Electrical Question

[Dane]

Since this is the best place on the net to get good advice on anything:

So I pretty fair at electrical work but I'm working on adding 120v power to my enclosed trailer.  Looking for some reinforcement that I'm not going to burn the trailer down or kill myself.  

So here is what I have in mind:

I'm going to use a 30a twist lock <This> to enter the trailer.  From there I'm going to run a 10/2 w/ground wire to run into <This>.  Now from there I'm planning to adapt the box to hold a 30 amp 2 pole <Switch> and hook both the neutral and hot to this switch.  I'm also going to wire some 120v LEDs across the hot and neutral to indicate power as well as the neutral and ground to indicate reverse polarity.  From there I'm going to run the hot wire to a 30 amp single pole <breaker> to feed the panel.  Since this is only 120v system I am going to put in a jumper across the lugs to power up the other side of the box.  

One question is should I isolate the ground and neutral from each other in the panel.  

 

Thanks! 

[Sam1]

As with all things that can cause harm to people or damage to property, I suggest you host a TGO gathering and provide lots of whiskey.  We'll figure it out.

[gun sane]

The only thing I advise is what I learned in the movies about diffusing bombs.  Don't ever cut the green wire!   Or is it the yellow one......

[bigun]

Run your 10-2 w/ ground to the 2 main lugs and that will supply power to the 4 breaker slots. No need for a 30 amp switch. to kill the power just unplug. your protection for the main will be the breaker supplying the plug in. Then just wire up the 4 breakers as normal.

 

[RED333]

10 AWG is just big enough, if you cord is over 30 feet the volt drop might give you problems, #8 would be better.

1 hour ago, Dane said:

One question is should I isolate the ground and neutral from each other in the panel.  

No, it will be OK

[Dane]

7 minutes ago, RED333 said:

10 AWG is just big enough, if you cord is over 30 feet the volt drop might give you problems, #8 would be better.

No, it will be OK

The 10AWG will be from the connector on the side of the trailer to the box,  about 4-6 ft.  The cord is one I ordered pre-made so it should be of adequate wire size for the length.  Thanks for the reply! 

[RED333]

Less than 10 feet, you are good to go.

[gjohnsoniv]

5 hours ago, gun sane said:

The only thing I advise is what I learned in the movies about diffusing bombs.  Don't ever cut the green wire!   Or is it the yellow one......

I had that experience the other day.  They said "Cut the red wire and attach to terminal 55"  

 

Me:  "Uh, that's going to be a problem..."

(Red wire here I had to add in to jumper jumper two things together, not part of the original cut conversation)

[hardknox00001]

Just out of curiosity, are you going to power anything else but some lights?  You can get 12 volt DC lights that will run off your automotive power.

[mikegideon]

6 hours ago, RED333 said:

10 AWG is just big enough, if you cord is over 30 feet the volt drop might give you problems, #8 would be better.

No, it will be OK

#10 is plenty big for a 30 amp load. Resistance is about .001 ohms per foot. 

 

[DaveTN]

13 hours ago, Dane said:

One question is should I isolate the ground and neutral from each other in the panel.  

I’m no electrician, so maybe someone here that is can answer this, but I believe, yes, they need to be isolated at a sub panel.

[mikegideon]

5 minutes ago, DaveTN said:

I’m no electrician, so maybe someone here that is can answer this, but I believe, yes, they need to be isolated at a sub panel.

They are tied together in a regular panel. But in a trailer, you may want to separate. With them isolated, equal currents will flow in the hot and the neutral, with almost no current flowing in the ground. With them tied together, the ground will carry some of the current that normally flows in the neutral. Will it matter in the real world? Probably not. I would split them. 

[DaveTN]

12 minutes ago, mikegideon said:

They are tied together in a regular panel. But in a trailer, you may want to separate. With them isolated, equal currents will flow in the hot and the neutral, with almost no current flowing in the ground. With them tied together, the ground will carry some of the current that normally flows in the neutral. Will it matter in the real world? Probably not. I would split them. 

That’s my understanding of it.

Besides the safety issue; it can also cause issues with today’s sensitive electronic equipment.

[Sunfish]

A disconnect or sub panel will work? Bigun is right about your feed.  (Temporary's have been known to last a long time)  

[Dane]

Just out of curiosity, are you going to power anything else but some lights?  You can get 12 volt DC lights that will run off your automotive power.

Currently I have a refrigerator operating in the trailer. I plan on adding some lighting and an A/C.

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[Dane]

21 hours ago, bigun said:

Run your 10-2 w/ ground to the 2 main lugs and that will supply power to the 4 breaker slots. No need for a 30 amp switch. to kill the power just unplug. your protection for the main will be the breaker supplying the plug in. Then just wire up the 4 breakers as normal.

 

Since I will not always be plugging into a box with known good power the switch is so I can check polarity and ensure a good circuit before powering my box.  Also plugging the 10/2 into the lugs without a jumper won't work since this is only a 120v system.  I have to jumper the lugs regardless of anything else to supply power to both legs of the box.  

 

[Dane]

17 hours ago, gjohnsoniv said:

I had that experience the other day.  They said "Cut the red wire and attach to terminal 55"  

 

Me:  "Uh, that's going to be a problem..."

 

(Red wire here I had to add in to jumper jumper two things together, not part of the original cut conversation)

Got to ask.... what were you working on?

 

[gjohnsoniv]

2 hours ago, Dane said:

Got to ask.... what were you working on?

 

Installing a new control panel on an old generator. Huge pain in the rear. 

Edited February 12, 2017 by gjohnsoniv

[bigun]

2 hours ago, Dane said:

Since I will not always be plugging into a box with known good power the switch is so I can check polarity and ensure a good circuit before powering my box.  Also plugging the 10/2 into the lugs without a jumper won't work since this is only a 120v system.  I have to jumper the lugs regardless of anything else to supply power to both legs of the box.  

 

Each of the main lugs should be supplying 2 breakers

[Dane]

Each of the main lugs should be supplying 2 breakers

Right, but the feed coming in is only one leg, 120v. So I only have a hot wire, neutral and ground coming in.

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[bigun]

OK got it did not know that. Yes just jump the 2 main lugs.

[Randall53]

Nobody has asked this but it's kill'n me.  What kind and size of trailer are you wiring? Also, what size is the refrigerator and AC (that's two items with compressors....surge current may play in here during startups) ? Are you going to have heat also? Remember this about the electical code book....everything in it is the minimum you can use as in wire sizes and conduit etc.... You can always go up, just never down. Within reason of course.

Edited February 14, 2017 by Randall53

[Dane]

Nobody has asked this but it's kill'n me.  What kind and size of trailer are you wiring? Also, what size is the refrigerator and AC (that's two items with compressors....surge current may play in here during startups) ? Are you going to have heat also? Remember this about the electical code book....everything in it is the minimum you can use as in wire sizes and conduit etc.... You can always go up, just never down. Within reason of course.

It is a 24' enclosed trailer Sure Trac 8.5' wide. Right now the fridge is a 14cuft residential unit. The AC is in the future so I don't have a spec on it. I'm considering when I add the AC to make it a heat pump unit as well. If not I'll go with a propane rv heater.



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[Dane]

Some pics of what this ended up.


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[mikegideon]

What's the current rating on that switch?