Good evening guys and I hope you all can help me. I have gleaned a wealth of knowledge so far but have come here for the advice from people that know RV's.Story .... Moving into an RV for 4 months whilst house sells.Have an OLD Barn / Shed building which has power 200ft from main building, however, was wired ages ago and hence only has an old breaker panel with 3 feeds 2 Hots and a Neutral/Ground. This panel runs off the main, so I suppose by old standards would be called a sub main. By today's standards should be a sub panel, however, it has no Ground Poles around the barn, hence not really a sub panel and not to current code. All the grounds / neutrals for the lights and sockets in the panel for the barn are joined together into the one bar at the bottom of my Sqaure D Panel.I am moving an Travel Trailer in there next week and have to get the electrics sorted this week. I spoke to 2 electricians and both explained that what I had was NOT uncommon and what they did in Those Days. After much reading and research I asked should I strip the old panel out, and purchase a Sub panel with separate neutral and ground bars, sink 2 8ft ground rods to spec for the new box, and rewire all the grounds and neutrals to the new box. i.e. neutral bus isolated from grounds and old grounds would be tied to box and 2 new 8ft ground rods.They both said that this was unnecessary, AS LONG AS I was sure that the neutral bus bar was in good condition and that I was sure that the wiring in my USED trailer was in good condition. I understand that with codes and safety now it is required to provide a separate ground circuit at a sub panel, however, being as old as the barn is, would it be possible or sensible at all to wire the trailer up, once all checks made to existing wiring, to my existing barn panel as it stands just now.I'm running way over budget for this project and need to know what I have to do and what is possible. Safety is paramount ! I will do what I have to do but am getting confused with what electricians say and what I have taught and know myself and what I have researched.Your advice would be most welcome guys.Use existing Panel .. or complete rewire ?Just had 4 truckloads of gravel laid for the trailer, going through my orientation next week and delivery withing 1.5 weeks. Background....Mechanic by trade, good overall knowledge of electricity and wiring.Don't like doing things in halfs, don't complete projects or DIY unless researched to death and 110% comfortable !PS. This is my First RV / Travel TrailerPPS. Thanks in advance for any replies

Buy a ground buss from your local hardware store.Drill and tap the box to mount it. Do not use sheet metal type screws.Drive the two ground rods 6 feet apart.Install the correct sized and type of breaker for your rig.Install the proper receptacle for your rig.

@ enblethan, Perfect, I had come to much the same conclusion. Will need to check integrity of Neutral Buss to case ensuring no continuity, will need to ensure main breaker at house functioning for disconnect before rewire, intend to disable / disconnect everything other than 1 light in shed and 1 receptacle, have 30 amp breaker free for hot power and organizing proper receptacles and have 10/3 UF wire ready to go (XS from a Well rewire). Wiring to receptacle for trailer <25ft (estimate 18.5). Will ensure stainless steel self tappers used for ground buss bar if not supplied (Paint removed at contact point, Continuity tested before live phase). Initial connect to 1st ground should be <6ft from box. Using 6 Gauge copper for ground (unbroken to 2nd). Hopefully that should cover it ! Thank you for your reply and information Sir !

If I understand correctly you've got a 3 wire feed from the panel in your house to the one in the barn. 2 hots, 1 neutral, no ground. This is perfectly acceptable and was allowed by code until recently. However, this arrangement was always required to have a ground rod or two at the barn. There was never a time where it was allowed by code without ground rods.There's no reasons to worry about the lack of a ground wire from the main panel. Just drive your two ground rods and hook the wire to your existing neutral bar. Make sure the neutral bar is bonded to the metal can of the panel.If your neutral and ground are not bonded in the barn panel you really don't have a ground that will clear a fault.Install the proper outlet and plug in the camper. It will work fine.

KD4UPL wrote:If I understand correctly you've got a 3 wire feed from the panel in your house to the one in the barn. 2 hots, 1 neutral, no ground. This is perfectly acceptable and was allowed by code until recently. However, this arrangement was always required to have a ground rod or two at the barn. There was never a time where it was allowed by code without ground rods.There's no reasons to worry about the lack of a ground wire from the main panel. Just drive your two ground rods and hook the wire to your existing neutral bar. Make sure the neutral bar is bonded to the metal can of the panel.If your neutral and ground are not bonded in the barn panel you really don't have a ground that will clear a fault.Install the proper outlet and plug in the camper. It will work fine.x2Dusty

You cannot connect ground and neutral together at two locations. The neutral at the sub panel location must be insulated/isolated from ground.

Confused about wiring my Recent Purchase | Good Sam Community

27 Replies

jxjcksn
Explorer
Mar 30, 2014
Well sorry for late reply but a final post after all your help only seemed fitting and a THANK YOU ! for all that contributed their advice.

