Grounding an element in a plastic cooler

I think this should work but I wanted to double check before I go using my body to complete any circuits.

I'm going to make a hlt out of a 10g cooler with a 2000 watt heating element. I was planning on cutting a rectangular hole in the outside wall and remove the foam insulation in that rectangular hole and place a metal electrical box in that hole. So the element would be housed in that electrical box and I could attach the ground wire to that box.

It would be very similar to the Electric Brewery did it http://www.theelectricbrewery.com/heating-elements?page=7.

Of course I'm still going to use a GFI but will this setup keep me safe?

As long as your element is grounded to something metal, yes you'll be safe.

Right, it should be as the element will be in the metal box and the metal box will be grounded.

But don't you have to ground the water? That is why most tuns with elements are metal. All you would do is be grounding the element and if it broke and you were somehow the shortest ground then grounding just the box would not work.

How do you ground the water? If the metal box is grounded then the element which would be attached to the box should be grounded too. How else could I ground the water in a plastic cooler?

If you ground the base of the element, it extends into the water grounding the water.

Wort isn't conductive so you're not "grounding the water". Ideally, you want to ground any touchable metal surfaces. In your cooler's case there really isn't any except the element itself so ground to the threaded portion and that box.

jkarp said:

Wort isn't conductive so you're not "grounding the water". Ideally, you want to ground any touchable metal surfaces. In your cooler's case there really isn't any except the element itself so ground to the threaded portion and that box.

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I'm not a scientist but I can't believe that wort is not conductive to some degree. It has minerals, it is not pure H20.

This is for an HLT, which won't have wort in it. If you ground the base of the element (which is touching the water) then you will ground the water.

samc said:

I'm not a scientist but I can't believe that wort is not conductive to some degree. It has minerals, it is not pure H20.

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So pull out your multimeter and test. I did.

As long as your element is grounded to something metal, yes you'll be safe.

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What? This cannot be true. The whole point of grounding is that it ultimately has to go to the ground. Just connecting it to something metal doesn't help if that metal is not in turn connected to ground.

weirdboy said:

What? This cannot be true. The whole point of grounding is that it ultimately has to go to the ground. Just connecting it to something metal doesn't help if that metal is not in turn connected to ground.

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This is true. Your cord will carry an equipment ground from the power supply. This should be connected to the box...grounding the box. The element should be "bonded" to the box either by threading it in or some other means of making it electrically joined with the metal of the box.

All metal components of a system should be grounded and bonded together. If you think of touching a hot wire to a piece of metal in a system...if it is not grounded or bonded it can become energized and if you touch it you become the path to ground.

You cant test wort with a multimeter. There are a lot of things out there that will not show continuity, for example an aluminum can, yet electrical wires can be aluminum. You cant just ground the threads and hope that continues through to the wort. But you can try and see what happens.

PurpleJeepXJ said:

You cant test wort with a multimeter. There are a lot of things out there that will not show continuity, for example an aluminum can, yet electrical wires can be aluminum. You cant just ground the threads and hope that continues through to the wort. But you can try and see what happens.

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Wow. OK boss.

I'll just ignore those mA readings then.

jkarp said:

So pull out your multimeter and test. I did.

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Just to be sure we are on the same page, do you think that sitting in a bathtub of wort while someone throws a live wire 110/220 into the tub will cause you any trouble?

ascha, If the hole you drill in the box is slightly larger than the diameter of the threads, the meat at the "base" of the heating element will rest against the metal of the box. In pic 8 at the top, you'll see a post. You'll need a green self tapping (grounding) screw (if your box hasn't been opened at the store, it should come with one). Thread that into the post. If your cord has solid conductors, wrap the green (or bare copper) wire around that screw and tighten. If your cord has stranded conductors, use ring or spade terminals to attach your wires to their respective terminals. If it has a bare copper conductor, you could use some heat shrink on it to reduce the risk of it accidentally coming in contact with a hot wire. These boxes rae painted to reduce the effects of corrosion, so you might want to peel away some of the paint (where the element meets the box) to get a better metal to metal contact. This should make everything grounded. Hope that helped. Pete
PS - Almost all liquids are conductive to a degree. According to Mythbusters, you can pee on the third rail and not get shocked. I won't be field testing this anytime soon...

samc said:

Just to be sure we are on the same page, do you think that sitting in a bathtub of wort while someone throws a live wire 110/220 into the tub will cause you any trouble?

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Too many variables to say for certain. I'm not volunteering.

The conductivity of wort would depend on the quantity of dissolved ionic materials. As wort (hopefully) isn't very salty, it should be a relatively poor conductor. I saw 3-4mA @ 120V from an open hot to a grounded kettle through wort. It wasn't even enough to trip the GFCI.

Like all electric threads here at HBT, this one has gone off the rails. The OP should ground all touchable metal surfaces AND use GFCI.

jkarp said:

The OP should ground all touchable metal surfaces AND use GFCI.

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This is all that was needed said, some of the debates on here leave me wondering how many HBT members get get there d!cks blown off or do damage to their property. Some scary replies from an electrical engineers viewpoint.

aahhh engineers. It works out on paper so it must be....except when it's not even close in the real world Just stirring the poo.

IrregularPulse said:

aahhh engineers. It works out on paper so it must be....except when it's not even close in the real world Just stirring the poo.

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I am more practical than you may think. No pocket protector. Dont get me wrong I would never tell someone they are not "educated enough" to build these systems, thats what they are here for. I have just seen some answers and questions over time that scare me. Should scare anyone with any knowledge of electricity. My system is safe and built to well within its limits. I do this for a living in our lab so I have the experience points to back up the paper.