Acquired this Bus- how’s the panel look?

[Nick5272]

Hey folks, we recently bought this converted bus and this is the AC panel. I’m curious what you all observe. I had not gotten to the electrical research in our original build before we acquired this bus so I’m not sure what to look for. Posted this in an electrician forum on Reddit and was told it’s a 240V panel set up for 120V and that it wasn’t good. Curious y’all’s thoughts. Thanks! https://imgur.com/a/bAcurbp

Also here’s the pic on Imgur for clarity https://imgur.com/a/bAcurbp

 

[rossvtaylor]

Hi Nick, it's common to use a split-phase (240V) panel like that. There are two bus bars, one for each line in a 240V feed, and in the case of a purely 120V system you can route your 120V single-phase feed to both bus bars...which they did at the top with that breaker and the red jumper.

From what I can see, this looks fine and actually pretty well done (with one exception). It appears that they used 12ga wire for the 20A circuits, which is proper, and the wires aren't entering the panel housing through bare holes...they used grommets. The glaring exception I see, which you should correct, is they installed the green bonding screw in the neutral bus bar...and that should be removed. That screw bonds (creates a path between) the neutral and the ground, but that bond should only happen at the source of power. If your source is an inverter, then the neutral-ground bond should happen at the inverter. If your source is shore power, then that bond should happen at the shore power source. And if your source is a generator, then that bond should happen at the generator. This panel should be set up like a sub-panel, in which case that green screw is not to be installed. Just remove it and make sure the neutral-ground bonding happens at your source, then you should be all set.

 

[DeMac]

Looks Good

To me, it's clear that the work was done completed by a residential Electrician. It's a very clean panel installation. Like Ross stated above, remove the green grounding screw, for all of the reasons already given.

I don't see a bare, solid #8 or #6. Is the panel ground, bonded to the chassis?

Based on what I see here, I'd expect the entirety of your electrical system was completed safely. You selected well.

 

[Nick5272]

Thanks for the feedback! Ross, for removing that green screw in the upper right is it as simple as shutting off the main breaker then unscrewing it or does that entire white wire need to move somewhere else? I took it to mean the green screw bonding at THAT site is the problem.

And Demac, I’m not sure currently. I’ll link some pics below of the electrical equipment. It was built by Sojourner’s Way and is pretty sweet!

 

[Nick5272]

Here’s the pics of the victron Solar and batteries
https://imgur.com/a/aDreskh
https://imgur.com/a/aDreskh

 

[Rucker]

Agreed. You should just be able to turn off power temporarily and remove that green screw.

 

[rossvtaylor]

Thanks for the feedback! Ross, for removing that green screw in the upper right is it as simple as shutting off the main breaker then unscrewing it or does that entire white wire need to move somewhere else? I took it to mean the green screw bonding at THAT site is the problem.

And Demac, I’m not sure currently. I’ll link some pics below of the electrical equipment. It was built by Sojourner’s Way and is pretty sweet!

Hi Nick,

Yes, you can remove just that green screw. There shouldn't be any power (electrical potential) at that point, so it's pretty safe to remove even with the power on. The risk is that you might touch something else with the screwdriver...or your skin...so that's the reason for shutting off the power. So, yes, for safety...shut off the power and remove that screw and you're good to go.

BTW, I know Jonathan (Sojourner's Way) and if he did the work then I would strongly presume it's done right.

 

[jonbobshinigin]

Hey! Ross pointed me here. Jonathan sour Sojourner’s Way…the panel was wired by and Electrician. Technically the red jumper bypasses one side of the breaker…but given the wire size, and the Inverter size (4000w), I cannot see how it would be a problem. I do not use residential panels and I was very clear about the neutral and ground not being bonded.

There is a 6/4 SOOW feeding this panel from Inverter and I repurposed the Red Line (you’ll see it on bottom left on Ground rail) to Ground the panel to “Chassis”, which is all done through the Lynx Bus Bar.

 

[TucsonAZ]

It does look good, the only obvious thing to point out for somebody new to electrical is that if you installed a double pull breaker designed for 240v both sides would be in phase with each other so you wouldn't be able to run something that was 240v like a dryer or welder. If you did move to two inverters that could do split phase the box would allow for that though so that's an upside of you ever dicided you needed it.

 

[rossvtaylor]

Hey! Ross pointed me here. Jonathan sour Sojourner’s Way…the panel was wired by and Electrician. Technically the red jumper bypasses one side of the breaker…but given the wire size, and the Inverter size (4000w), I cannot see how it would be a problem. I do not use residential panels and I was very clear about the neutral and ground not being bonded.

There is a 6/4 SOOW feeding this panel from Inverter and I repurposed the Red Line (you’ll see it on bottom left on Ground rail) to Ground the panel to “Chassis”, which is all done through the Lynx Bus Bar.

