shore power contection

[HighTechRedneck]

Bob, I didn't mean to shoot down you morale.  As all the others have said, you have done amazing things already.  I know a complete AC rewire sounds daunting, but as Dallas pointed out, the presence of conduits helps.  I wish I was closer, I would help you with it.  But rewiring will be one of the easier tasks you are dealing with.  To do a good job on it just takes a little patience and self discipline.  A helper at the other end of the wire can make things easier but you can do it by yourself if needed.

You can do it!  Look at all the cheerleaders that are here for you! (granted, ugly cheerleaders, but we're full of pep or something  )

[Sean]

Bob,

Just to amplify/clarify some items:

Looking at the transfer switch, it's clear to me what's been done.  Whoever wired things tried to save a bit of money, and used three-conductor SO cable (the stuff with the black rubber jacket) to wire 240-volts instead of the correct, four-conductor cable.  It looks like they chose to use the green wire for neutral, and the black and white wires for the two hots.

This is the key problem you need to correct.  The issue of the unsafe color code aside, there is also no ground wire in this arrangement.  So your first step should be to remove the three-conductor cable, and replace it.  Since it looks like you have conduit there already, I would replace the cable with individual THHN wires.  You'll need black, red, white, and green.

I can't tell from the photo what gauge was used.  But for 50 amps, you need to use #6.  It looks to me like what's there may be as small as #10.  This is another big problem that you will solve by replacing the SO cable.

As far as the distribution panel goes, yes, it needs clean-up, but I've seen worse.  One thing you can do without having to tear out mis-colored wires is to get yourself some colored electrician's tape in black, red, white, and green.  The code allows you to mark wires with an inch or so of colored tape at each end.

With all due deference to HighTechRedneck, blue is an allowable color for hot wires.  In fact, my system uses three hots from the ATS to the main panel, and I've chosen black, red, and blue (only two of the three can be energized at once).  But green must always be ground, and white must always be neutral.

The transfer switch common-gang wiring also looks to me to be too small -- when you replace the SO, I would also make sure these three wires are #6, and properly color-coded.  It's hard to tell from the photo what the ampacity of those contactors is.  If you want a 50-amp coach, and you replace the SO with #6, you should make sure the ATS is also up to the task.  If it's a 30-amp model, change it out.  The alternative is to protect the whole shebang with 30-amp breakers upstream of the ATS.  That would, of course, limit you to using only 7,200 watts of your 14,000 watt generator.

The main feed to the distribution panel (which you will replace based on my first recommendation, above) looks to be going in to a 100-amp two-pole breaker.  You need to replace this breaker with a 50-amp (or 30-amp, if you chose to go that route) model.  About $15.

Lastly, the Marinco 50-amp, 240/120-volt shore power inlet you have described is a perfectly acceptable way to connect your shore cord to the coach.  In fact, this is a common arrangement and shore power cables which mate with this connector are available off-the-shelf.

Keep the faith -- you'll get there.

-Sean
http://ourodyssey.blogspot.com

[Dallas]

Bob,

Just to amplify/clarify some items:

Looking at the transfer switch, it's clear to me what's been done.  Whoever wired things tried to save a bit of money, and used three-conductor SO cable (the stuff with the black rubber jacket) to wire 240-volts instead of the correct, four-conductor cable.  It looks like they chose to use the green wire for neutral, and the black and white wires for the two hots.

This is the key problem you need to correct.  The issue of the unsafe color code aside, there is also no ground wire in this arrangement.  So your first step should be to remove the three-conductor cable, and replace it.  Since it looks like you have conduit there already, I would replace the cable with individual THHN wires.  You'll need black, red, white, and green.

I can't tell from the photo what gauge was used.  But for 50 amps, you need to use #6.  It looks to me like what's there may be as small as #10.  This is another big problem that you will solve by replacing the SO cable.

