Electric Rig Wiring help needed.. any E.E.'s out there?

[Brewineer]

Howdy,
I've made numerous assumptions with this, but here is a rough wiring diagram. I'll let the other posters peer review and point out errors:
http://img511.imageshack.us/img511/705/brewrig.png

 

[lazybean]

if the elements are cord n' plug connected, why not use the DPST SSR the right way, Connect it to a single receptacle and just plug in the Element you want to use?

 

[passedpawn]

if the elements are cord n' plug connected, why not use the DPST SSR the right way, Connect it to a single receptacle and just plug in the Element you want to use?

If you are talking to me, you are right I could do that. I would have to switch the thermistor, too. Just thought this would be a bit easier.

 

[lazybean]

Howdy,
I've made numerous assumptions with this, but here is a rough wiring diagram. I'll let the other posters peer review and point out errors:
http://img511.imageshack.us/img511/705/brewrig.png

Looks good to me, just need to add the fusses

 

[cyberbackpacker]

Howdy,
I've made numerous assumptions with this, but here is a rough wiring diagram. I'll let the other posters peer review and point out errors:
http://img511.imageshack.us/img511/705/brewrig.png

Wow great first post Brewineer! Thanks so much... I have to head back to work in a few minutes, but look forward to studying this more in depth tonight!

I do appreciate you taking the time to do this!

 

[Plan9]

That drawing is very good.
It also saves me the time of doing one.

 

[cyberbackpacker]

So, i studied the diagram that Brewineer submitted, and I broke it down to a single element drawing so I could see if I am understanding everything.

Additionally, I swapped out the two single ssr's for a dual ssr; I also added inline fuses where I think they should be installed.

Can you guys look this over and let me know if I am on the right track?

Thanks again guys!

http://farm3.static.flickr.com/2510/4055318309_6bcae1e24a_o.png

 

[lazybean]

you dont need 4 fusses, fuse each leg (2 total) then branch off the load side of the fuses to the SSR and the switch.

 

[lazybean]

................--------------------
--{fuse}--[.............................]--(HOA switch)-----Heater
................-----(SSR)----------


So hard to draw with text.

 

[cyberbackpacker]

Ok, so fuse each hot leg from the distribution block, and then after the fuse, branch again and send one branch to the SSR and the other to the DPDT?

 

[eccsynd]

Looks good to me cyberbackpacker. Great work. Now get this thing wired so we can start talking process control!

 

[Brewineer]

yeah, you have the right idea with the fuses.

Good call with fuses, lazybean, we really don't want this to burn down.

Keep in mind you shouldn't run a ground wire from the BCS-460 to your ground distribution block, as the bsc-460 'ground' is actually the neutral. You don't want to inadvertently bond you ground and neutral lines with your BCS-460.

 

[Plan9]

Keep in mind you shouldn't run a ground wire from the BCS-460 to your ground distribution block, as the bsc-460 'ground' is actually the neutral. You don't want to inadvertently bond you ground and neutral lines with your BCS-460.

BCS should really call that a "COMMON"

 

[cyberbackpacker]

Keep in mind you shouldn't run a ground wire from the BCS-460 to your ground distribution block, as the bsc-460 'ground' is actually the neutral. You don't want to inadvertently bond you ground and neutral lines with your BCS-460.

Thanks for mentioning that!

 

[JKoravos]

I have talked about this before, Switching one leg of 240v leaves the entire circuit energized the entire time(even if the circuit is open, it is still energized). This is a huge Code violation, NEC and UL.
Also, because you are using multiple receptacles, elements and current ratings, you are going to have to use fusses to protect all the different ratings.

I just had a friend look up the UL code for heaters, and unless they have integrated Thermal protection they will each need their own set of fuses.

I'm sure there will be the usual flurry of Anti-code replies. but it still doesn't change the fact its wrong and unsafe.

Yes, the entire circuit is energized if you only kill one leg, but there isn't anything inherently unsafe about that.

