Advice Needed to Wire in the Generator

[ClydesdaleKevin]

Sent: 4/24/2005

Well folks,

Like I said in another thread, the Generac is all bolted in, wired to the battery, and almost hooked up to the gas (I'm short a 6" piece, and didn't realize it until the sun was almost down).

I have a question about the wiring though, and since you all run old coaches like mine, maybe you can help.

My rig is set up with a single circuit coming from the generator.  In other words, in the generator compartment is the relay box where you wire the generator in.  Coming from the box and going into the coach are only two wires, black and white.  These wires make thier way to the electrical panel under the kitchen bench, where the main breaker box is, as well as the converter/inverter and the 50' shore power cord. 

The relay box in the generator compartment has one 30 amp breaker, while there are 3 30 amp breakers under the kitchen bench, isolating the AC, and 2 other circuits.

The new Generac has TWO power wires coming out of it, as well as 2 common wires (white), and a green for ground.  The instructions show pictures of modern relay boxes, with multiple breakers and TWO circuits coming out of them:  The primary, which I have, and a secondary for a second AC unit.

One of the power wires coming from the Generac is red, and its for a 30 amp circuit.  The other is black, for a 20 amp circuit.  Red is the primary according to the directions, and black is for the secondary circuit, which I don't have.

Here is my question:  I do NOT want to rewire my whole rig, so what should I do?  I was thinking that I should tie in both commons to my common white wire, and the RED 30 amp to the Black in my circuit box.  The Green ground gets attached to the relay box, according to the directions, so that's not a problem.  The 20 amp Black wire I'm thinking of just taping off with electrical tape, and leaving it disconnected.

Any suggestions?

In summary, this is how I propose to wire it:

Generac, 2 common whites------->Ark, 1 common white.
Generac, Red 30 amp------------>Ark, 1 "hot" black.
Generac, Green Ground---------->Ark, metal relay box.
Generac, Black 20 amp---------->Ark, disconnected.

Any better ideas?

Should I tie the black and red together into the same circuit, or will this overload my system?  Do generators supply by "demand", or will the combination of 30 and 20 amps create a 50 amp circuit, which might be too much for my system?

I was an electronics technician in the Navy, but this system isn't the same as the battery bank system we use on Submarines.  This is a direct feed from generator to system, and puzzles me. 

Should I wire it the way I'm suggesting, or should I tie black and red together into the same circuit?

Thanks!

Kev and Patti Smith

[HeavyHaulTrucker]

Sent: 4/25/2005
 
Kevin, you're on the right track, except that your new genset is designed to support 50 amp service.  Use the red 30 amp as your primary, and cap off the 20 amp wire with a wire nut -- you don't need it.  Later, if you do re-wire and put in a 50 amp converter, you can then use both to supply the converter.

John

[DanD2Soon]

Sent: 4/25/2005

Kevin,

Looking at your picture of the installed Generac and a separateGenerac spec. sheet for your unit...got me to thinking about the "possibilities."

As you were thinking & John confirmed, the red, white and green wires are the ones you want to tie into the generator disconnect switch that feeds the Ark's breaker panel through wiring that was designed for 30 amp service. That "Red" circuit is overcurrent protected by a generator mounted 30 amp breaker and all of that fits in perfectly with your plans.

Possibility = The "Black" circuit is overcurrent protected by separate 20 amp breaker, also generator mounted, and could very easily be used to feed an "outside" 110 volt utility receptacle (for power tools, battery charger, etc.) that could be mounted just below your disconnect in the Ark's generator compartment.

All you'd have to do is mount that receptacle box with a short nipple from the bottom of your disconnect and feed it electrically by passing the black hot wire and one of the white neutral wires, (they are both attached to the same point inside the genset) through the disconnect and nipple to the receptacle and adding a green jumper from the ground terminal in the disconnect to the ground on the receptacle.

Just a Thought...
DanD

[ClydesdaleKevin]

Sent: 4/25/2005

Awesome idea!!!  I've got to run to the auto parts store for some fuel hose tomorrow, so I'll swing by the hardware store and pick up an outside receptacle.  What an outstanding idea!

