110 Electrical Guru needed

[bobofthenorth]

The picture is of my transfer switch.  One of the joys of owning a bus that somebody else converted is that you get to play Sherlock Holmes fairly often.  Today the topic is: "How does my transfer switch work?"  The first step in answering that question for me anyway is to figure out what I have.  Can somebody please identify this beast?  I can't see a name on it and it is in an aluminum housing that Bruce Coach obviously fabricated with a BC certification sticker stuck on the outside of it and no other markings.



My goal is to delay the switch-over from inverter to generator in some easy fashion.  My Kubota rebuilder went on ad nauseum about how I shouldn't start the Kubota and immediately put it to work.  He's probably right and it seems to me that there is likely some simple way to accomplish that with the existing x-fer switch but first I need to figure out what I have. 

[Sean]

Bob,

I can't identify make or model from what you've shown.  Many switches look just like this one.

I can tell, you, however, that I see several problems with it right off the bat.

Chief among those is the fact that the neutrals are all tied together.  Assuming there is a ground-to-neutral bond in the generator, this will give you a multiply-bonded system whenever you connect to shore power, a potential hazard.

There are also several color-code problems, at least one bare wire that should not be, and some shoddy workmanship in general.

The little circuit board on the top of the picture controls when the switch transfers from shore (which appears to be default here) to genny.  It does not look to be of an adjustable-delay type, but you can add a simple delay timer in the sense lead running from the black genny terminal to the circuit board.

If it were my coach, I would replace the switch with one that switches all three current-carrying conductors and has an adjustable delay timer built in.

Give me a call if you want to discuss in further detail.  My phone number is on the "Who We Are" page linked off the blog (in the sidebar on the right).  Not posting it here so it does not get harvested by bbs-crawlers.

-Sean
http://ourodyssey.blogspot.com

[bobofthenorth]

Sean I just checked this with a DVM and you are correct that the genset has the neutrals bonded all the time. You are right -- a 3 conductor xfer switch would alleviate this problem. The neutral bus and the ground bus are completely separate in this panel.  Any reccs for a mfr of a 3 pole switch?  Preferably one that will be available on the eh side of the 49th parallel.

As far as the delay after the genset starts you have already told me enough to accomplish what I need to.  I'm going to put a simple toggle switch in what you called the "sense lead" so that I can control when the circuit board sees power from the genset.  

FWIW the colour code issues you refer to are actually dealt with through tape wrapping.  There could likely be more tape wrapping but there is enough that it is clear what the wires are when you can see the panel.  I gather there is some code issue with the bare wires?  

[Sean]

...  Any reccs for a mfr of a 3 pole switch?  Preferably one that will be available on the eh side of the 49th parallel.

The canonical "standard" for the RV universe seems to be the IOTA:
http://www.iotaengineering.com/its50r.htm

This unit is available from many retailers on-line and brick-and-mortar, and is listed in both US and Canada.  About $160 or so.  Personally, however, I don't favor it, because of the way the switching is implemented internally.  I favor the model 501 from Parallax Power:
http://www.parallaxpower.com/ATS.htm

I found this predecessor to the 501 on-line, looks like they will ship up north:
http://www.dan-marc.com/1-ats5070.html

And this looks like it would work fine and be shipped to you as well:
http://www.rvpartscenter.com/ProductDetail.asp?ProductID=20497&StoreID=14&DepartmentID=65&CategoryID

All of the above switch both hots and the neutral, and have built-in generator delay timers.

FWIW the colour code issues you refer to are actually dealt with through tape wrapping.  There could likely be more tape wrapping but there is enough that it is clear what the wires are when you can see the panel.

Well, I have to confess that I don't really know what the code says on, how did you put it, the "eh" side of the 49th.  But down here, tape wrapping is never allowed on a ground wire -- that needs to be either bare copper or green, with optional yellow stripe, for its entire length.  You can't simply put green tape on the end of a red wire.

Also, all conductors must be properly identified and the method of identification needs to be clear.  On your installation, the input conductors from the shore and genny appear properly identified, but after the relay, both hots are red all the way out -- no way to tell the two hots apart.

Looks to me like they got a fire-sale on red wire.  I have to say, if this is the level of work coming out of Salmon Arm, my opinion of Bruce has dropped a few notches.

I gather there is some code issue with the bare wires?  

