Battery Boxes...What One Company Designed

Depends on which circuit *after* the UL-listed class 2 supply you ask about.

As needed and appropriate, and depending on overcurrent devices and intervening converters, the subsequent wiring complies with:

Article 411 lighting (isolated;

Cheers? Now you've got me fretting/thinking again ;-) .

Years ago I built a mobile environmental research lab that carried a couple hundred cubic feet of H2. The lab was quite air tight and I'd work and sleep in it during Minnesota winters. The H2 was being continually used for scientific instrumentation to create a flame so it wasn't immediately discernable whether some was escaping into the lab atmosphere. The lower explosive limit of H2 is only about 4% ...

If someone has authoritative information on current best management practices for hydrogen from small battery banks such as we are discussing, I'd appreciate knowing. Also reasonable priced H2 sensors. A quick f/google showed me that they are still an obstacle to progress.

TIA ... Marc Marc_F_Hult

| >[big snip] | >| Together they provide nominal 60 amps at 28vdc and 20 amps 14vdc =~2000 | >|watts. | >| | >| A Baldor natural gas 28vdc genset has been purchased (not yet installed) to | >| kick in during power outages that has additional capacity for additional | >|28vdc | >| and 120VAC UPS needs. Controller is a Bouchette A120 | >| | >|

| >What NEC circuit class does your 28V wiring fall under? | | Depends on which circuit *after* the UL-listed class 2 supply you ask about.

What serves as the class 2 supply?

Dan Lanciani ddl@danlan.*com

In message , Too_Many_Tools writes

How much hydrogen do you think will be evolved ?

Cheers, J/.

Inteli-Power PD9180 and PD9160 (now Progressive Dynamics) as I wrote in my previous post. See

Marc_F_Hult

| >| >[big snip] | >| >| Together they provide nominal 60 amps at 28vdc and 20 amps 14vdc =~2000 | >| >|watts. | >| >| | >| >| A Baldor natural gas 28vdc genset has been purchased (not yet installed) | to | >| >| kick in during power outages that has additional capacity for additional | >| >|28vdc | >| >| and 120VAC UPS needs. Controller is a Bouchette A120 | >| >| | >| >|

| >| >What NEC circuit class does your 28V wiring fall under? | >| | >| Depends on which circuit *after* the UL-listed class 2 supply you ask about. | >

| >What serves as the class 2 supply? | >

| > Dan Lanciani | > ddl@danlan.*com | | | Inteli-Power PD9180 and PD9160 (now Progressive Dynamics) as I wrote in my | previous post. See | |

Dan Lanciani ddl@danlan.*com

They have gotten very much cheaper, smaller, cooler, more robust, more powerful

-- and Ul. and ULc. What is not quite what I'd like is efficiency for this particular family of devices. They are rated at ">80%" at unspecified load. In real world, this might mean 60% under low load. Course they may just be rating conservatively.

The RV market is big enough to the create volume needed to avoid niche-market pricing. This particular design (sold under at least three names) has been around long enough for the engineering to tested and solid. I imagine RV owners as a group are not the most gentle on equipment.

IMO, Key here is UL and internal transformer isolation. But I haven't probed to see whether it is specifically UL for Class 2. I am satisfied that it means engineering needs.

The other important part of a distributed DC system is use of isolating DC-DC converters. There are plenty of NOS devices to be had in a variety of Vin and Vout, nominal telco 48vdc being especially prevalent on the resale market.

I generally assume that all equipment that came with a wall wart and is located more than ~10m from the primary battery bank should be isolated (again) unless known otherwise. DC-DC converters also provide the current limiting to 'convert' the battery into Class 1. The NEC specifically states that a plain old zinc dry cell is Class 2 (not 1) because the potentially high current capabilities. I wonder how many door bells of yesteryear, connected with 20AWG bell wire, were in violation ? ;-)

Marc Marc_F_Hult

| >Interesting. I had no idea that you could get class 2 supplies with such | >high power output. Maybe I'll have to reconsider my low-voltage distribution | >analysis... | >

| [...] | IMO, Key here is UL and internal transformer isolation. But I haven't probed to | see whether it is specifically UL for Class 2. I am satisfied that it means | engineering needs.