Kev and Patti Smith

[DaveVA78Chieftain]

Sent: 4/26/2005

I don't have the wiring diagram, but I suspect the 20 amp and 30 amp circuits are 180 degrees out of phase with each other.  Measuring across them will most likely produce 220VAC.  You can use the extra recepticle idea but never tie the red and black together or you will have a 50 amp short resullting in one toasted generator.

Dave 

[ClydesdaleKevin]

Sent: 4/26/2005

Ok, she's all wired in and running great.  I traced the conduit cable to where all my coach electrical works are (under one of the kitchen benches), and it ends at a metal box, wires cut, and not attached to the primary system or the 12 volt system.

What do you all think of this idea?

Under this same bench is also my coil of shore power cord.  There is an outside hatch that the cord pulls through to plug it in.  Rather than wire the generator into the main breaker box, why not, where the conduit is cut off, add a 30 amp receptacle?  Then, when I'm not on shore power, I could plug my cord into the receptacle.  Will this work?  Seems to me like it should work fine, and would ensure that my generator is isolated from the rest of the system and can never get any back-feed.

What do y'all think?  Advantages or disadvantages?

Kev and Patti Smith

[DanD2Soon]

Sent: 4/26/2005

Kev,

That's exactly the way mine came from the factory! With a 30 amp receptacle just inside the shoreline exterior access door - When you unplugged from shore power, you just coiled the cord inside the compartment & plugged its' end into the genset receptacle. AND like you said - It's impossible to get it wrong - You're either on Generator or shore power, never both!

DanD

[Froggy1936]

Mine is the same way either shore or gen never both. Frank

[ibdilbert01]

If you want to get a bit fancy, you could always use an automatic transfer switch.   I like the Iota ITS-30R 30amp or  ITS-30R 50amp.  Its nothing more than a very large fast  mechanical relay thats fires on a 20 to 30 second delay to give the genset time to build up speed.  I've got one on my inverter, 2nd year no issues, I think Iota makes a good product.

[4winds]

Ok,I've read this thread.  My question is this:I finally got my 4KW Onan running and checked the output at my  recpt in the shore pwr compartment-reads 220VAC.  My shore pwr cord is 30Amp and won't plug in.  I'm confused any guesses?  Ed

[Froggy1936]

Im not shure but you do not want to plug your 30 amp (110 V) shore cord into a 220 V outlet  I dont think so anyway  Frank

[ibdilbert01]

I think the standard 50amp plug that you see in RV parks is 220.   They are feeding your panel both legs of the transformer, however most RVs are wired not to take advantage of the 220.   Just half of the breakers are on one leg, and half are on the other.   Also some of the Onans could be wired 220 or 110. 

[ibdilbert01]

This article was copied from a PUBLIC posting on the Open Road Forum.

There are 4 receptacle configurations that you will run into in the campgrounds. From the ANSI/NEMA specification WD 6-1997:

15 Amp - the common duplex receptacle that you have at home and the plugs on the standard extension cords, etc. These are ANSI/NEMA 5-15R and 5-15P and are rated for 125Volts/15Amps. The National Electrical code allows the duplex receptacle to be connected to a 20 Amp breaker even though each receptacle and the plug that goes into it are only rated for 15 Amps; and in your home, several duplex receptacles may be connected to the same breaker (often all the outlets in a room will go to one breaker).

20 Amp - becoming more common in the GFCI protected circuits. The receptacles look much like the 15 Amp ones, except one socket on the receptacle looks like a T laid on its side. These are ANSI/NEMA 5-20R. The 20 Amp plug is an ANSI/NEMA 5-20P and looks much like the common 15 Amp plug, but has one blade rotated 90 degrees. These are rated for 125Volts/20Amps. The 15 Amp and the 20 Amp plugs will plug into the receptacle. Again, these can be connected to a 20 Amp breaker.

30 Amp - obviously designed for RV's. This is the common 30 amp RV connector with one half round pin and two large blades that are angled. The receptacle is an ANSI/NEMA TT-30R, and the plug is an ANSI/NEMA TT-30P. These are rated for 120Volts/30Amps (note that the NEMA rating is not 125 Volts on this configuration - interesting). The TT is for Travel Trailer as it is listed that way in the "Description" column in the NEMA table - I guess that's because there were a lot more travel trailers than motorhomes when this plug was put into use. I have seen these labeled "RV" instead of "TT" in catalogs and on the store shelves. These can be connected to a 30 Amp breaker.

