# Standard DC connectors?



## cowboy joe (Sep 14, 2003)

Well, the last of the parts for the charging system are on their way so I hope to finish off the small PV system I'm installing within the next few weeks. As I thought about the location for a few outlets throughout the house, it dawned on me that I had never heard of a standard connector for DC systems. Through my involvement with amateur radio, I know that the Anderson Powerpole is the defacto standard in the ham world:

http://www.powerwerx.com/anderson-powerpoles/

These are well made & very durable even if they are a bit on the pricey side. My radios all use a common molex connector for external power so I made an adapter harness in case I ever needed to connect to a powerpole connector.

I spent time on a google search & still have no real answers. Seems everyone is off doing their own thing:

http://en.wikipedia.org/wiki/DC_connector

So, after all that, the questions remain:

1. Is there a 'standard' connector or one that is generally used for the majority of installations?

2. If not, what are your suggestions?

Each outlet will have its' own fuse/breaker which will limit the current to 5A. The current system has a single 45W panel which will be used to charge two or three 12V, 16AH sealed, lead acid batteries for a total of 32-48AH which should be ample to run a work light (occasional use) & a pair of small muffin fans to vent the heat (to the outside in the summer & the inside of the house during the cooler months) in the greenhouse, an outlet in the main living area of the house for a light during power outages, plus an outlet to charge a radios, cellphones, etc.. The pair of muffin fans draw a combined current ~250mA and typically run only when the sun is out as they are wired to a thermostatic control. 

I also have a small wattage inverter that will be fitted an adapter to the power system should a minimal amount of AC ever be required and a homebrewed charger / power source with various outputs to allow charging of cell phones, NiCads, NIMH, & SLAs. I'm thinking the 48AH battery capacity is over kill as the system should have no problem keeping those fully charged, especially with the light load. But since this is my first go at a PV system, I'm learning as I go or at least trying to. As always, any / all advice or comments humbly appreciated. Thanks in advance.


----------



## 12vman (Feb 17, 2004)

I don't really know what's "standard" but I use a lot of these..

14.0553










As long as you stay under 4 amps per outlet, you won't have any problems. The complete outlet has a 15 amp breaker built into it that will reset after it cools down and the short is removed. I've been using these for years with no problems.


----------



## wy_white_wolf (Oct 14, 2004)

TMK (and I may be wrong) you can get regular oulets that do have both an AC and DC rating and code allows there use as DC plugs as long as they are a different style of outlet than any AC used in the premise. The standard 110VAC 2-3 prong is never allowed though even if AC is not used on the premise.

I'm trying to find the write-up on this where they used what is normally a 220VAC 20amp outlet for all the DC outlets. All DC oulets also had to be marked as to the affect. Just can't remember were I saw it.

What 12vman posted does not pass any code and can get you in trouble with the insurance company for using them.


----------



## 12vman (Feb 17, 2004)

"What 12vman posted does not pass any code and can get you in trouble with the insurance company for using them."

Is there actually a code for low voltage? If there is, please produce a link.


----------



## cowboy joe (Sep 14, 2003)

I did a search on NEC & photovoltaic systems and came up with this:

http://www.re.sandia.gov/en/ti/tu/Copy of NEC2000.pdf

Haven't had a chance to review the entire doc yet (117 pages). Also recognizing the fact that it is "Suggested practices" & not actual mandated codes. However, the text states that the use of the words 'must' or 'shall' does refers to actual requirements of the NEC / NFPA code.

Here's the section on DC Outlets:

"The receptacles used for dc must be different than those used for any other
service in the system [210-7f, 551-20f]. The receptacles should have a rating of not less than 15 amps and must be of the three-prong grounding type [210-7a, 720-6]. Numerous different styles of listed receptacles are available that meet this requirement. These requirements can be met in most locations by using the threeconductor 15-, 20-, or 30-amp 240-volt NEMA style 6-15, 6-20, 6-30 receptacles for the 12-volt dc outlets. If 24-volt dc is also used, the NEMA 125-volt locking connectors, style L5-15 or L5-20, are commonly available. The NEMA FSL-1 is a locking 30-amp 28-volt dc connector, but its availability is limited. Figure 22 shows some of the available configurations. Cigarette lighter sockets and plugs
frequently found on âPVâ and âRVâ appliances do not meet the requirements of
the National Electrical Code and should not be used."

Still need to review in detail. Good reference material if nothing else.


----------



## wy_white_wolf (Oct 14, 2004)

Joe

You might want to replace that one with this one. It's dated 2005 instead of 2001. Not sure what changes they may have made

http://www.nmsu.edu/~tdi/Photovoltaics/Codes-Stds/PVnecSugPract.html


----------



## 12vman (Feb 17, 2004)

"Cigarette lighter sockets and plugs frequently found on &#8220;PV&#8221; and &#8220;RV&#8221; appliances do not meet the requirements of the National Electrical Code and should not be used."

Isn't it amazing how many products are sold with such a connector..

