Subaru Outback Forums banner

a 3 prong socket mod?

6K views 40 replies 12 participants last post by  Looby 
#1 ·
i know Subaru has this as option has anyone done it them selves? i think its a 110v plug, but it looks like its only a 2 prong anyone try a adding a 3 prong and what would you plug into it? like a playstation! :D:rolleyes:
 
#2 ·

Is the "neutral" side of the 2-prong outlet bonded to chassis ground?
If so, a 3-prong mod should be simple. ...otherwise, not so much.

 
#3 ·
I am not so sure you can have 3 prong outlet because the car is on rubber tires and you would have to "ground" it... few years back there were these metal "whiskers" that would touch the sidewalk curb but that was more for looks than to serve any meaningfull purpose....
 
#5 ·
I am not so sure you can have 3 prong outlet because the car is on rubber tires and you would have to "ground" it... few years back there were these metal "whiskers" that would touch the sidewalk curb but that was more for looks than to serve any meaningfull purpose....
The whiskers do actually serve a purpose: warning the driver that they're too close to a curb when parking to avoid damage wheels/hubcaps.

But like you said, not very useful for grounding a car since they're not in contact with anything while the car is away from a curb.
 
#4 ·
I just always keep a 3 prong to 2 prong adaptor in my car so my laptop power cord (3 prong) has a place to plug into.
As stated earlier, the third prong is supposed to go to the real ground in your house or building (copper or similar metal whacked a few feet into earth) , and since this doesn't exist for the car, the best you could do would be to tie the car chassis to the third prong, which is not the same thing.
christopher
 
#17 ·
...the third prong is supposed to go to the real ground in your house
or building (copper or similar metal whacked a few feet into earth)...
Not quite. The third prong is supposed to be a duplicate "safety
path" to the power supply's "neutral" side (if one exists). A normal
(USofA, 110V) 2-prong outlet has a "hot" side and a "neutral" side.
A 3-prong outlet adds a "ground" wire -- in case the "neutral" wire
fails. The third prong is hardwired to Planet Earth, only because
the local power company also connects their 2-prong "neutral" to
Planet Earth. In normal operation, "neutral" and "ground" are at
the same potential -- 0.0 volts, relative to your vegetable garden.

It used to be the case that 2-prong 110V outlets on steel-hulled
naval ships had no "neutral" side. Instead, both sides were "hot"
with +/- 55 VAC (nominally) relative to hull-ground. I don't know
if USN 110v outlets still work that way, but I mention it because
it's possible that Soobie's 110v outlets are setup with no neutral.
If they are, adding a (working) third prong could be difficult.

...Murphy was an optimist,

Looby
 
#6 ·
They were called curb "feelers".
The rage in the late 50's. Not for grounding.
To avoid shocks, some would put a "grounding strap" on the chassis that would drag on the ground at low speeds and discharge static electricity to avoid shocks in dry weather. Tire manufacturers have now added something to the formula for rubber, so now the tires dissipate the charge somewhat to avoid shocks. Not sure what any of this has to do with your plug, but there it is.
 
#7 ·
Yes, that what is was: curb feelers... now I remember... and also that strap dragging ... that was to avoid possible hazzard when re-fueling (I thought then). They have those pump hoses grounded now - but, in the 50's, they might not have been grounded then...if I remember correctly.... getting old....
 
#8 ·
Our Ford has a 110v outlet. Its three prong but the ground is just a blank hole. Wish Subaru would have done it this way.
 
#15 ·
There is a 110V kit available from Subaru... installation is a bit complicated though... I added a cig. lighter outlet/socket there instead!
You can always buy a cig. lighter/socket converter to 110V and plug it in a cig. lighter socket....
 
#24 ·
Very cool Looby - you nailed it!!
On my 2011 outback with factory installed 110 volts, I measured +/-55 volts between each socket and the car chassis tonight using a multimeter. Of course 110 volts directly between the two sockets. Seems consistent with what you said about the Navy implementation.

That being said, would it not be advantageous to electrically connect the chassis of the plugged in device (e.g. computer, tv etc) to the car chassis, using the third prong, with the goal of eliminating shocks when touching the device chassis in the event of a short between the device chassis and the car's 55/110 volts? Basically you'd be tying the device chassis to the car chassis. Or maybe there's something I'm not getting here.

