Exposed ends on MC4 connectors...will they deteriorate?

softdown

Ordered an oversize combiner box to accommodate possible future growth. It has two unused female MC4s and two unused male MC4s hanging out the side. Never gave it much thought really.

Now I am wondering if corrosion is a possibility? Or some other problem. This area used to be considered almost a desert. Now it rains every day. Re-considering moisture threats as a result.



These days we are being Good Samaritans and pointing more users to our host..Northern Arizona. As we should. Do not worry, I bought my MATE and other items, I think, from them. Tried to buy some panels but shipping wasn't working out in my favor due to panel size and small quantity.

Apples

If you have a way of measuring each of the two connectors that comprise a complete MC4 connection (there are two different overall diameters involved), you may be able to find at your local auto parts store an assortment of rubber vaccum line/vacuum fitting caps.

Sure, for duplicates of the sizes you need you may have to spend more than you'd like to on such a seemingly-trivial endevour, however it really is the only option at this point because you don't want to use electrical tape (adhesive residue) or any silicone/dielectric grease (meant for lubricating dissimilar materials' connections but not for electrical contacts per se).

Photowhit

Why not plug your unused male and female together?

softdown

Thinking I tried this and it created a short. I know I tried it. Not sure if that blew all my fuses in the small combiner boxes dumping into the big combiner box.

I was stretching my abilities a bit when I wired it up. Hired a pro for the last few connections in fact. To play it safe and save my stuff.

Photowhit wrote: »

Why not plug your unused male and female together?

littleharbor2

Or you could buy some MC-4 connectors and plug them onto your exposed ones They are about a buck a pair on ebay.

softdown

That is what I wound up doing. Made in China and I hate that. But should do the job of keeping out the elements without leaving a residue.

Every day I reminisce about what It felt like to be able to buy Made In America just as easily as Japan or Korea or Taiwan. China, Vietnam, and India are manufacturing black holes but that is another story. I'm not going bankrupt trying to stave off the inevitable.

littleharbor2 wrote: »

Or you could buy some MC-4 connectors and plug them onto your exposed ones They are about a buck a pair on ebay.

Photowhit

softdown wrote: »

Thinking I tried this and it created a short. I know I tried it. Not sure if that blew all my fuses in the small combiner boxes dumping into the big combiner box.

I was stretching my abilities a bit when I wired it up. Hired a pro for the last few connections in fact. To play it safe and save my stuff.

I really can't see this happening. Unless someone sold you some extra fuses. You just don't add fuses or breakers if you aren't using them... There should be nothing connected on the inside of the box/other end of the wire...

cupcake

softdown wrote: »

That is what I wound up doing. Made in China and I hate that. But should do the job of keeping out the elements without leaving a residue.

Every day I reminisce about what It felt like to be able to buy Made In America just as easily as Japan or Korea or Taiwan. China, Vietnam, and India are manufacturing black holes but that is another story. I'm not going bankrupt trying to stave off the inevitable.

Americans are 'too good' to work factory jobs, and too cheap to spend on quality products - thus 'made in china'. 99% of panels are simply China-panels these days... its just a fact... there is high-end chinese stuff, but like everything of quality - it comes with a cost... People complain about 'made in china' while at the same time refusing to pay TRIPLE THE PRICE for a quality product...

2centz

softdown

Americans will work factory jobs adequately as a rule. The regulations and red tape shut us down as well as the fact that the Chinese work for a fraction.

We were able to compete with Japan, Korea, and Taiwan. Chinese labor is a whole new world.

cupcake wrote: »

Americans are 'too good' to work factory jobs, and too cheap to spend on quality products - thus 'made in china'. 99% of panels are simply China-panels these days... its just a fact... there is high-end chinese stuff, but like everything of quality - it comes with a cost... People complain about 'made in china' while at the same time refusing to pay TRIPLE THE PRICE for a quality product...

2centz

softdown

Wish I could remember every detail. I tried it and it didn't work out with my system. Thought it would for sure. Memory of blown fuses is so hazy that there is a good chance it never happened.

My combiner box set-up is a bit unique. I have four small boxes feeding into one large box. With room for two more small boxes.

I thought it would work. On paper....the idea looked sound.

Photowhit wrote: »

I really can't see this happening. Unless someone sold you some extra fuses. You just don't add fuses or breakers if you aren't using them... There should be nothing connected on the inside of the box/other end of the wire...

BB.

Just a caution... "We" are used to working on electrical wiring systems that have a single power source (such as utility power, genset, battery bank, etc.)... However, with solar, we typically have multiple power sources (parallel strings of solar panels, Battery Bank+Genset+AC inverter-charger, etc.). Multiple power source electrical wiring (such as your main DC bus) are a bit more complex/different than people first expect when trying to design "something safe".

For example, the maximum current on a common battery bus is the Battery Bank + Backup AC battery Charger + Solar Charger--So that "common point" on the bus now has the sum of three (or more) current sources (each may have a 100 amp breaker, but the bus+local wiring has 300 amps of current available).

Another gotcha is the question of grounding the Battery bank negative terminal. It turns out that most people use a single circuit breaker on each "hot" (usually positive) wire of the battery bus. It turns out, that if you do not "hard ground" the DC return (typically negative) bus to the metal of the RV, that the a pair of short circuits (say one in the negative lead in a light fixture) and a second in the positive lead to the AC inverter)--That you can burn out your wiring and start a fire in the light fixture return current path (no fuse/breaker).

People like "floating" (non-grounded) battery power systems--And for the "first short" they are fine. However, floating systems with one short are no longer floating (and most systems will run fine with one short)--Setting you up for a very hazardous set of conditions if you ever get a "second short"--In industry, floating power systems typically have double pole breakers (breaker on + and - or hot and return) to prevent such failures from happening. And on the "rare" floating power systems, they usually have some sort of method of detecting a short to ground (this is what the newer NEC codes require for solar arrays and DC power systems).

For solar, some of the "middle age" regulations are actually very dangerous--And the ground fault detection is either poorly designed (really unsafe) and/or "overly sensitive" (Arc Fault type breakers is another "problem")... Grounding and safety is a major concern with us here. And why some of the suggestions "sound cook book" (do this, don't ask why unless you like long boring technical explanations). And why the NEC has so many rules--If you follow them correctly, it prevents secondary issues/complexities from causing you grief. But it can also make a system more expensive and complex (not everyone can afford/fit $100's for heavy wiring/sets of circuit breakers).

It is a risk/reward set of decisions. We will try to keep everyone safe, but each is responsible for their choices.

-Bill

cupcake

softdown wrote: »

Americans will work factory jobs adequately as a rule. The regulations and red tape shut us down as well as the fact that the Chinese work for a fraction.

We were able to compete with Japan, Korea, and Taiwan. Chinese labor is a whole new world.

Here's something you should know: cheap labor and cheap consumers are RECIPROCALS.
That means, cheap chinese labor only came when cheap american consumers demanded cheap goods... Everyone on this forum knows that a good inverter like a Mornigstar MPPT (Made in Tawain, not China) costs about $600 and up. However there are MANY cheap chinese inverters for only $99. This is what the [american] market demands...

Americans want cheap stuff, so to meet that demand cheap labor is used, thus American manufacturing is lost... 2cent