I have no doubt your part of this was done well, Jonathan. I'm not clear, though, on your observation about the red jumper wire. Used as a backfeed breaker, that jumper is just permitting the feed of 120VAC to each leg of the panel. The feed/line/source wire could have been split earlier and then connected to each side of that double-pole breaker, but the result is the same...120VAC is flowing through each side of the breaker and, since they're really two single-pole breakers with the handles tied, current in excess of the trip limits on either side will trip the breaker (both sides). Now, I didn't check to see if that breaker allows the connection of two wires (some do, some don't) and I didn't check to see if 60A is the right rating for that cable (seems higher than needed, at first glance). But feeding both legs like this is proper, for a 120VAC-only panel and I don't see how that configuration bypasses a breaker. I could be wrong, though, so I'm open to learning what I'm missing!

And, as my fellow Arizonan (hi Tucson) says, there's no 240V on this panel and a double-pole breaker won't yield 240V. The panel should be marked 120VAC only, to make this clear to the next owner.

Except for a few things to check/verify here, and removal of that ground screw, it looks like the electrician who did this work did a nice job of it.

 

[jonbobshinigin]

Ross:

This is the most common mistake that residential electricians make. With residential, you’re never feeding the Panel THROUGH a breaker; you're always sending power OUT of a breaker.

In this cases, you’ve got a 60a Double Breaker being fed with a 6/3 SOOW (actually 6/4 but the Red is just grounding box to chassis). The Inverter Peak is about 8000w from Batteries which is 66a at 120v; totally a non issue. With Power Assist, the Victron feature that allows Shore/Generator power to boost the total Inverter Output, this means you COULD outrun the 6/3. This is where a breaker should protect…

But, if you see the Line Feeding into the Double Breaker, it means you get 60a protection to just that side of the panel. But then you’ve got a jumper feeding the other side of panel…which could ALSO pull 60a. The Jumping of the two sides of the panels should occur on the other side of the Breaker. I’ve got a video in queue for this because I see it very frequently!

 

[rossvtaylor]

Hi Jonathan,

Funny...I was just coming back to this to add an edit to my post, regarding my use of the term backfeed breaker. I was going to add that my use, here, might have been unclear. In normal use, a backfeed breaker is one that's installed in a panel and which feeds energy into the panel (as opposed to drawing energy from the panel) as in the case with lots of grid-interactive (grid connected) inverters and devices. Per the standards, a breaker is suitable for backfeeding (also called reverse-feed) unless it's marked with specific line and load side markings, in which case it's not rated for backfeeding.

"Per UL 489 Paragraph 9.1.1.13: Circuit breakers shall be marked
“Line” and “Load” unless the construction and test results are
acceptable with the line and load connections reversed."

It's common to use such a connection in grid-tied systems. It's also covered in NEC 705.12 (which discusses this and a related 120% busbar feed limit). This panel isn't grid interactive, but I used the backfeed term to distinguish the direction of electrical flow through breaker and into the bus bars.

I do agree that this configuration has the theoretical potential to draw 120A through that source/line cable...but I'd presume the source (inverter) has a limit on the output. However, yes to be safest, that single cable should be sized to safely carry the max possible current flow...which would be limited by the source (an inverter limit or some OCPD near the inverter) OR by using a smaller breaker in the panel. And yes, as you suggest, a single breaker could be installed on the source/line cable and then the output of that breaker could be split to feed each leg of the panel...but this panel doesn't have lugs on the legs/bus bars, so they'd have to install a separate box with a breaker that would then feed into this double-pole breaker anyway (since that's how this panel is designed to be energized).

I do admit that I presumed...which isn't good...that the line to this panel is protected or limited earlier in the chain. Any OCPD in the panel, like this breaker, won't offer any protection to chafing or rodent chewing or other compromises or shorts before the panel.

Anyway...all good things to think about and the key takeaway is that all wires should be protected (as close to the source as possible) with appropriate over-current protection.

 

[rossvtaylor]

Additional post to add a note...because I was too late to edit my prior:

The short summary of this is that, yes, the wire/cable from the source (the inverter) to the panel needs some protection from overcurrent. That protection has to happen near the source, not at the panel end. The double-pole breaker in this panel is essentially just a switch, since it does nothing to protect the wire upstream (on the source side) of the panel. Jonathan and I chatted and he said this panel is a bit wasteful and more complicated (and costly) than necessary in a bus...and he's right. If I were designing a system from scratch, I'd have picked other components too. But, looking at what's here and how it's done, I think it's just fine...no need to change anything (besides that screw mentioned earlier).

The TLDR (as the hip kids say) is: overcurrent protection, whether it's a fuse or a circuit breaker or (possibly) a BMS current limiter, has to happen as close to the source of the power as possible so it can protect the wire and devices downstream of it. Any wire between the OCPD and the source is unprotected.