Functional Difference between 3- and 4-prong 240V plugs?

[mongoose33]

Still working on setting my system up--a lot of boil controller/mash controller panels have a 4-prong power cord plug.

I'm in the process of running wire from the sub panel to a receptacle; using NMB 10-gauge 10-2 wire (my electrician spec'd this).

Can I terminate that in a 4-wire receptacle or do I have to have a 3-prong receptacle? I'm looking at panels that come with the 4-prong plug.

My understanding--please correct if wrong--is that the functional difference between 3- and 4-prong is a separate ground wire, but that otherwise it's not functionally any different.

So--can I use a 4-prong receptacle? It would be easier to get a panel setup with that rather than having to rewire 4-prong to 3-prong.

TIA!

 

[AnOldUR]

They both have ground. The 4 wire also has a neutral for running 120V things like a pump. Do not use the ground as a neutral. Run 10-3 to the panel and recepticle.

If you use a 4 prong receptive with 10-2, at some point someone will assume it has a neutral.

Definitely not to code!

 

[mongoose33]

They both have ground. The 4 wire also has a neutral for running 120V things like a pump. Do not use the ground as a neutral. Run 10-3 to the panel and recepticle.

If you use a 4 prong receptive with 10-2, at some point someone will assume it has a neutral.

Definitely not to code!

Got it.

Here's what I'm unclear on--a lot of these panels have an output for the kettle element at 240v, plus another for the pump. If I put in a 3-prong receptacle, can that panel still run both the 240v element and the 120-v pump, or do I need to have a 4-wire approach for both those to work?

Sounds like either way I need to trade in my 10-2 for 10-3.

 

[golfindia]

You should show your electrician what you intend to run, and have him or her install what you need. Setting things up based on "number of prongs" could end up being problematic.

 

[mongoose33]

You should show your electrician what you intend to run, and have him or her install what you need. Setting things up based on "number of prongs" could end up being problematic.

I'm running wire, he's doing all the connections. In the end, I just went to the higher level and we'll go from there.

 

[golfindia]

Here is a nice pictorial representation of how AC wiring in your breaker box works.

http://www.thecircuitdetective.com/bkgrd.htm

Hopefully helpful!

 

[augiedoggy]

To keep it simple, if you intend on running 120v devices like a pump and 240v things like the element, than you do in fact want 4 wire (3 conductors and one ground wire) as well as 4 pin nema outlets. 10/3 is what I used...

It can be done with 3 wire but its not right and not to code and the cost difference to do it safely is marginal.

The only place in your house the ground and neutral should come in contact with each other is the main power panel

 

[mongoose33]

To keep it simple, if you intend on running 120v devices like a pump and 240v things like the element, than you do in fact want 4 wire (3 conductors and one ground wire) as well as 4 pin nema outlets. 10/3 is what I used...

It can be done with 3 wire but its not right and not to code and the cost difference to do it safely is marginal.

The only place in your house the ground and neutral should come in contact with each other is the main power panel

Yeah...returned my 10-2 and bought 10-3 and ran that wire instead. Set up for a 4-wire. Ordered a panel kit from Auber. All I'm waiting on now is for the electrician to make connections.

BTW....I finally figured out why I was struggling with understanding 240v. The hot lines in 240 are out of phase, which is why you can do two hots and a neutral. Finally makes sense. I've looked at a lot of stuff online, and almost never, at least in the things I was reading, did anyone mention this. I always love a good how-to, but I also want the theory, the underpinnings.

I'm still going to have my electrician make the connections.