 

[eccsynd]

Keep in mind you shouldn't run a ground wire from the BCS-460 to your ground distribution block, as the bsc-460 'ground' is actually the neutral. You don't want to inadvertently bond you ground and neutral lines with your BCS-460.

Not bad advice, but not necessarily for that reason. The BCS GND pin is a DC GND. If you connect the DC GND to earth ground, you're just forcing it to be a common reference point.

The BCS GND is not connected to the 'neutral' line. The 2 prongs of the 'wall wart' that power the BCS are attached to the primary coil of a transformer, and the secondary coil is fed through a rectifier/regulator to create DC voltage. This is all inside the 'wall wart'. In fact, transformers are used in this way to isolate AC circuits.

So should the BCS GND pin be connected to earth ground? Doesn't really matter. Personally, I don't because it doesn't need to be, and it may slightly increase the risk of noise into the DC circuits. Although I've never witnessed it causing ill effects.

 

[CodeRage]

The only reason you may want to bond the BCS to earth ground is to ground the chassis if it is made of metal, especially if you have 110v feeding into the thing on some dry contacts. From what I've glanced over it seems to be low DC voltage which isn't anything to really worry about.

What bothers me is this DPDT switch I keep seeing. For a 50 amp service you are looking at contactors, not relays or switches. Auber sells em cheap but they are only rated up to 40 amps. Thats what I used for mine and I dropped my service through 30Amp breakers for each element. Contactors usually only come with normally open contacts for the high current stuff. So it may take two contactors and a three position maintained panel switch to drive the DPDT-ish functionality.

Why bother with the fuses? Breakers are meant to protect wire from burning up, fuses are meant to protect devices. Being a big resistor there really isnt much to protect on an element. If it leaks to ground you breaker is going to pop, which should be rated less than the current rating of the wire. Either one isnt going to save your butt should you get hooked up to it. You'll be long dead before that fuse pops, should you become the dead short.

Ground the crap out of the chassis and everything metal in the system. Use the right size breakers and wire, GFCI is good extra protection.

U/L isn't really a mandated requirement to build anything to, unless you plan to sell these things and want to be able to insure yourself against any damages this thing may cause.

 

[Brewineer]

Not bad advice, but not necessarily for that reason.
The BCS GND is not connected to the 'neutral' line. The 2 prongs of the 'wall wart' that power the BCS are attached to the primary coil of a transformer, and the secondary coil is fed through a rectifier/regulator to create DC voltage. This is all inside the 'wall wart'. In fact, transformers are used in this way to isolate AC circuits.

You are correct; I'm not sure what I was thinking and feel pretty dumb now. Maybe I'm just stressed out/weary from work and can't think as well on my off time. It suffices to say that this project is much more interesting than anything I do at work.

What are the ratings of the DPDT switch being used?

 

[cyberbackpacker]

The DPDT for the elements is rated for 30amps

 

[BrewBeemer]

Be careful on picking a switch, contactor or relay as inductive load ratings are different than resitive loads when switching or controlling your brewing system. By this the size of the contacts and their maximum rating like SSR's or SSRD's if your thinking properly the 75% maximum rule allows for a longer electronic component equipment life.

 

[CodeRage]

Be careful on picking a switch, contactor or relay as inductive load ratings are different than resitive loads when switching or controlling your brewing system. By this the size of the contacts and their maximum rating like SSR's or SSRD's if your thinking properly the 75% maximum rule allows for a longer electronic component equipment life.

Inductive load ratings have more to do with the gap between contacts and not the actual current rating. When the contactor is opened it allows the field in an inductive load to collapse with no load. So the voltage spikes, commonly called an inductive kick. If the contacts are too close together it will arc across and over time will destroy them.
So it is perfectly okay to go by the inductive load rating for a resistive load.
Inductive demons tend to show their heads when you use a resistive load rating for inductive devices.

The 75% load rule never hurts .

 

[ScubaSteve]

Subscribed. This thread has a goldmine of information, thanks to everyone for their input!