Plastic electrical boxs

[thisguy]

Okay real quick, I have a plastic electrical box, fits my controller just fine. However I am unsure about how to ground it? How does one go about doing so?

[FtW]

If using an SSR for the controller there are spots for ground on the SSR.

Edit: the lower point in between the hot leads on the controller are for ground.

[thisguy]

It's this one http://www.ebay.com/itm/10000W-220v-Adj ... 2c7271bb5a" onclick="window.open(this.href);return false;" rel="nofollow

[thisguy]

Could I just ground it to the heat sink?

[FtW]

That should work, although the pot looks pre wired to the board, since the voltage pass through only requires one of the hot wires from 220V & there are 4 terminals I would think there should be a spot for ground.

Nothing for instructions with it? If you have a multimeter you could check if any of those 4 terminals has continuity with common ground (the heatsink should be grounded to the board for a test point).

[bearriver]

Two hots in, two hots out = 4 terminals. That's how it is wired.

If you want, find a piece of metal such as the heatsink and tap it for a ground screw. I wouldn't worry about it.

I just put a ground bus bar in my plastic box, but my scr's also have a grounded enclosure.

[thisguy]

No there was no documentstion. I'm guessing that it gets grounded to the heat sink cause it has little screw holes drilled onto the top slots of the heatsink.

[Danespirit]

I have the "little brother" to your model, on mine there is a extra connector on the housing of the potmeter. Ain't that so on yours?
If it's constructed like mine, which i think, the heatsink is not electricaly connected to the board.
It's just two pins soldered in the board to mount the HS.. it connects to the back of the thyristor of course.

[thisguy]

That's what it had on it as far as ground related things go.

I think I might go with the heat sink

[thisguy]

Looks like the heatsink is held in with two screws. However the heatsink has a chip directly attached to it and that chip is soldered to the board.

Maybe I won't go with that. There is that extra pin on the pot tho...if I run both grounds into a single connector and connect it to the pin, would that work?

[Danespirit]

That's exatly how mine looks too.
The tiny holes on the coolingprofile..there is a exact match at the bottom, were two pins are soldered to the print, but they do not electrically connect to the print.
The "chip" as you call it is a thyristor and connects to the profile via heatsinkcompound.
Now i don't run ground here. I have only grounded my still boiler (to the waterpiping).
Hmm..being no electrician i don't know if it would be recommendable to connect both, so i must leave that answer open.

[thisguy]

So I should ground it to the extra pin on the pot? And I ground it to my boiler as well

[Drunk-N-Smurf]

Lemmon see a pic of the bottom of the board please.

[still_stirrin]

So I should ground it to the extra pin on the pot? And I ground it to my boiler as well

What I'd do is let the motor speed controller "float". Use your hot & neutral in and out connections on the controller, as you can.

And the "extra pin" on the pot is most probably the other side of the wiper. It is electrically connected to the circuit. It is NOT the place to connect a ground buss.

Then put a separate screw in your controller box to connect the power-in ground (the copper or green wire if in the USA). Then also put the ground wire that you run to your heater element/boiler on that same screw. Since your case is plastic, those grounds will allow the motor speed controller to float around the neutral (white wire), and it (the ground stud) won't short between nay of the mounting fasteners you use to affix the speed controller.

Without knowing the specifics of your Triac, I wouldn't use the heat sink as a ground buss. Some Triacs are NOT isolated on the heat sink. Since you don't have any datasheet on the controller, I would recommend avoiding to complicate that circuit.

The circuit should work perfectly fine "floating".
ss

[shadylane]

As pointed out, there's a possibility the heat-sink is electrically hot.
If it is, and you ground it. All the smoke will leak out of the triac.

[Drunk-N-Smurf]

Look at the bottom of the board. Most properly built circuit boards have a ground circuit. The circuit will usually include at least one of the mounting holes if there isn't a dedicated ground point on the board, identifiable by tinning, or copper around the screw hole(s)

The intent is to mount the board using a standoff stud to a metal enclosure, but you could do the same thing In a plastic case. Mount the board itself using standoff studs to a conductive square of metal. Then use the same square as your grounding point for the rest of your wiring.

I don't know if I explained it well enough. If not let me know and I can take some pics of what I mean. But I would definately make sure the board is grounded. If you have AC voltage going to it, you definately want it grounded for safety.

[S-Cackalacky]

Looks exactly like mine. I replaced the heat sink with a computer CPU heat sink. The four terminals (2 in and 2 out) - one in and one out is for the controlled side and the other in/out are just connected to each other (straight through). If you look at the back of the circuit board, you'll see a line of solder running from input to output. I connected my grounds to the heat sink - one from the service panel and the other out to the boiler.

[thisguy]

There's a pic of the bottom of the board.

Im doing 120v right now, so all i have is black, white and green

[thisguy]

So I should ground it to the extra pin on the pot? And I ground it to my boiler as well

What I'd do is let the motor speed controller "float". Use your hot & neutral in and out connections on the controller, as you can.

And the "extra pin" on the pot is most probably the other side of the wiper. It is electrically connected to the circuit. It is NOT the place to connect a ground buss.