Christopher
 
#25 ·
That being said, would it not be advantageous to electrically connect the
chassis of the plugged in device (e.g. computer, tv etc) to the car chassis,
using the third prong, with the goal of eliminating shocks when touching
the device chassis in the event of a short between the device chassis and
the car's 55/110 volts? Basically you'd be tying the device chassis to the
car chassis.
You have the right idea, i.e., connecting the exposed surfaces of a 110v
appliance to the car's chassis via a third prong "ground" might possibly
reduce the risk of shocks to passengers -- but it's hard to say for sure
without knowing a whole lot more about the inverter's circuitry. If the
inverter outputs are "fully floating" with respect to the car's chassis (or
nearly so, with multi-megohms of isolation), then a third prong "ground"
would serve no useful purpose.

Before advising one way or the other, I'd want to see a schematic of the
inverter (highly unlikely that one is available) -- or at least spend some
time poking around with 110v test loads a serious quality DMM.

...if it ain't broke, I can fix that,

Looby
 
#27 ·
... that kind of volatge and Amps can never harm anybody seriously....
That's the most amazingly clueless statement I've seen on this forum.

Looby
 
#28 ·
<TABLE border=1 cellSpacing=2 cellPadding=2><TBODY><TR><TD><CENTER>Electric Current
(1 second contact)</CENTER></TD><TD><CENTER>Physiological Effect</CENTER></TD><TD colSpan=2><CENTER>Voltage required to produce the current with assumed body resistance: <TABLE><TBODY><TR><TD>100,000 ohms</TD><TD>....1,000 ohms</TD></TR></TBODY></TABLE></CENTER></TD></TR><TR><TD><CENTER>1 mA </CENTER></TD><TD><CENTER>Threshold of feeling, tingling sensation.</CENTER></TD><TD><CENTER>100 V</CENTER></TD><TD><CENTER>1 V</CENTER></TD></TR><TR><TD><CENTER>5 mA </CENTER></TD><TD><CENTER>Accepted as maximum harmless current</CENTER></TD><TD><CENTER>500 V</CENTER></TD><TD><CENTER>5 V</CENTER></TD></TR></TBODY></TABLE>
 
#30 ·
5 mA = maximum harmless current = 5.0V @ 1000 ohm body resistance
Median body resistance is about 2k to 3k ohms, low decile is half of that.

Google it!

Assume 55 VAC, either prong to car chassis. I = E/R ...plug in the numbers.

...now, which part of "5 mA" don't you understand?

Looby
 
#32 ·
Typical meaningless blizzard of irrelevant techno-babble.

...if you can't bedazzle them with brilliance, baffle them with BS!

Looby
 
#31 ·
This is info for a GFCI plug:

"The average adult heart can take no more than about 1 watt /sec of 110V@60Hz for about 0.5 seconds before stopping. That's about 10 milli amps of 110Vac. 10 milli amps is 0.010 amp. Thus, your basic home Ground Fault Interrupting (GFI) circuit breakers are set to trip at 5 milli amps or greater imbalance current between lines caused by either line leaking to ground . The GFI sensor takes 1 cycle to detect a ground fault and the breaker mechanism will break a fault in less than 1 cycle. That's 2 cycles maximum or only 0.033 secs for the GFI to open the circuit and stop the current flow. Thus, a GFI breaker can easily save a person's life if he or she is in a ground fault path."

Current across the chest is most dangerous. Moist skin can also greatly enhance conductivity. Under certain conditions a 9v battery can be fatal. 5ma can kill you.
 
#35 ·
Moist skin can also greatly enhance conductivity.
Looby's First Law:

Never touch the float-switch for the 12V bilge pump in
a sinking boat while standing knee-deep in sea water.

...don't ask,

Looby
 
#41 ·
True 'dat, my original crapola dime-store invertor plugged
into the cigarette lighter and provided a 3 prong outlet.
The third prong on your dime-store wonder is either connected
directly to the "cigarette lighter ground," or to nothing at all. A
continuity tester (battery & bulb) will unambiguously tell which.

The other two prongs are either both "hot" at +/- 55 VAC (more
or less) or one is 120 VAC (relative to chassis) and the other is
"neutral" -- another job for the continuity tester.

"It's much easier to 'reverse engineer' a third prong that exists
than one that doesn't."
-- Looby's Second Law

...either way, it might be GFCI-protected ...or not,

Looby
.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top