Hmm. But if it isn't UL listed as a class 2 supply then it can't supply class

Another issue is that even if the supplies are listed as class 2 you can't interconnect them unless they are also listed for _that_. (721-45(b) in the 1999 NEC)

| The other important part of a distributed DC system is use of isolating DC-DC | converters. There are plenty of NOS devices to be had in a variety of Vin and | Vout, nominal telco 48vdc being especially prevalent on the resale market. | | I generally assume that all equipment that came with a wall wart and is located | more than ~10m from the primary battery bank should be isolated (again) unless | known otherwise.

I assume that anything that came with a wall wart needs to be isolated regardless of location unless it has no other external connections. Sometimes the negative power input is not common with the "common" of any other connection. Very annoying...

| DC-DC converters also provide the current limiting to 'convert' | the battery into Class 1.

You probably want to "convert" to class 2, but I don't know if DC-DC converters are generally listed for that. (If you convert to class 1 then you are stuck with class 1 wiring materials and methods on the load side, making the whole thing more trouble than running high voltage to a wall wart. :()

|The NEC specifically states that a plain old zinc dry | cell is Class 2 (not 1) because the potentially high current capabilities.

It's sort of the other way around. A dry cell (provided it is < 30V and has

Oh yes...that answers why no active venting...the batteries were indeed sealed.

Thanks for answering that little mystery.

TMT

A question for the group...

This battery box I have has its batteries arranged in two groups of four with one group mounted above the other group.

How have you organized your battery box?

Are they all laid out horizontally, stacked on shelves, mounted in roll out drawers or what? I am looking for ideas for efficient layout of the batteries and this battery box is one approach. It seems to work well except for the fact that the bottom layer of batteries would be difficult to access for maintainence.

TMT

Caught me

Yes, you caught me- 36 works fine

How will you get either 72 or 96 volts with only 8 X 6 volt batteries

- Maximum voltage POSSIBLE with this battery pack is 48.

With AGM batteries it more the heat than the hydrogen they are worried about.

Stratification of acid in AGM batteries is, AFAIK, not only not an issue, but not possible.

Mine are 2 deep, three wide in a single layer.

Interesting.

Thanks for the clarification about Class 2. I musta had at least NEC Class 2 and Class I, Division 2 all jumbled up ;-)

It would appear that the listing for the PD91x0 devices is probably UL 458 (" Chargers or charging functions incorporated into converter or inverters for use in recreational vehicles and boats, as covered by the Standard for Power Converters/Inverters and Power Converter/Inverter Systems for Land Vehicles and Marine Crafts").

For home use, they may need to be listed under UL 1012. " These requirements cover portable, stationary, and fixed power units having an input rating of 600 volts or less, direct- and alternating- current, with at least one output not marked Class 2, and that are intended to be employed in ordinary locations in accordance with the National Electrical Code, ANSI/NFPA 70." ) I dunno.

Previously I identified four sections of the code that seem to pertain:

Article 411 lighting (isolated;

0 ----------------------------------> ground (Art. 720 and 725 class 1)

Not shown are low-voltage outdoor lighting or telecomm.

Marc Marc_F_Hult

Stadium seating is generally a good access for maintenance.

This battery box I have has its batteries arranged in two groups of four with one group mounted above the other group.

How have you organized your battery box?

Are they all laid out horizontally, stacked on shelves, mounted in roll out drawers or what? I am looking for ideas for efficient layout of the batteries and this battery box is one approach. It seems to work well except for the fact that the bottom layer of batteries would be difficult to access for maintainence.

TMT

| >| >Interesting. I had no idea that you could get class 2 supplies with such | >| >high power output. Maybe I'll have to reconsider my low-voltage | distribution | >| >analysis... | >| >

| >| | >[...] | >| IMO, Key here is UL and internal transformer isolation. But I haven't probed | to | >| see whether it is specifically UL for Class 2. I am satisfied that it means | >| engineering needs. | >

| >Hmm. But if it isn't UL listed as a class 2 supply then it can't supply class | >2 circuits. Class 2 supplies have some pretty stringent requirements for | >current limiting (not just over current protection--source impedance is a | >consideration). Last time I checked the most power allowed for a class 2 | >supply in the lowest voltage range was 100VA. (At higher voltages the power | >is reduced disproportionately IIRC.) | | Interesting. | | Thanks for the clarification about Class 2. I musta had at least NEC Class 2 and | Class I, Division 2 all jumbled up ;-)

