DIYbanter - View Single Post - 2-prong outlet, 3-prong power strip

bud--

On 2/11/2021 11:10 PM, wrote:
On Thu, 11 Feb 2021 16:58:22 -0600, bud-- wrote:

On 2/10/2021 2:53 PM, wrote:
On Wed, 10 Feb 2021 05:09:35 -0800 (PST), trader_4
wrote:

On Wednesday, February 10, 2021 at 1:58:09 AM UTC-5, Jim Joyce wrote:

Since someone started this thread up again, might as well point out
that if you were to plug a 3 prong surge protector into a two prong ungrounded
receptacle using an adapter, there are a few issues.

First, it's an old system and it's unlikely that a ground is present at the
receptacle box. An adapter is really supposed to be used by using the
wire to ground to the box via the cover screw. But very few are used
that way and even then unless the box is grounded, which is unlikely,
it's useless. So if you did that, the computer and anything else plugged
into the strip would not be grounded.

Next is the issue of what happens to the surge protection. Without
a ground, that path for the surge to dissipate is gone. You would
still have clamping though that would limit the voltages between
the conductors and between the conductors and the strip and
PC ground. So you'd have some protection, but not the best.
A GFCI would provide safety protection from faults that could
be dangerous without a ground, but it won't change the surge protection
issue as there still is no ground.

The only way to be sure about the ground is by using a bug eye tester

Those tester will probably show if the ground is good. But the tester
uses a very small current for the test, and will indicate good if there
is a high resistance in the ground path, like 100 ohms. A ground path
with 100 ohms resistance is useless. A more reliable test would be
connecting a 200W light bulb from hot to ground. I have a tester that
tests with a relatively high current pulses. I think from a previous
thread you have a similar tester.
They do make better testers that will look for a resistance between 1
ohm and some smaller amount.
They verify a reasonable grounding impedance and will also detect a
neutral connected to the ground by the fact that the resistance is
virtually zero.
Ecos makes the one I have.

The one I have is also an old Ecos. I haven't had it out in years.

A GFCI will trip on a N-G short downstream. It is a feature that was
added many years ago. There is a second current transformer that tries
to inject a small current on the H and N. It is only possible if there
is a N-G short (or reverse wired H-N and a H (which is now N)-G short.