I have a customer that removed the ground socket (the round one) from
a pojectors cable in a fluctuation power environment.  More than 2
projectors have been destroyed from this.  But the customer does not
understand that it is the removal of the the ground socket that is
causing this.

Here's my question:  Where can I get specific resources or sites on
the web that will show it is the customers fault and not the product?

---

Request for Question Clarification by maniac-ga on 11 Oct 2005 19:08 PDT

Hello B4b42day,

Hmm. I tend to agree with the comments - the ground plug is generally
used to improve safety and is not necessary (but IS strongly
recommended) for operation. See
  http://www.peavey.com/support/technotes/safety/shockhazard.cfm
for a nice explanation of the issues involved.

It is odd to met that a customer would cut off the ground plug since a
2 prong adapter costs less than $2
  http://www.business-supply.com/office_supplies_2045002_fellowes-3-prong-adapter.html
and would avoid the "modifying equipment" issue. There are also
versions that have a ground wire or attachment like this one:
  http://www.adorama.com/ZZAC32.html
which would allow the customer to properly ground the equipment. You
may want to suggest using one regardless of other actions.

There are some more serious alternatives you could consider:

[1] Hook up a power monitor such as
  http://www.microdaq.com/aemc/power-quality/pql-100.php
Yes - its pretty expensive but it could give you the data needed on
power flucutation to analyze / determine that the equipment is
connected to bad power.

[2] Hook up an Uninterruptible Power Supply (UPS) such as
  http://www.apc.com/products/family/index.cfm?id=21
This is certainly a lot less $$ and would pretty much eliminate
fluctuating power as a cause. Note that the UPS should be plugged into
all the devices being used together (e.g., computer & projector) and
that if a phone line (modem) or wired network are used - to protect
those as well.

I am also not quite sure what you mean by "fluctuating power" and the
"projectors are destroyed". You may want to explain those terms more
fully.

I have certainly seen equipment destroyed by high voltage spikes - a
surge protector would help rule that out (or the UPS above) from the
power line. However, if the computer and projector have separate
grounds - the cable connecting the two could have enough voltage (and
current) to destroy the interface electronics on one or both sides.

  --Maniac

Can you explain why you think removing the ground plug would ruin the projector?

If the customer alters the product in any way, then all warantees are
void.  It is, by definition, the customer's fault, whether there are
technical reasons or not.

try this webpage 
http://www.allaboutcircuits.com/

The ground plug is purely for safety and has no effect on the proper
operation of an electrical appliance. It accomplishes two things.
First, it assures that the plug is inserted with the proper
orientation so that the hot wire of the socket is connected in a
predictable way to the appliance. Second, the safety ground wire is
typically used in appliances that have a conductive case and the case
is connected to the safety ground. If a short circuit were to occur
inside the appliance, any current will be passed through ground,
rather than through the body of someone who touches the conductive
case.

The appliance will work just fine if the ground plug is removed or if
the hot wire and neutral wire are reversed. Thus, I ask again, why
would you think removing the ground plug would damage the projector?

The devices work OK when we test them but after we give them to this
same customer, they send them back stating that they are damaged.  The
same thing happened when a laptop was taken to the same environment
(fluctuating electricity environment) that has only 2 plugs and no
ground.

I believe that it has something to do with the following:

1.  The fluctuating electricity
2.  The removal of the ground plug.