Opinions and/or suggestions wanted on my controller design

[ragincajun97]

I've done a lot of reading through this forum and have decided I want to move to an electric element. My pot is a 30qt stainless turkey fryer pot so it's not big but I would like to go 240V 3500w initially but give myself an upgrade path in case I go bigger, possibly a keg if I can find one. My power supply will be a 240V-50A RV hook-up and a 10/4 50' cord will reach my back patio and my garage. I have a dryer cord that I can use to connect the element back to my controller box and obviously the white wire will not be used. I plan on using a dry box to mount it all in. Grounding the pot will be a bit messy but I think a grounding clamp around a handle will work. I don't like having a dangling wire just for aesthetics and danger of snagging it. I'll have to be careful. I'm going to pull the trigger on stockpiling my hardware soon so I'd appreciate any constructive criticism or a thumbs up from the experts here.

[NZChris]

How are you going to seal the lid?

[Yonder]

Yeah, go with an analog ammeter. Digital ones burn out the screen under loads like you’re going to put it on. My 2c based on experience.

[NZChris]

I've had trouble with digital readouts. I have recently bought the same one and just tried it out now. Like others I've tried with the same type of controller, the reading I'm getting doesn't make sense, it should be saying 90V, but it's saying 47V.

I've made a 0-100% paper scale and stuck it under the knob and use that rather than using digital or analogue gauges.

[NZChris]

To add to that, I just tried a new Chinese analogue Volt meter and that tells me I'm getting 210V after the controller, (set at 39%), and 240V prior to the controller. No Amp or Volt meters I have bought in recent years make sense when used with this type of controller, which is why I have resorted to using the dial position rather than meters.

I do have a forty year old German made moving magnet Ammeter that appears to work accurately with them.

[Yummyrum]

Umm , where will you be connecting the condenser ?

BTW , like the addition of a lid ground .

[ragincajun97]

I should have prefaced my post noting I have been using propane on my setup for a few years now and have lid sealing (Teflon tape/clamps) and condenser (worm bucket) functioning properly and safely.

Thanks for the tips on the digital voltmeter/ammeter. It was more of a curiosity on what it would be doing at a given time during a run. One less thing to wire.

Currently I heat up somewhat quickly then dial back the flame once I feel it working through my lyne arm to the worm. I'm hoping to have that same control with electric.

[Yating_Ju]

There is no reason a good quality digital voltmeter won't work if you wire it well and if you operate it within specifications. They are used in many industries with different types of load.

[seabass]

Is your 240v breaker GFCI? If not, you'll need to either replace it with one or put one in your box. To keep it portable, I used one in my box with the breaker acting as my power cutoff.

Also, several people have said their scr has sufficient cooling, but mine got ridiculously hot with the 5500w element. Considering that they tend to fail opened from overheating, consider additional cooling for the scr chip. I just screwed my scr into an old computers heatsink. They come with very tiny heatsinks.

[cranky]

I guess I'm in the minority but I've never had a problem with my digital meter, maybe it's because I have a spare sitting here ready to go if it does fail.

As far as grounding, I have a copper grounding lug soldered to my boiler near the element.

[ragincajun97]

Is your 240v breaker GFCI? If not, you'll need to either replace it with one or put one in your box. To keep it portable, I used one in my box with the breaker acting as my power cutoff.

My 240 is not GFCI. I had read a couple of folks who said proper grounding makes GFCI redundant. Probably a good redundancy since I'd prefer not to fry doing this. A 30A GFCI breaker for my panel will set me back ~$80. I'd be interested in having one inside my box as the on/off switch but need to do some more research on mounting it properly.

I've seen spa panels online for $50. Has anyone ever used one as their controller box? It might be cramped with the hardware that's built into it but the one I saw is 10x7x4 which might work.

[bluefish_dist]

Looks ok to me. I have had good luck with the $10 power meters on eBay. I have run 4 different ones for 2+ years, no failures. I prefer the ones with a built in power reading so you don’t have to calculate it. The trick seems to be the lone voltage has to be before the ssr like you show. Then take the amps clamp style on one of the legs to the element. If you put the volt tap after the ssr they burn out quickly.

[seabass]

Is your 240v breaker GFCI? If not, you'll need to either replace it with one or put one in your box. To keep it portable, I used one in my box with the breaker acting as my power cutoff.

My 240 is not GFCI. I had read a couple of folks who said proper grounding makes GFCI redundant. Probably a good redundancy since I'd prefer not to fry doing this. A 30A GFCI breaker for my panel will set me back ~$80. I'd be interested in having one inside my box as the on/off switch but need to do some more research on mounting it properly.