50 Amp - the common four pin configuration used for larger RV's. The receptacles are ANSI/NEMA 14-50R and the plugs are ANSI/NEMA 14-50P. The half round pin is ground, the blade directly across from it is Neutral, and the other two blades each have 120 Volts. If wired per the National Electrical Code, the two 120 Volt feeds are of opposite phases so that you get 240 Volts when you read across them and 120 Volts between each of them and neutral or ground. Each of the two power sockets can be wired to a 50 Amp breaker - for 240Volts, the two breakers are "ganged" (the handles are connected together) or are of a special design with only a single handle. However, some campgrounds may only have 30 or 40 Amp breakers on the power feeds to these receptacles.

A disclaimer: the National Electrical Code is from the National Fire Protection Association and is not a law. However, almost all community building codes incorporate it into their code. Many amend it in some way. So not every campground - or RV - in the country is wired to the NEC. What follows is based on the NEC, and what I have found in almost every campground I've been in.

New electrical installations will have the 15 or 20 and 30 Amp receptacles with GFCI - either built into the outlet or in the breaker. The 50 Amp receptacle will not have GFCI (but I don't doubt that it's in the future). The requirement for GFCI on outdoor outlets became part of the National Electric Code in the early 70's. So any campgrounds that were built after that time, or had the electrical system upgraded, should have GFCI on the 15 Amp receptacles. The requirement for the 30 Amp outlets to be on GFCI is more recent, but I don't know when it started.

Some comments about items in this thread and some knowledge I've gained from this forum:

If the "cheater" will work, you can bet that the campground wiring is pretty old or not done to the National Electric Code.

From my own experience, and from statements in other threads, you can expect to find outlets incorrectly wired or with a wire not connected sometime in your camping experience. You may also find incorrect receptacles. I've seen receptacles that look a lot like the 30 Amp RV receptacle installed, but one or more of the sockets are not correct and the RV plug won't go in.

From another thread a couple of months ago, it became apparent that many RV's with the 50 Amp plug and cord have a power panel that does not allow for a 240 Volt circuit to be connected - it has two 120 Volt circuits available to the breakers in the panel, but no way to connect a "ganged" breaker or a 240 Volt application. (A forum member had to have an additional panel wired in so he could put in a 240 Volt dryer.) I suspect there are a number of variations on the power panels and main breakers that come in the wide array of RV's that have been manufactured over the years.

If you have a 50 Amp cable on your RV, you should be checking the receptacle before you plug in with a circuit tester or voltmeter. (Or install a power monitor system in your RV that will do it for you.) If the neutral wire is not connected to the receptacle and you plug in, something in your RV will probably "smoke" as, without going into the electrical details, it'll have about 240 Volts applied. Other forum members have been victims; I've seen 3 or 4 50 Amp outlets where the neutral wire had come loose and was not making contact and I am sure that a previous RV'er left with a problem. It is also wise to throw the breaker in the campground panel before you plug in. That way you can't get the hot pins connected before the neutral is connected, and it don't take long for electricity to do it's damage.

Outlet testing. You can buy an outlet tester that has lights to indicate that the outlet wiring is normal or has problems for less that $5 at a hardware or building supply store. (Or you can buy a voltmeter and learn use it if you don't already know.) You can also buy much more expensive circuit testing devices that do the testing and measure the voltage and/or frequency. But all of them I've seen plug into the standard 15 Amp receptacle. So add a 30 Amp male to 15 Amp female adapter available at RV stores for less than $5 and you can plug the circuit tester into the adapter, and the adapter into the 30 Amp receptacle and check the 30 Amp receptacle. Add the 50 Amp male to 30 Amp female adapter, available at RV stores for $15 to $20, plug the 30 Amp adapter into it, the tester into the 30 Amp adapter and you can test 3 of the 4 wires in the 50 Amp receptacle - ground, neutral and one of the two power leads. Neutral is the critical one for an RV connecting to a 50 Amp receptacle. If the second power lead has no power, some thing(s) in the RV - like one air conditioner - won't work; but if neutral is missing, some thing(s) in the RV will probably need to be repaired or replaced.

GFCI - My simple explanation. The GFCI circuit has electronics in it that measures and compares the currents in the hot and neutral leads. If they are not equal, the circuit trips and removes power. That usually occurs when some power flowing through either the hot or neutral lead finds a path to ground. The tripping action is almost instantaneous and occurs with an extremely small amount of power difference - a few thousandths of an amp.

