protocol
have	O
exposed	O
set	O
screws	O
that	O
are	O
electrically	O
connected	O
to	O
the	O
wire	O
.	O
</s>
<s>
When	O
stacking	O
plugs	B-Protocol
using	O
transverse	O
holes	O
in	O
a	O
plug	O
,	O
large	O
parts	O
of	O
the	O
pin	O
of	O
the	O
second	O
plug	O
are	O
exposed	O
.	O
</s>
<s>
Another	O
reason	O
why	O
banana	B-Protocol
connectors	I-Protocol
are	O
not	O
rated	O
for	O
mains	O
usage	O
is	O
the	O
lack	O
of	O
double	O
insulation	O
of	O
wires	O
and	O
connectors	O
.	O
</s>
<s>
The	O
hazards	O
include	O
electric	O
shock	O
,	O
electrocution	O
,	O
burns	O
from	O
accidental	O
short	B-Application
circuits	I-Application
,	O
and	O
damage	O
to	O
the	O
attached	O
equipment	O
.	O
</s>
<s>
Where	O
electrical	O
safety	O
is	O
an	O
issue	O
,	O
sheathed	O
plugs	B-Protocol
and	O
sockets	O
are	O
used	O
.	O
</s>
<s>
These	O
plugs	B-Protocol
have	O
fixed	O
or	O
sliding	O
sheaths	O
or	O
other	O
devices	O
to	O
protect	O
the	O
user	O
from	O
accidental	O
contact	O
with	O
live	O
conductors	O
,	O
but	O
are	O
still	O
largely	O
compatible	O
with	O
the	O
original	O
design	O
.	O
</s>
<s>
In	O
this	O
design	O
,	O
the	O
metal	O
banana	B-Protocol
plug	I-Protocol
is	O
entirely	O
sheathed	O
in	O
a	O
plastic	O
tube	O
and	O
inserts	O
into	O
a	O
deeply	O
recessed	O
jack	O
in	O
the	O
multimeter	O
.	O
</s>
<s>
Alternatively	O
,	O
the	O
equipment	O
may	O
use	O
a	O
deeply	O
recessed	O
male	O
banana	B-Protocol
plug	I-Protocol
,	O
while	O
the	O
test	O
lead	O
uses	O
a	O
sheathed	O
banana	B-Protocol
jack	I-Protocol
.	O
</s>
<s>
In	O
most	O
European	O
countries	O
,	O
the	O
standard	O
mains	O
power	O
receptacle	O
will	O
physically	O
accept	O
banana	B-Operating_System
and	O
even	O
US-style	O
"	O
double	O
banana	B-Operating_System
"	O
plugs	B-Protocol
(	O
the	O
standard	O
US	O
pin	O
spacing	O
of	O
is	O
close	O
enough	O
to	O
the	O
mains	O
plug	O
spacing	O
of	O
about	O
19mm	O
,	O
and	O
the	O
pin	O
diameter	O
is	O
also	O
compatible	O
)	O
,	O
leading	O
to	O
a	O
risk	O
of	O
electrical	O
shock	O
.	O
</s>
<s>
For	O
this	O
reason	O
,	O
throughout	O
the	O
European	O
Union	O
,	O
audio	O
amplifiers	O
and	O
loudspeakers	O
that	O
accept	O
banana	B-Protocol
plugs	I-Protocol
must	O
have	O
plastic	O
plugs	B-Protocol
in	O
their	O
sockets	O
which	O
can	O
be	O
manually	O
removed	O
by	O
the	O
user	O
.	O
</s>