"The receptacles used for dc must be different than those used for any other service in the system"

Let's see ya plug a toaster into a cigarette lighter jack... LOL Kinda contradicting..

It's NOT OK to use a cigarette lighter jack to operate a small appliance but it's OK to ram a cigarette lighter in one that draws 10-15 amps.. Go figure..


----------



## cowboy joe (Sep 14, 2003)

Thanks for the link Wolf. My sense is the NEC isn't certain what to do yet as PV / wind systems, while not new, were really low volume in years past. Have to believe the manufacturers will start to line up, trying to make their connector the 'standard' as DC installations proliferate. 

I look through parts manuals over the weekend to see if I could find a decent, inexpensive connector type. Biggest problem is most of the panel mounts for the DC connector pairs are male which would be a big no-no as the contacts are exposed. At minimum, the supply connector must not allow accidental contact with a live voltage source so typically the outlet is female.

No hurry I suppose. Just got an e-mail and my parts won't be here until Sept 8. Moved all the location of the charger / batteries / distribution this weekend to a better location. Everything was kind of third world engineered anyway with all the testing I was doing during the charger design. Good opportunity to clean up the install, make room for all the pieces and ensure the system is up to snuff code wise. A bit confused over the ground requirements so I'll need to go back & figure out the connection & the lightening suppression (roof mounted panels).


----------



## Jim-mi (May 15, 2002)

That cig lighter plug is intended for very short intermittent usage with time to cool off before being used again.

A constant heavy load will make it dangerously hot.

Also the contacts are poor and so in time will create a very high resistance connection which will cause even more HEAT.

Leave the ciggie plugs in the cars................


----------



## 12vman (Feb 17, 2004)

Quote..
*"A constant heavy load will make it dangerously hot."*

I agree with this statement and that's the key. For any load under 4 amps, they can be used constantly without any issues. I've been opeating this computer for the last 8 yrs. on one and it draws around 50 watts at times and I've never had any problems. I operate fans, radios, my TV, amplified speakers, CD players, all kinds of "Light Loads" with no issues. It's a common connector and the polarity issue is easy to figure out.

Rule of thumb.. Any load over 4 amps, use a different type of connection.


----------



## GREENCOUNTYPETE (Jul 25, 2006)

there really does need to be a standard 12 and 24 lot dc connector that is not also used as a AC conector 

but like you found most call for a designated 20 amp 120ac outlet like you would find on a sump pump or comercial apliances


----------



## cowboy joe (Sep 14, 2003)

Learning alot researching this one. Homepower addressed the issue a few years back:

http://www.homepower.com/view/?file=HP111_pg106_WordPower

The article doesn't say much other than there isn't a standard but needs to be.

I did find these Hubbell twist locks at All Electronics:

http://www.allelectronics.com/make-...WIST-LOCK-CONNECTOR-CHASSIS-MT.-FEMALE/1.html

Different enough that you can't plug an AC device in a DC outlet & vice versa. Inexpensive, at least second hand, that they won't break the bank. These are still made and seem to be fairly common so they'll probably be around from a bit. They aren't DC rated, then again nothing I looked at was. Wonder what the building inspectors do when they have to inspect an installation. 

The cigarette lighters are the only ones that have a DC rating but again, they have exposed contacts. All the other devices I looked at were mad expensive. The least expensive were the duplex outlets with the sideways prongs (6-20R & 6-15R). Lowes carries the outlets for ~$5 each. The plugs were around the same price. Might be the best way to go.


----------



## Corwyn (Sep 7, 2009)

cowboy joe said:


> Learning alot researching this one. Homepower addressed the issue a few years back:
> 
> http://www.homepower.com/view/?file=HP111_pg106_WordPower
> 
> The article doesn't say much other than there isn't a standard but needs to be.


Seems to me that now is the perfect time for someone knowledgeable (like Home Power, or someone here) to _pick_ a standard, and promulgate it. Perhaps one plug for 12v and one for 24v? Otherwise we are stuck with no standard or a proprietary one, or the wrong one.

Anyone want to take on the challenge?


Thank You Kindly,

Corwyn


----------



## fantasymaker (Aug 28, 2005)

Jim-mi said:


> That cig lighter plug is intended for very short intermittent usage with time to cool off before being used again.
> 
> A constant heavy load will make it dangerously hot.
> 
> ...


In the trucking world these are pretty much the standard, Im not a expert on long term use but I have picked up 10 year old trucks where the owner didnt know if the appliances unplugged or not . Im pretty sure they had been plugged in thru a cig type plug for at least 10 years. 
Id say thats long enough usage for most things


----------



## Jim-mi (May 15, 2002)

That all depends on the load that has been drawn on those plugs.

Anybody who has been installing DC systems for a while will highly discourage going any where near ciggy plugs/sockets.

If any of the big boys (equipment mano's) had determined that there was a 'market' for DC plugs and sockets they would have jumped on the band wagon long ago. To them its a 'nitch' market.
Thats why any 'good' dc plugs that are on the market today are pricey . . . .very small demand.


----------