The bare ground wires are fine.  I thought I saw a bit of bare wire on one of the hots coming from the genny, but that could just be the way the photo came across.

Also, FYI, some of the wires look to be too small for the application.  Notably, the genny lead-in, although I don't know what size unit you have.

HTH,

-Sean
http://ourodyssey.blogspot.com

[bobofthenorth]

All of the above switch both hots and the neutral, and have built-in generator delay timers.

Thank you sir - we will be in Calgary next week where I expect I will be able to find what I need now that I have a half-assed idea what that is.

Looks to me like they got a fire-sale on red wire.  I have to say, if this is the level of work coming out of Salmon Arm, my opinion of Bruce has dropped a few notches.

Be gentle with Bruce.  This coach is serial number 1 or damn close to it.  More importantly the P.O. (AKA Doofus) had some kind of dust up with Bruce toward the end of the project and ended up taking the coach home to "finish" himself.  Any time there is an electrical issue I can usually trace it to Doofus's work although I believe that this panel was part of Bruce's work. And FWIW the panel does have a BC electrical inspection sticker on it which means that somebody with a clipboard and a blue suburban was at least close enough to it to put the sticker on.

Also, FYI, some of the wires look to be too small for the application.  Notably, the genny lead-in, although I don't know what size unit you have.

You are right, they do look marginal.  I will check that out against my favorite online gauge calculator because I am virtually certain that doofus installed the gennie.  It is a 6500 watt 240 volt unit FWIW.

[bevans6]

What is the color code standard for wiring in an RV?  I would think that the standard house AC wiring color codes would be followed for RV wiring - bare/green ground, white neutral, black hot, red alt. hot.  The only tape wrapping that I am aware of being allowed is to wrap white for black when you are using /2 romex to wire a two station light switch.  But what is the standard for DC wiring?  I confess I like to use red for hot and black for ground, but that raises the issue of confusing 12vdc black gnd for 120vac black hot, which i don't like at all.  I'm just getting ready to redo all of my DC wiring.

I just ordered  an IOTA transfer switch for the power upgrade I am doing on my bus.  I'm setting everything up for 30 amp 120vac service.  My gas generator has switches to disable power output while starting.  It is a 6600 watt gennie, with two 30 amp output sections, so I will run the bus off one side (the 120/240 side) and save the other side for off-bus uses.

Brian

[bobofthenorth]

There is a CSA standard for RVs. Here is one source.  I expect you can get it directly from CSA as well but I didn't take the time to look.

There is also a Canadian Electrical Code (CEC) which is similar but not identical to NEC.

[Len Silva]

I agree with Sean on the difference between the Iota type transfer and the Parallax type.  The former uses two DPDT contactors, one for the power leads and one for the neutral.  It is possible for one to fail leaving the neutral untransferred.
The other type (Todd Engineering/Lyght Power Systems/ESCO) use two three pole single throw mechanically interlocked contactors.  These are inherently fail safe. They require either shore power or generator power to operate. Without either source, there is no connection at all.

The latter are actually made from a three phase motor reversing contactor with an auxiliary contact and time delay circuit. Those knowledgeable in motor controllers could probably fabricate their own at considerable savings. They are more expensive that the Iota type but safer and more robust in my opinion.

[bobofthenorth]

The latter are actually made from a three phase motor reversing contactor with an auxiliary contact and time delay circuit. Those knowledgeable in motor controllers could probably fabricate their own at considerable savings. They are more expensive that the Iota type but safer and more robust in my opinion.

Keep going with that thought please.  I'm happy with the control circuitry, all I'd like to do is swap out the current 2 pole contactor for a 3 pole contactor. 

[Sean]

Be gentle with Bruce.  This coach is serial number 1 or damn close to it.

Oh, OK.

You are right, they do look marginal.  I will check that out against my favorite online gauge calculator because I am virtually certain that doofus installed the gennie.  It is a 6500 watt 240 volt unit FWIW.

OK.  A 6,500 watt genny will produce a tad less than 30 amps at 240 volts -- I would wire that with #10.  All the 50-amp stuff should be wired with #6.  Hard to tell from the photo what gauges you actually have in there.

What is the color code standard for wiring in an RV?  I would think that the standard house AC wiring color codes would be followed for RV wiring - bare/green ground, white neutral, black hot, red alt. hot.  The only tape wrapping that I am aware of being allowed is to wrap white for black when you are using /2 romex to wire a two station light switch.

