Flex ware inverter bypass slide [RE-wrenches]
boB Gudgel
boB at midnitesolar.com
Fri Nov 30 11:45:37 PST 2007
>From Robin:
Aint competition grand? Some of us handle it better than others I
guess.
I will address the issues that were brought up.
AC bypass switch: This is a transfer switch. It does not need to be made
with circuit breakers. The MidNite bypass switch operates very smoothly
indeed. This is not an easy task. The AC bypass switches I designed at
Trace engineering, OutBack and MidNite are all similar, but slightly
different. They all meet the UL requirements and they all function
properly. It becomes a personal preference, not a safety or a NEC issue.
Transfer switches are not required to turn both circuits off at the same
time. Store bought transfer switches like the Square D at Trace work
like the MidNite bypass switch.
Separate bypass switches: This style of bypass is not as convenient as
one that operates two or more inverters at the same time, but it is not
a safety issue. Fifty thousand bypass switches that work like the
MidNite bypass have been installed from Trace, Xantrex, OutBack and
Midnite over the last 13 years or so. Remember, we use breakers in
place of the switches, so in the unlikely event that something went
wrong, the breaker would trip. I am not aware of a single instance where
this style bypass switch led to a problem. In a previous post, I
mentioned an upcoming product that addresses the issue of single vs.
dual vs. quad bypass switches. What this means is that you will have
more choices available soon for larger systems. 95% of the E-Panel
installations have been single inverters. Dual E-Panel installations do
not yet have such a clear cost advantage over the competition as the
single E-Panel installs.
Another accusation about our bypass switch has to do with moving both
the inverter output and the bypass breaker together at once. This is the
way we did it for years at OutBack and how it is now done at MidNite.
The OutBack bypass switches on dual and quads were changed to the
present configuration while I was still president of OutBack. I actually
made those changes. The reason for the change had nothing to do with
safety. We just couldnt get all the tolerances down to make a smooth
operating switch, so we opened up the slots. This forces the user to
manually turn the one switch on after flipping the slider. It also
allows both breakers to be turned off. Either method is ok. NEC requires
a separate generator disconnect box if the generator is not within site
or is remote. This is more convenient and more obvious as the AC input
disconnect if done separately. My electrician installed a separate
generator input disconnect before the PS2 panel to meet code since my
generator is remotely located. The PS2 can turn off both breakers at the
same time, but my electrician did not believe this was adequate. Some
installations do not require a separate generator disconnect due to
proximity.
One more thought comes to mind to disconnect power
How about turning
the inverter off! Use the big DC breaker or the inverter on/off switch.
The output is then isolated by the contacts inside the inverter relay.
Some installers add a 50 amp output disconnect breaker inside the
E-Panel when needed. This is another way to create a clearly labeled
method to disconnect the house loads. Since the issue here is to make
sure there is no power going to the house loads it would be wise to turn
the generator off before working on the system. As discussed here, there
can be disconnects installed before or after the power source. This is
not a requirement of the E-Panel to meet code. Thousands of E-Panels
have now been installed and inspected without issues.
Door grounding: The comment about our system being unsafe due to no
ground is false. Has anyone ever heard of putting a ground wire from the
equipment ground terminal on the inverter to the ground terminal in the
breaker box? All E-Panel doors come with a wiring diagram that clearly
shows the inverter grounded. Screws and star washers ground the inverter
to the chassis when shut, but to insure grounding while the door is
open, you should install a 6awg green THHN ground wire (follow the NEC
code). Equipment grounding is always required.
Cabling: The cables that run from the battery breaker and shunt to the
inverter do not loosen up. This issue was addressed at the beginning
with ETL before I started designing the E-Panel. The statement that our
design is going to cause a fire is just not true. The E-Panel is a
different kind of breaker box. I knew people would be taking pot shots
at it, so ETL and I reviewed the cabling and wiring issues early on.
This is not something that was slipped by the ETL inspector while he
wasnt looking. I have been working with this same ETL engineer for over
a dozen years and believe me; he does not let anything through that does
not meet UL standards. Most of the Trace Engineering equipment, lots of
Xantrex, all of the OutBack, all of the Magnum, most of the PV Powered
and all of the Midnite products were evaluated by Tony Dorta of ETL.
Tony is very respected by manufacturers in the RE industry.
The MidNite E-Panel does not hold as many breakers as other boxes. That
is true. The Stretched OutBack E-Panel will accept up to 6 additional
field installed din rail mount breakers and two panel mount breakers in
addition to the AC bypass, AC input and inverter battery breaker. The
stretched OB E-Panel has mounting for up to four shunts at once.
Competition is good. False accusations are not. Per the moderators
request, this is a one time response. I consider this thread closed.
The market is pretty good at sorting out what they like.
I thank you for your support, past, present and future.
Robin Gudgel
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