I've seen spa panels online for $50. Has anyone ever used one as their controller box? It might be cramped with the hardware that's built into it but the one I saw is 10x7x4 which might work.

The spa panels have built in GFCI, so that'll work. Some might say it's redundant, but my life isn't.

[ragincajun97]

Is your 240v breaker GFCI? If not, you'll need to either replace it with one or put one in your box. To keep it portable, I used one in my box with the breaker acting as my power cutoff.

My 240 is not GFCI. I had read a couple of folks who said proper grounding makes GFCI redundant. Probably a good redundancy since I'd prefer not to fry doing this. A 30A GFCI breaker for my panel will set me back ~$80. I'd be interested in having one inside my box as the on/off switch but need to do some more research on mounting it properly.

I've seen spa panels online for $50. Has anyone ever used one as their controller box? It might be cramped with the hardware that's built into it but the one I saw is 10x7x4 which might work.

The spa panels have built in GFCI, so that'll work. Some might say it's redundant, but my life isn't.

I agree wholeheartedly. That's why I'm here.

[ragincajun97]

Thanks for all the good advice. I have a spa panel in hand and am starting to collect parts. I want to use the spa panel as my controller box and am a bit cramped for space. I have a wiring question for the SCR controllers linked below. Both only have an input and output for one hot wire. From extensive reading in the electric forum, I think these will wire similarly to a 240V SSVR, One hot wire through the SCR and the other hot wire to the element will complete the circuit and allow the controller to properly adjust the power to the element. If this is incorrect please take it easy on me. I think I can squeeze an SSVR and heatsink in there if a better option. I'm going for a 3500w 240V element.

https://www.ebay.com/itm/New-10000W-220 ... 1438.l2649

https://www.aliexpress.com/item/4000814 ... hweb201603_

[Yummyrum]

You are correct

[StillerBoy]

Just a word of caution..

If you are going to buy one of the SCR, buy the one off ebay.. the ebay one is 10000w vers the other is only 8000w.. and there's a recommendation to use only half power for long period of time, whatever that mean.. so the 10000w one will also generate less heat went attached to the 3500w element..

Mars

[ragincajun97]

I finally collected all my parts and started configuring the spa panel box for my controller. I have included a pic of the guts of it. The thin black and red wires that are hooked to the line inputs will go to the voltmeter/ammeter. The short white jumper wire (I need to color it with a red marker for safety) goes from one leg of the breaker to what I assume is the input of the SCR. There are no clear markings for in/out on it and that has me a bit worried. The other hot leg will go directly to the element and has the CT around it. The SCR is not mounted but it will achieve grounding when it is through the box. Any thoughts on the wiring?

[Oldvine Zin]

It's starting to look good, you will have to run a neutral wire in your feed to make that gfci work properly, that's a good thing because in doing so that will provide you with 110 VAC in your box. Very handy for adding fans and other goodies.

Be safe
OVZ

[Oldvine Zin]

Oh your wiring looks a little messed up, only one leg of the hot side should go through the control board. Your wiring prob will fry that board also never use a white wire on the hot side.

Be safe
OVZ

[jonnys_spirit]

I’d prefer a twistlock on the element connection. Looks great!

Cheers,
-jonny

[Oldvine Zin]

Yea looking closer I think that it is wired OK the short white wire was what confused me
6 gauge wire I hope??

Stay Safe
OVZ

[Tennessee_Spirits]

GFCI connect between the hot and neutral lead and sense inequality in current flowing in these leads. Trip current is about 5 ma, so it takes little inequality to interrupt the circuit. It is typically sensing a leak to ground. The ground lead or safety ground is connected at the entrance panel to a rod in the ground that is usually 8 feet long and copper clad. It has a low resistance to a reference or theoretical ground.

I had a panel installed in my brewing area and found that the licensed electrician was reluctant to install a CFCI breaker as the NEC did not require it because it states that GFCI must be used outdoors and within 3 feet of a faucet. I found that for the most part the safety ground is designed to protect the panel and attached equipment. A CFCI is designed to protect the operator (me).

I bought the 30 AMP GFCI myself and the electrician had no reluctance to install the unit once I had bought it.

I personally wire all elements and make sure the safety ground (green lead) is connected to the metal case that grounds the pot via the tri-clamp. Note that if the tri-clamp is not there the pot could be 'hot'. Of course water in the pot will spill, so it is pretty safe in use.

Watch this video by Electoboom on youtube. He is very funny to make the show work but actually serious electrical engineer who understands the importance of GFCI. Be safer than the code.