The identification standards for 120/240VAC wiring are the same in RVs as in other types of uses.  The code does allow for field identification of conductors using a durable marking system such as colored tape at the ends.  The identification must be done at each panel, fixture, junction, splice, etc. and it must be consistent.  Ground wires are not permitted to be identified in this manner (until you get into very large gauges), they must be bare, green, or green with yellow stripe for the full length.

But what is the standard for DC wiring?  I confess I like to use red for hot and black for ground, but that raises the issue of confusing 12vdc black gnd for 120vac black hot, which i don't like at all.

There is no code standard for wiring below 30 volts.  I recommend you follow whatever system your coach manufacturer used to identify hot an ground.  There should be no opportunity for confusion with the AC wires because those are required to be separately enclosed.

...  I'm setting everything up for 30 amp 120vac service.  ... I will run the bus off one side (the 120/240 side) and save the other side for off-bus uses.

I'm not sure I follow this -- why set the coach up for 120 only if you have a 240 genny?  Also note that if you have more than five circuits or two thermostatically controlled appliances (e.g. an air conditioner and a water heater), you are required to install a 50-amp, 240-volt system.

I agree with Sean on the difference between the Iota type transfer and the Parallax type.  The former uses two DPDT contactors, one for the power leads and one for the neutral.  It is possible for one to fail leaving the neutral untransferred.
The other type (Todd Engineering/Lyght Power Systems/ESCO) use two three pole single throw mechanically interlocked contactors.  These are inherently fail safe. They require either shore power or generator power to operate. Without either source, there is no connection at all.

Yes, this is precisely what I meant when I said I did not care for how they were wired internally.  I was just trying to keep the discussion simple...

The latter are actually made from a three phase motor reversing contactor with an auxiliary contact and time delay circuit. Those knowledgeable in motor controllers could probably fabricate their own at considerable savings. They are more expensive that the Iota type but safer and more robust in my opinion.

If you go to the electrical section on my web site, you will see that we did exactly this (http://ourodyssey.us/bus-e-ats.html).  I used a Telemecanique reversing motor starter as the core, and added other components to achieve the delay and some other things I was trying to do.  Also, my genny puts out 70 amps, so the 50-amp factory units were not big enough for us.

Keep going with that thought please.  I'm happy with the control circuitry, all I'd like to do is swap out the current 2 pole contactor for a 3 pole contactor.  

Bob, I found my contactor on eBay for perhaps $50 (the size I used probably runs ten times that much at retail).  What you are looking for is a "three phase reversing motor starter" rated for 50 amps (although contactor ratings are somewhat bewildering).  You can buy them retail from places like Grainger, but they are pricey.  If you find one, I can help you get it hooked up.  The IEC type is generally smaller for a given rating than the NEMA type, which may be a factor if you intend to use the existing enclosure -- I used an IEC model.  You want a NEMA size 3, or an IEC model with a rating of 50 amps "AC-1."

This is what you will find inside the units I suggested, with the added advantage that there will also be the delay timer circuitry included, something you will need to add if you just swap contactors.  Delay timers are also fairly spendy.  These can be had from Grainger, Allied, Newark, etc..

-Sean
http://ourodyssey.blogspot.com

[Len Silva]

Sean,

The breadth of your knowledge is impressive.  Your interest and research into the proper method of accomplishing a project, whatever it may be, is a value I share.

Your communication skills and attention to detail however, are in a different league from most of us mortals

Thank you so much for sharing, you are appreciated.

Len

[Sean]

Thanks, Len.  Always good to feel appreciated, especially after taking so much flak for being the safety Nazi.

-Sean
http://ourodyssey.blogspot.com

[Len Silva]

For the time delay, you could probably use an air conditioner compressor delay unit, some can be adjusted from 10 sec to 10 minutes and run $30-$50.  Nick might be able to help on that front.

[poppi]

Sean,

    I'm surprised you made reference to a political party 

   I'd be more afraid of a self reference to SS though.

   Are you taking any pictures if how the leaks are being fixed on your bus?

   Just interested on the hows and maybe you'll start a thread on it.

Skip

[bobofthenorth]

The circuitry I have already has a delay built in.  I have never timed it but its likely 15 or 20 seconds.  Long enough that I can walk around the bus and hear the transfer switch click in.  My intent is to manually delay the existing delay so that I can control the warm up time for the Kubota.

And ............. what Len said.