I just had an upgrade for my electric service to a 200 Amp panel as
part of an HVAC upgrade. At the same time, I had the electrician put
in 2 220 circuits and 2 120 circuits for my shop (lights were already
separate). Last night I switched over my table saw to 220. Wow,
start up is almost instant.
The question: I plan to switch over my bandsaw to 220 as well. What
happens to the gooseneck lamp? The switch over instructions don't
mention it. Rewiring for the motor is pretty straightfoward. Am I
Well, split-voltage appliances (ranges, dryers, ...) have run that way
for approaching 100 years w/o any significant issues.
Only w/ a relatively late NEC revision did the requirement for 4-wire
service come into play.
While it strictly speaking, isn't up to current Code, for a load no
larger than the work lamp there's no issue imo.
This came up not too long ago and someone noted that between an early
manual and later the particular manufacturer of his dp had dropped the
illustration/wiring diagram for the split voltage, undoubtedly to
maintain strict Code compliance from a liability standpoint. However,
they hadn't changed the wiring iiuc... :)
Yes, that reason is Code. Having worked on various Standards groups
over the years, there's a definite tendency to continue to make
modifications simply for the purpose of appearing to continue to do
something and thereby justify the existence of the body.
In the 100 years before, where's the overwhelming evidence it was ever a
As I said, one can choose but it's certainly not a major actual problem
or there wouldn't have been the history of successful applications (and
lord knows how many still existing appliances????) w/o any issues.
When's the last time you _EVER_ heard of it being the cause of anything?
The NFPA is known to write the "code in blood". Someone was injured
or killed before the code was modified. Sure, you'll likely get away
with it but it is *NOT* smart to knowingly flaunt the electrical
code. Lawyers love it, even if you don't kill anyone.
Depends on your definition of "overwhelming". It was never a good
idea to tie a current carrying conductor to the case of a device.
That's essentially what you're advocating.
Absolute nonsense! There are many dangerous practices that are no
longer acceptable. This is one.
When I was *nailed* off my MIL's dryer (after she'd been complaining
for months I took a look at it). Had it a safety ground it would
never have shocked anyone. The code wasn't changed for this one
instance (that they never knew about).
Just don't do it, and stop telling others to violate safety codes!
You're being irresponsible!
I'm not "telling" anybody to do anything--I'm simply pointing out it's
been common practice until quite recently.
As for your experience, there has always been an external safety ground
supplied on driers; whether one bothered to hook them up is another matter.
I stand by my contention the 3-wire split circuit existed in such
numbers for so long that if it were truly a dangerous practice it would
have taken far less time than it did for it to finally percolate its way
to the radar screen.
I'll also reassert given my experience on Standards committees there is
that aforementioned need to find _something_ to modify...they finally
got to the bottom of the barrel where this became one thing they could
find to change.
again, imo, ymmv, etc., etc., etc., ...
And, yes, Code now mandates 4-wire connections; others make your own
determination, I'm not advocating you violate Code willy-nilly but the
subject of a work light on a drill press...
There has not always been a grounded conductor on driers, only a grounding
conductor. Unfortunately, in the olden days, the grounding conductor has
been used as a grounded conductor as well for 120 volt loads, which can
cause the frame (which is attached to the grounding conductor) to have a
potential difference relative to earth. (if they didn't bother to hook up
the "external safety ground" as you call it (NEC calls it the grounding
conductor), the light in the dryer wouldn't work at all, so it's quite
likely that they _did_ bother to hook them up in almost all cases).
Modern NEC requires both a grounding and a grounded conductor on 240v/120v
Read what I wrote instead of looking for an axe to grind and to try to
show how shumart thou art... :(
I didn't write "grounded conductor" I wrote "external safety
ground"--two different things but the latter solves a large portion of
the problems (but they were often never connected or to an adequate
ground in practice)...
On Tue, 1 Sep 2009 10:58:01 -0700 (PDT), " email@example.com"
I'm not sure if "dpb" was referring to me, or not, but I found that
with my DP. Motor can be rewired for 240, but the wiring harness has
no provisions for a neutral feed. The "stock" harness connects the
work lamp across the two non-ground leads so that if the DP is plugged
into a 120v circuit, the lamp socket sees 120. And if plugged into a
240v circuit, the socket sees 240v. I'd strongly suspect the OP's band
saw is similar. He'll certainly find out if he rewires the motor for
240 and his work light (with a 120v bulb) burns very brightly for a
very short time.
Several years ago, on the manufacturer's web site, the PDF manual for
the DP, as a part of the diagram for rewiring the tool for 240, showed
the work light socket being changed to connect across one hot lead and
the EGC to provide 120 to the lamp. I went back to the site at a later
date, and that part of the diagram was no longer there. It now shows
only a configuration that connects the lamp socket across the
non-ground leads with no direct connection to the EGC. I suspect the
diagram was deleted as a result of UL requirements.
Using the EGC for an operational conductor does violate the current
NEC. But, the NEC doesn't cover anything beyond the wall plug. It's
only applicable to permanent wiring, so rewiring the DP (or band saw)
to supply 120v from a 2+G 240 circuit doesn't technically violate the
NEC unless the device is hardwired into the facility wiring. That
doesn't mean it's any more or less safe, just that it's not covered by
the NEC. That's according to my understanding of the scope of the NEC.
Even if "plug in" loads was covered by the NEC, compliance would be
impossible to enforce unless you had to pull a permit and get an
inspector out every time you plugged the vacuum cleaner into the
living room wall socket.
Using the tool's EGC for a neutral return will, as stated, energize
the grounded portions of everything connected to that circuit, as well
as everything on every circuit which has an EGC connected to the
ground bus in the panel that houses that circuit. The voltage on those
energized grounds will be the product of the resistance to ground of
the panel's ground bus times the current flowing from the ground bus
to ground. May or may not be dangerous depending on the amperage and
the resistance to ground.
Incidentally that is the same condition that exists if any device
drawing current through that panel develops a short to ground. Until
the breaker trips (assuming the leakage to ground is enough to trip
the breaker) every grounded item in, or connected to, that panel will
be energized with that amps x resistance voltage.
The use of GFI breakers addresses that condition by tripping anytime
there is a very small difference in the amperage in the two non-EGC
conductors. Otherwise the fault current would have to be on the order
of the breaker rating. A DP or BS rewired to use the EGC as neutral on
a 240v circuit would certainly trip any 240v GFI breaker that
monitored the current in the two hot wires the way a 120v GFI breaker
monitors the current in the hot and neutral wires.
Yes, it was you, Tom; that's the description I recalled, just couldn't
I'm willing to bet that's the same scenario OP has--a machine built
before the change and documentation of same removed to avoid the issue
from their end.
Heh heh, I had that kind of experience when I converted my arc welder
from 230V to 400. No more sticky electrodes! (NB: I'm not in the US,
230V is our 'normal' voltage).
I believe 400V on a thicknesser is a nice thing to have, too. My fairly
light German over and under planer/thicknesser has just about done its
dash; and it doesn't owe me much either after 26 years. I might give
that a second thought.
I am no electrical expert but iIwould guess it will work OK. If you have
normal residental home wiring you will actually have 2- 110 volt lines going
to your BS. Add them up and you get 220 volts. The lamp will probably
continue to have 1 single 110 volt line going to it.
Electric ovens and ranges have the same set up.
Good point Leon. I know in a 4 wire 220 supply you can have two hots,
a neutral and a ground. The outlet and plug will only have a 3 wires
(2 hots and ground). I haven't pulled the plate off of the motor yet,
maybe there is more info there. I am a bit shocked (no pun) that
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