[4winds]

I agree with the above but my old girl has stanndard 30 Amp shore cord and everything works,however my Onan recept is a 220VAC 50Amp .  Have never wired or rewired a gen set so what do I do?

[ibdilbert01]

If you didn't want to rewire the genset with a new plug, I suppose you could use an adapter. 

http://www.google.com/search?hl=en&safe=off&client=firefox-a&hs=yZk&rls=org.mozilla%3Aen-US%3Aoffical&q=30+amp+to+50+amp+adapter&aq=f&aqi=&aql=&oq=&gs_rfai=

[4winds]

So all I need is a 50 to 30 adapter,right?  Thanks,I was an aircraft electrician but this gets confusing.  Ed

[ibdilbert01]

Maybe something like this?

http://images.campingworld.com/is/image/cwi/40000/48858nNew.jpg

[4winds]

Yes,thanks a bunch.  Really had me bumfuzzled.  Ed

[JDxeper]

I believe there is another one which just plugs into the adapter,  Wal Mart or Camp World 30-50 amp adapter.  Similar to the 30amp to 15 amp adapter.
JD

[DaveVA78Chieftain]

When you say you have a 4KW Onan generator, are you reffering to the older 4.0CCK-3CR type generator?  If so, then be aware that when this model of generator is wired for 240VAC operation, you can only pull a maximum of 16.7 amps from each side.   In order to use the full 33.4 amp capability you have to wire the generator for 120VAC operation.  The adaptor that was recommended above only uses half power (16.7 amps).   Reference Onan Techinical bulletin TI-012, Table 1.

Dave

[ibdilbert01]

Dave is very correct.  The adaptor above works by only using one leg of the 220 on the genset, the other leg simply is not used.   Normally this wouldn't be too big of an issue, however you usually don't see 50 amp plugs on 4k gensets.

[4winds]

oops,backk to the drawing board.  It is original to my '81 Executive so I'll have to find out how to rewire for 30Amp.  Ed

[RV Mech Tech]

Can anyone answer  a question for me- why does the electrical code in the USA allow for a 20 amp breaker on a 15 amp circuit ? - this amperage rating exceeds the 15 amp conductors (wiring, outlets etc. and 'ampacity rating' )  ability for overcurrent protection- if an electrician in Canada were to install a 20 amp breaker ( rated for 12/2 wiring) on a 15 amp (rated for 14/2 wiring)  he would loose his electricians license -  in the past we have had several new RV's with 15 amp 14/2 wiring for microwave ovens for regular microwaves requiring 15 amps and we have seen and had to change these circuits for convection oven microwaves that required 20 amp circuits  so that the RV would be certified for sale in Canada- having an RV CSA certified for sale in Canada adds to the price tag for an RV that is sold in Canada -  my concern here is that anyone that is wiring their Classic  Winnebago or RV may be inviting trouble if following these rules - any comment would be appreciated - thanks.    Hm?

[DaveVA78Chieftain]

Ed,
So you do have a Onan 4.0CCK-3CR type generator?  I can post some information if you do.
the 3CR breaks down too:
3C - Single phase 3 wire connection that is changeable
R - A remote starter panel is supported
You need to get a better idea of your total electrical system before making changes.  Is there some sort of dual distribution network.

As far as I can see, this type of generator did not come with a recepticle built in.  Just wires that you or the installer connected to a recepticle of choice.  There are 4 wires involved.   I will post the information when I get home.

Dave

[ibdilbert01]

Yeah, the codes here can be a bit tricky to learn and actually prove to be a bit overkill in some situations.

Code says a breaker can not exceed 15 amps on a 14/2 wire, and cannot exceed  20 amps on a 12/2 wire.     The reason is if there is a direct short, the wire can't melt and catch things on fire before the breaker trips.     

Most contractors these days just use 12/2. 

Also our 20 amp outlets are very rare, but are shaped a bit different so you can't plug them into a 15 amp outlet, but you can plug a 15 amp plug into a 20 amp outlet.   

Almost all appliances sold here including microwaves are designed 15 amps or under, so a standard plug can be used.

So if Canada has a lot of 20 amp appliances, I can see where your fustration is coming from.