Then put a separate screw in your controller box to connect the power-in ground (the copper or green wire if in the USA). Then also put the ground wire that you run to your heater element/boiler on that same screw. Since your case is plastic, those grounds will allow the motor speed controller to float around the neutral (white wire), and it (the ground stud) won't short between nay of the mounting fasteners you use to affix the speed controller.

Without knowing the specifics of your Triac, I wouldn't use the heat sink as a ground buss. Some Triacs are NOT isolated on the heat sink. Since you don't have any datasheet on the controller, I would recommend avoiding to complicate that circuit.

The circuit should work perfectly fine "floating".
ss

Ahhhhhh, thats what I had originally when i first set it up. Then I got thinking the current might melt the plastic, so I figured id ask you guys.

So the way Im going to set it up is as such:
Black/White In from wall to controller
Green in from wall to ground screw
Black/White to boiler from controller
Ground to boiler to ground screw

EDIT: Then grounded to the boiler

[Drunk-N-Smurf]

Wow, that is some ugly ass soldering on that board lol.

Not clear enough for me to see the pathways. Was hoping to see a little better.

[thisguy]

Yah, I think it just goes from connection to connection, if that makes sense...I dont think the heatsink is connected electrically to the board...

If i can just put a screw into the box and connect the grounds without any problems thats what im going to do.

[Drunk-N-Smurf]

Yah, I think it just goes from connection to connection, if that makes sense...I dont think the heatsink is connected electrically to the board...

If i can just put a screw into the box and connect the grounds without any problems thats what im going to do.

Thing is, anytime you have ac voltage it should be bonded/grounded, just having a screw in the box that the board doesn't connect to, leaves the components open to short somewhere and potentially energize something you might come into contact with like the the knob of your pot. If the board can be grounded, then at least it can fail and stop working without using your fingers as a ground.

Just passing the ground through the box will work, but it leaves the board ungrounded.

[S-Cackalacky]

Also, if you're planning to enclose the heat sink in the box, you'll need a fan and some vent holes in the box. If you plan to run it on 120V service, there are 120V fans available, so you could run both off the same circuit. Or, you could rob a 12V fan from a computer and use a wall wart to power it.

[thisguy]

I have a fan that is going to be attached and I am going to be drilling holes in the back of the box.

I think im understanding it better now...so since the box is not directly connected to the circuit it wont have anywhere to return the electricity to...??? With that being said im guessing the ground on the boiler wont be enough?

maybe ill have to get a metal box...

what if i solder the ground into that big blob of solder on the bottom?

[Drunk-N-Smurf]

I think im understanding it better now...so since the box is not directly connected to the circuit it wont have anywhere to return the electricity to...??? With that being said im guessing the ground on the boiler wont be enough?


what if i solder the ground into that big blob of solder on the bottom?

Which blob of solder? The "big" ones I see are part of your Line voltage circuit, which you wouldn't want to attach a ground wire to.

Your circuit will be fine, it will work. But there is no fault protection. If your element fries, your keg is grounded so it will trip your breaker instead of energizing your keg. But with no path to ground on your controller board, if something fries, it could energize the stem of your knob, potentially giving you a hell of a jolt when you try to use it.

For an easy fix, you COULD solder a wire to the metal backing of the potentiometer, and run it to the ground screw you put in your box. At least that would protect the pot from being energized. The pot bodies are USUALLY soldered into the ground circuit of the board, so it should theoretically protect the rest in the event of a fault as well.

If I could see the backside clearly I'd be able to trace the paths and say for sure if the ground circuit is complete.

[thisguy]

So your saying put the grounds on the ground screw and run a wire to the metal backing of the pot to the ground screw? What if I used that extra connector that is attached to the pot instead of the ground screw?

[Drunk-N-Smurf]

Is that extra connector part of the back of the pot? Or is it going somewhere else? (It looked like part of the back in the pics, but I thought someone had said it wasn't.)

If it is just part of the back, then there's your ground. Solder/attach a wire to that and run it to your ground screw, run your keg ground and feed ground to the same screw, and you'll be good to go.

[bearriver]

Jimbo's controller thread has discussed the ground, or lack thereof in that model of scr. It's worth a read as it's not very long.

I'd use a grounding terminal bus bar like in a breaker panel, or a terminal block to keep things tidy and secure inside the box. Got myself a 11kw controller in a small plastic enclosure. I used a 4-pole 50a terminal block in and two 30a 3-pole terminal blocks going out. Everything stays organized and secure. When running such large amounts of electricity, it's preferable to make all your connections at an appropriately rated terminal.

Here's a diagram of how mine is wired. When reading it, the intersecting wires are actually ganged at the corresponding terminal block with insulated eyelets. There isn't a single wire nut. For example there are two ground wires leading from the 50a terminal block and into the 30a blocks. It not one wire that is spliced into two as seen in the picture.

[bearriver]

Jimbo's diagram, using that same controller. It works for him, it may work for you too.

[thisguy]

I looked at that thread and since I'm using a plastic box it's a little different. I'm just horrible when it comes to understanding electricity.

I think I might just pick up a metal box, makes this type of problem easier