Code "Back then !" and Code now are obviously different, however, safety is what we were shooting for and I think we got there.

I was fortunate enough to run into a School District Electrician who I ran all this by and in short he agreed with the direction we decided on. Obviously alot of the final decisions were based on my situation regarding 3 Wire Feed / No Contact in Ground back to Main building and Age Old Wiring, but in the end the answer was to sink the 2 Ground rods per spec and Bond the Box.

Quoted ...
"Bond the neutral to the box. Run a ground outside to a ground rod, two
is even better. Place the second out further from the building at least
6' past the first. This always better moisture penetration and provides
a better ground path. Just use one piece of wire and feed thru the
first rod to the next. You are wiring it the way we used to 12+ years
ago. Nothing wrong with that. Hope that helps."

Many thanks all ... I fired her up after quadruple checking my TT30 wiring and after confirming all readings with a multimeter and socket tester.

Everything is working as intended and safely.

I hope this thread will help others in situations similar, my advice being... gather as much information as possible, Never guess what "WAS DONE" or what people say "WAS INSTALLED." Dig / pull apart / dismantle, until you KNOW what you have. Then ask questions and make decisions !

Ultimately, the responsibility is solely yours along with your safety.

Thanks again all for the contributions.

Now if the damn rain would just stop and Spring would start I could get moved in to the RV lol !
Harvey51
Explorer
Mar 24, 2014
Bonding. I ran into this when wiring up my garage. My Canadian code book says "in every case the neutral must be grounded at every building". Only one ten foot rod is required. I went to the hardware store and was told everybody uses grounding plates instead of rods now. Much easier than pounding a ten foot rod in without hitting a rock.

I asked a few people why the grounding rod and bonding are desirable for a separate building but not for a sub box in the same building. The only thing I got that made sense was that somebody digging might cut into the power line to the out building and sever just the neutral and ground wires, leaving every outlet box floating at 120 V. Somewhere on the web it mentions this is particularly annoying in Britain where every metal thing like bannisters in public buildings must be connected to the electrical ground - and they float at 240 V if the neutral + earth ground is cut while some appliance is connecting hot to neutral.

My current problem is that an electrician just wired our new 14x25 foot sun room/porch with all 8 outlets on one circuit. This meets code but seems crazy to me. Do I break this up using a second breaker or let it go? The two outdoor outlets (under 10 foot roof overhang for patio) are on one circuit, too. I don't want to call him back - he already charged $1000 labour to do it and will be back to hook up the plug ins and light fixtures after the drywall is done. He says the inspector takes at least a year to show up. Wish I had done the whole job myself.
enblethen
Nomad
Mar 20, 2014
Make sure you coat the aluminum conductors with a good coating of electrical de-oxidation grease.
Triple check your 30TT wiring before plugging in the rig!
I would say you are correct it would be through the neutral. It doesn't take much grounding on the wet side to eliminate the tingling.
jxjcksn
Explorer
Mar 20, 2014
Not an expert on wire, but if colors have anything to do with it, the three feeder wires going into my new box are silver in color. Presuming that is aluminum.

And from my basic understanding I agree with you Enblethan in the fact that bonding creates possible load current to ground especially on the grounding rods I sunk. This would not be a problem in a 4 wire system in a detached building - Simple - No bond - Neutral back to Main Supply - Ground to Detached Sunk Ground Rods - hence no Return load on the Ground wire at all.

However - 3 wire system - Pain in the Ass - Old Skool - Only path back to Main Panel is Neutral - No Conduit / Water / Gas Pipes to use !!
NOW I understand why they did NOT bond the panel as potential shorts could make the panel live AND why they joined the ground to neutral, since any N-G or L-N shorts still had a valid path to the main box, however, considering I found several faults I the wiring I am quite confident that any tool usage failure would have resulted in a considerable jolt.

Well I think we flogged this one to death gentlemen. Thanks for all the input.

In the end, since I'm rewiring the whole damn thing, the only wiring I have to worry about is the RV which I will be testing this coming Saturday on my walkthrough with the dealer, and I'll hit all the receptacles with a tester to ensure RV is 100%. I only have 2 receptacles in the barn to worry about and they have been tested AOK. I'm wiring the TT30 myself so that will be 100%.

Although this whole scenario is a hodge podge of 20 year old wiring I just have to ensure NO shorts or electrical failures. If there are any internal usage failures of equipment, I just have to ensure that it has a valid / least resistance path to follow.

Last question then before I wire the mess up !

In a path of Least Resistance Scenario .... If there was to be a short from Live to "Whatever" ..... and I have a BONDED Panel with Paths to the Main Panel Neutral and 2 Ground Rods .... Which would the current take ?

My Answer (Give or take Resistance based on Soil Moisture / Wire Resistance / Distance / Quality to the Main Panel / The fact that all sockets seem to work in the barn without tingle / tripping) would be ..
The Neutral to the Main Box would still offer the path of least resistance !