As far as the distribution panel goes, yes, it needs clean-up, but I've seen worse.  One thing you can do without having to tear out mis-colored wires is to get yourself some colored electrician's tape in black, red, white, and green.  The code allows you to mark wires with an inch or so of colored tape at each end.

With all due deference to HighTechRedneck, blue is an allowable color for hot wires.  In fact, my system uses three hots from the ATS to the main panel, and I've chosen black, red, and blue (only two of the three can be energized at once).  But green must always be ground, and white must always be neutral.

The transfer switch common-gang wiring also looks to me to be too small -- when you replace the SO, I would also make sure these three wires are #6, and properly color-coded.  It's hard to tell from the photo what the ampacity of those contactors is.  If you want a 50-amp coach, and you replace the SO with #6, you should make sure the ATS is also up to the task.  If it's a 30-amp model, change it out.  The alternative is to protect the whole shebang with 30-amp breakers upstream of the ATS.  That would, of course, limit you to using only 7,200 watts of your 14,000 watt generator.

The main feed to the distribution panel (which you will replace based on my first recommendation, above) looks to be going in to a 100-amp two-pole breaker.  You need to replace this breaker with a 50-amp (or 30-amp, if you chose to go that route) model.  About $15.

Lastly, the Marinco 50-amp, 240/120-volt shore power inlet you have described is a perfectly acceptable way to connect your shore cord to the coach.  In fact, this is a common arrangement and shore power cables which mate with this connector are available off-the-shelf.

Keep the faith -- you'll get there.

-Sean
http://ourodyssey.blogspot.com

And There Bob, You have heard from one of the people I most respect in this undertaking.

Go for it, or as the Marines are wont to say, Improvise, Adapt, Overcome!..... Just don't improvise too much.

Dallas.

PS: It's not often I take this much interest in a project of the magnitude you have going, but this one is so full of opportunity to make it better than it ever was before. You are going to have one great conversion there. Keep a stiff upper lip and a song in your heart.

DF
30

[Sam 4106]

Hi Sean,
According to my old chart you can use 4 #8 THHN wires for 50 amps in 3/4" conduit exposed to open air. It would require 1" conduit for 4 #6 THHN wires. I can't tell what size conduit is there now, but if it is 3/4" he would have to change to 1" for 4 #6 wires. My chart is based on the 1993 NEC so it may not be valid anymore.

My guess is that the transfer switch is rated for 50 amps since it has 3 pole contactors, only 2 pole contactors would be needed for 30 amps. But, what do I know?

I see many thing wrong with the wiring in Bob's bus and it was obviously not done by a professional. However, with help from the members of this board I'm sure it can be corrected.

Thanks, Sam 4106

[Len Silva]

Bob,

There are just so many wiring problems I see from just two pictures you posted that I think a complete rewiring job is in order.  Don't let that throw you, it's not that big a deal, just a new learning curve if you are not knowledgeable in that area.

Hard to tell but it looks like the lower left breaker is rated at 100 amps but the wire feeding it is no where near large enough.

Some of the wiring is in pipe but it appears to be thin wall pvc water pipe, not electrical conduit and not properly connected to the box.

Just as in the bus wiring, it might be simpler to just rewire rather than try to figure out what those before you might have done.
Good luck, wish I was close enough to help.

Len

[Sean]

And There Bob, You have heard from one of the people I most respect in this undertaking.

Thanks, Dallas.  It's nice to feel appreciated.

According to my old chart you can use 4 #8 THHN wires for 50 amps in 3/4" conduit exposed to open air. It would require 1" conduit for 4 #6 THHN wires. I can't tell what size conduit is there now, but if it is 3/4" he would have to change to 1" for 4 #6 wires. My chart is based on the 1993 NEC so it may not be valid anymore.