As in Class I hazardous locations?

| It would appear that the listing for the PD91x0 devices is probably UL 458 (" | Chargers or charging functions incorporated into converter or inverters for use | in recreational vehicles and boats, as covered by the Standard for Power | Converters/Inverters and Power Converter/Inverter Systems for Land Vehicles and | Marine Crafts"). | | For home use, they may need to be listed under UL 1012. " These requirements | cover portable, stationary, and fixed power units having an input rating of 600 | volts or less, direct- and alternating- current, with at least one output not | marked Class 2, and that are intended to be employed in ordinary locations in | accordance with the National Electrical Code, ANSI/NFPA 70." ) I dunno.

Perhaps. However, I just looked at the hookup instructions and it appears that the outputs are directly paralleled with the battery bank, i.e., whatever over-current protection the devices offer does not actually protect the load side. That suggests that no matter the listing the output is going to have to be treated like the output of any other battery bank which can deliver very high current, requiring, e.g., (expensive) class T fuses. And of course, the wiring at that point isn't even class 1. (I used to think that it could be class 1 subpar (b) which goes to 600V with no power limitations, but that's for signaling/control only...)

| Previously I identified four sections of the code that seem to pertain: | | Article 411 lighting (isolated;

and even maybe even NCAA Division 1 and 2 ;-)

Yes. See the ASCII circuit diagram in my previous post and at the end of this one. which I think makes this clear. Over-current protection is included.

Where do I find out about class T fuses ? Searching the 2005 draft NEC came up blank. Why do I need them? Plain old Square D QO circuit breakers are UL'd to

grounded )

Right. ABIK, it has changed and become more restrictive/ less useful. That was my point.

Outdoor wiring low-voltage wiring was separated in the 2002(?). I haven't pursued what the draft 2005 has to say. but I didn't stumble across anything that clarified how to get from one t'other or made life easier.

Yes and maybe not :-)

Yes, from the perspective that you are analyzing the benefits as if the installation is something to be commercialized -- which it is not. There is no reason why a personal endeavor ("hobby") has to be practical, or cost effective. Most of what I see folks doing in comp.home.automation (and perhaps the cross-posted NGs too) would not meet those criteria. Perhaps we need to start a rec.home.automation ;-)

Yes, from social reality that in a system with multiple, distributed components that require electrical power, the conventional approach of providing that energy with Class 2 wallwarts quickly becomes untenable. Spousal factor -- the answer to "Can I put three _more_ wall warts over here so that the open-close and tilt drapery motors and the controller can be powered?" is "No". So what to do ? One part of the answer is distributed DC power in my case.

Yes, examining the assertion that 120VAC is always standard and low-voltage is non-standard. To the extent that many of my objectives stem from, and are ultimately directed at environmental monitoring, 120 AC is very much the non-standard, not low-voltage. When was the last time you saw a AC-powered pH or conductance meter? Or weather station? Or sampling pump, or ... My backyard is

Yes, from the standpoint that you see "keeping lines separate" as a negative. We separate AC lines one from another too. Why is this a problem? Why is it not a design advantage to have independent systems? I can rip everything I've installed out and the house and household would go on jist fine, albeit with diminution of smart/automation functionality and emergency and aesthetic aspects of lighting.

Yes, from the difference that you see having to use Chapter 3 materials as a problem, whereas I see it as the cheapest way to get materials in many cases anyway. The power of Home Depotizing as it were ..

Yes, recognizing that I already have a large supply of components for DIY. Sometimes I build things just to convert "parts" into "devices" (in the spirit of rec.home.automation ;-)

Yes, from the fact that the "inherent loss disadvantages of low voltage" is eliminated completely by proportional increase in the cross-sectional areas of conductors. There are, of course, advantages to higher voltages. We converted our house in Spain from 110 to 220 3-phase which made conductors embedded in solid masonry walls much more useful. But that is not the situation in my US home. I am installing new conductors, and don't have to retrofit. The house is

And maybe *not* ;-) because you have excellent analytical abilities and apply them diligently to a confusing set of facts, boundary conditions, circumstances and regulations in a way that is very helpful to others (too).