Agree / Disagree ?

And after this and any answers I think I'm done lol !
I'll post my final wiring and results once I get settled and sorted.

I have 4 yards of Gravel to rake and compact this weekend. Really looking forward to that lol !
enblethen
Nomad
Mar 19, 2014
I always was told and taught not to bond the neutral and ground at sub-panels as that puts some of the load on the ground. As I noted this was change in the 2005 NEC.
I do not know what kind of wire, aluminum or copper that is buried on your place. If aluminum there is always a chance of corrosion causing open neutrals. Copper is less susceptible to this.
On your side of the state, the ground will be far better then here. I think if your wire is aluminum, bond the system. If copper don't.
jxjcksn
Explorer
Mar 19, 2014
Ahh finally I get to sit down. Thanks for the input ... almost at an answer I believe :-)

I would not have thought the situation of having just 3 wires as a feed would have caused so many problems lol ! and so much variety in answers.

@enblethan - good catch on the GFCI receptacles - they are not i the shed and will upgrade them - in the RV I believe they are !

So, to surmise, my installation continues as planned. Thursday and Friday this week I will have all the wiring in and done.

Ground rods will be in - Tied to a Ground Bar inside the Box
So far I think it was agreed on BONDING the Neutral Buss to the Box as well !

So in effect the Ground and Neutral are joined at the shed.

Here's my query on this ... will this not give the current an alternative path to travel along ? and it what circumstances would this become dangerous ? especially since the ground could effectively become a pathway ?
My understanding, basic as it is though, is that the electricity should take the path of least resistance ... in this case the Neutral back to the main box - even though 200ft away, since the ground rods and wire would still provide greater resistance?

The only other option I see being - not to bond the Neutral .....
Bind the Neutral and Grounds for the Receptacles in the barn (as they were before and working as such) and ......
Still wire the TT30 properly (not binding the ground) and using the ground on the box / grounding rods for lightning and high spike protection.

Thoughts? and thanks all again for the continued input :-)
enblethen
Nomad
Mar 17, 2014
I would install as provided in the 2005 NEC article 250.32 (B) (2).
Install your ground rods, connect the ground rod to the Grounded (neutral) conductor coming from the service with a main bonding jumper.
This is some what different from my original answer. I was going by memory as 2005 made many changes to art 250.
Your standard receptacles must be GFCI or should be.
This will be the easiest and safe.
jxjcksn
Explorer
Mar 17, 2014
Hey guys, I'm just back from the site and here's some more information hopefully that will help the discussion.

1. In removing the Old Box once all wires were disconnected, I tested continuity from Neutral bar to case - there was none ! Hence the Neutral was floating. Means the box was NOT Grounded either.

2. In digging around under the old barn the feeding wires run directly into the ground, I see no conduit or metal enclosure / pathway - scary really but like I said 20+year ago installation.

3. There is no water / heat or gas in this Barn. The nearest water supply is a Permafrost in the front and I'm 90% sure that the water supply is fed by PVC piping under the ground. There is no other connection to the main house.

4. I am not intending on running a 4th wire underground 250ft

5. I am not getting this inspected as it is a temporary situation for my RV for the summer months for my family to live in whilst we sell our house and purchase another. I just need to make it safe.

I have not fully finished the work but did get a large amount done. I will wait on agreement from this discussion before finalizing installation. Just now the new box is in, 2 receptacles are wired (the ones I know are good) and the box is not yet bonded. 2 Ground rods are in wire not finished yet. I have the 30TT and cable ready and plan to finish that installation mid week. (Gravel delivery for RV coming up tomorrow) 5th load, *sigh.

Many thanks once again guys
enblethen
Nomad
Mar 17, 2014
That has all been changed. I am looking at also an older version of NEC 2005 addition. 250.32 specific covers buildings or structures supplied by feeder or branch circuits. Para (B) defines more specifics.
Again this is not the current NEC and I do not believe the OP is planning on getting a permit where it would be inspected.
The OP has not responded as to what type if any raceway the feeder circuit is in.
KD4UPL
Explorer II
Mar 16, 2014
enblethen, I refer you to 250-24(a) in the 1996 NEC. It's the only older version I have handy but judging by the OP's description of this building I suspect it's at least that old.
"When two or more building or structures are supplied from a common ac service, the grounded system in each building or structure shall have a grounding electrode as described in Part H connected to the metal enclosure of the building or structure disconnecting means and to the ac system grounded circuit conductor on the supply side of the building or structure disconnecting means."

If this were not the case then any ground fault in the second building would rely on the earth for a path back to the main service grounding electrode and thus back to the utility transformer. Not only is it unlikely that this path would conduct enough current to activate the over current protection and clear the fault it would violate 250-51

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