Sam, I'm sorry to say that one of the things I no longer have room for on the bus is the enormous NEC handbook which I used extensively during my conversion.  So I ditched it.  I worked from the '99 code, which was in force when I started.  When I ran the numbers, I came up with #6 for 50 amps based on the required deratings for fill.  I would not go less than that, although #8 is fine when run "free in air" (a really theoretical number, since, aside from overhead power distribution lines, nothing is ever permitted to be run free in air).  Most of the charts I have agree with this.

Remember that the NEC itself does not specify minimum wire gauge for any application -- it merely states an upper limit on ampacity based on insulation type (e.g. THHN, THNN), raceway fill, and other factors.  It's up to the engineer/installer to do the right math.

My guess is that the transfer switch is rated for 50 amps since it has 3 pole contactors, only 2 pole contactors would be needed for 30 amps. But, what do I know?

Well, if it was purchased from an RV dealer for RV applications, you are right.  But there are three-wire (240/120-volt) transfer switches rated at 30-amps, because that is a common size for residential backup power use.  So just the number of poles alone is not a sufficient indicator of the rating of the switch.

The entire assembly, as a transfer switch, should be rated and marked either on the cover or somewhere inside the box.  Beyond that, the three-phase reversing motor starter upon which the ATS is based (what those three-pole contactors are really made for) will have a rating stamped on it someplace, but it may be in HP, or so many amps each for IE-1, -2, -3, and -4 usage.  In order to translate that into a rating for ATS use in a single-phase, mixed-use, mostly-resistive application, you need to do some conversions.

Given how sloppy the rest of the electrical work is, and how many corners were cut to save a penny, I can't rule out the possibility that the installer used a 30-amp model where a 50- was really called for.  They are widely available.

Hard to tell but it looks like the lower left breaker is rated at 100 amps but the wire feeding it is no where near large enough.

Is there an echo in here? 

-Sean
http://ourodyssey.blogspot.com

[Len Silva]

Hard to tell but it looks like the lower left breaker is rated at 100 amps but the wire feeding it is no where near large enough.

Is there an echo in here? 

-Sean
http://ourodyssey.blogspot.com

Not the first time I stuck my nose into a conversation without listening to what everyone else was saying.

[Bob Gil]

does this nean it is wired right?

3 to the switch and one to ground?

[Bob Gil]

picture 2

[Bob Gil]

bottom of the diagram on switch

[Bob Gil]

i do see they did not use the same colors as the diagram.

[Nick Badame Refrig/ACC]

Hi Bob,

This is wired for 30 amp and is correct. Is this what your trying to find out?

If it were 50 amp, your green wires would be connected to the grounding block in the box and a White nutral would be where your

green ground is now along with a Red on L2.

Hope this helps
Nick-

[Nick Badame Refrig/ACC]

Bob,

All your diagrams are for 50 amp.. So, NO, you are not wired correctly if you are thinking 50amp..

Just 30amp.

Nick-

[Sean]

This is wired for 30 amp and is correct. ...
If it were 50 amp, your green wires would be connected to the grounding block in the box and a White nutral would be where your
green ground is now along with a Red on L2.

Nick, I beg to differ with you.

That's what it would seem from the colors.  However, if you go back to the original photos in his earlier posts, you will see that

• The black wire feeds one side of a 100-amp, 240-volt, two-pole breaker.
• The white wire feeds the other pole of that same breaker. (!!!)
• The green wire is feeding the neutral bus.
• The application is 240-volts.

As I wrote in my earlier post, what has apparently happened here is someone cheated and used xx/3 SO to wire 240-volts, and omitted the ground.  The colors are dangerously wrong.

Bob:  Yes, you should rewire the switch according to the color code indicated on the diagram.  As I wrote earlier, use #6 THHN wire if you intend to carry 50 amps.

-Sean
http://ourodyssey.blogspot.com

[Bob Gil]

I think they had tried to wire it right but used the wrong colors and grounded it at the other end of the cord where is cam into the bus.  I found the other end of the 3 wire #6 and it had a 4th wire wraped around it going to the frame of the bus.


What is THHN wire?