Flex ware inverter bypass slide [RE-wrenches]

[Mark Frye]

The issue of the door grounding is interesting and the devil is in the 
details.

Yes,a ground wire from the inverter to ground buss will ground the 
inverter, but what about the sheet metal of the door itself.  This a 
piece of conductive material that could become energized, and must be 
properly ground at all times, door open or door closed.

A standard method is to install a stud into both the door and the box 
and use a braided ground strap to bond the door (see most Hoffman 
enclosure with hinged doors).

Unless the door is properly bonded to the inverter chassis by some 
specific method, it sounds like the MidNite falls short in meeting this 
requirement.

boB Gudgel wrote:
> 
> 
> From Robin:
> 
> Ain’t 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 couldn’t 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 
> wasn’t 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 moderator’s 
> 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
>  



Berkeley Solar Electric Systems


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