I _greatly_ appreciate you helpful comments. You've helped to clarify, organize and correct much.

Regards ... Marc Marc_F_Hult

Not shown are low-voltage outdoor lighting or telecomm.

Yes, you were clear. I was confused by the description on the manufacturer's site. With all the talk of sophisticated over-current detection I thought the supply had to interpose some electronics between the battery string and the output. I guess the protection is just for the wires to the battery. :( In case you care, I'm pretty sure that there do exist supplies that work the way I thought these work.

| Where do I find out about class T fuses ?

A Google search seems to turn up quite a few hits. One thing I noticed is that they aren't as absurdly expensive as I remembered...

| Searching the 2005 draft NEC came up | blank. Why do I need them?

To be honest, I'm not sure you do. This came up some years ago when I added a remote battery string to a UPS. To my annoyance I found that while inexpensive 100A automotive fuses could be used for similar applications in cars, boats, mobile homes, and even internally to said UPS and its packaged expansion batteries, I had to use a class T fuse because I was running the circuit in a building. This might have been a local issue and/or I might have overreacted to some of the requirements. After getting the correct fuse I sort of stopped looking for additional problems because, well, the box I was using wasn't a listed battery enclosure and the UPS wasn't actually listed for connection to anything but their packaged expansion batteries (though at least the string I used fell within the allowable range of capacities) and so on... :)

| Plain old Square D QO circuit breakers are UL'd to | 60vdc.

As I recall, a circuit breaker with the required DC arc interrupting capacity (20kA?) and response time was even more expensive than the fuses. But since a lot of this is listing politics rather than genuine engineering it's certainly possible that a commodity device would have been acceptable and I just missed it.

| >If they have added a genuine class 2 supply requirement | >I would think that many of the existing landscape lighting transformers are | >now out of spec since even the multi-output ones typically exceeded 100VA on | >each output. It may be that there is now a specific (and different) type | >of class 2 listing for such supplies that makes this all work out. There | >is an unfortunate trend in this respect to make listings extremely application- | >specific, thus thwarting non-standard or unanticipated custom assemblies. | | Right. ABIK, it has changed and become more restrictive/ less useful. That was | my point. | | Outdoor wiring low-voltage wiring was separated in the 2002(?). I haven't | pursued what the draft 2005 has to say. but I didn't stumble across anything | that clarified how to get from one t'other or made life easier.

I just checked the Juno Flex 12 system for which I happen to have a catalog. It's one of those exposed-conductor indoor low-voltage track systems. The transformers go to 600VA per circuit, so I think even indoor systems are going to have a problem with a class 2 supply requirement. Unless those were never under 411 to begin with (like your tracks?).

| >Here's the problem I had when I looked at the whole low-voltage DC distribution | >idea a while back. Whether you classify your circuits under 720 or 725's | >class 1 you still have to use the same Chapter 3 materials and methods that | >you would use for line voltage circuits. Plus you have to keep the two | >(or maybe all three) separate. Plus you have to deal with non-standard | >(and thus more expensive) ancillary components like DC-rated switches and | >fuses. Plus you have the inherent loss disadvantages of low voltage. As | >far as I can tell, the only thing you gain under class 1 is the ability to | >use No. 16 and 18 conductors, not that I'd want to. Am I missing something? | >

| | Yes and maybe not :-) | | Yes, from the perspective that you are analyzing the benefits as if the | installation is something to be commercialized -- which it is not.

I was really trying to frame some simpler questions. What is it that you are allowed to do by remaining < 30V that you would not be allowed to do if you used, say, 48V? Similarly for using DC instead of AC.

| Yes, from social reality that in a system with multiple, distributed components | that require electrical power, the conventional approach of providing that | energy with Class 2 wallwarts quickly becomes untenable. Spousal factor -- the | answer to "Can I put three _more_ wall warts over here so that the open-close | and tilt drapery motors and the controller can be powered?" is "No". So what | to do ? One part of the answer is distributed DC power in my case.

Don't the DC/DC converters take up about as much space as the wall warts they replace? Or do you have enough consumer devices that require neither voltage conversion nor isolation nor class 2 current limitation that you come out ahead?

Dan Lanciani ddl@danlan.*com