prongs

[dukes7779]

gathering equipment for e-brewing. looking at receptacles and plugs on ebay and amazon but finding varying prices between 3 and 4 prong items but I don't know what the difference is between them. finding both for 250 volt 30 amp ratings.......ugh!

any help is appreciated!!!

 

[wubears71]

3 prong - 2 hots and a ground
4 prong - 2 hots, 1 neutral and a ground.

 

[dukes7779]

so then does it matter which ones I use as long as the male/female match up? what about if input to control box is 4 prong and I use 3 prongs for the elements?

 

[iijakii]

Control box being four prong is needed so you can have a solid ground and connect it to a GFCI breaker/outlet. The element only requires three prong - ground and two hots.

 

[kellzey]

These connectors are available at Home Depot and Lowes. You can go there and touch and feel and it may make more sense seeing both halves together.

Also, the configuration and shape of the prongs changes based upon amp ratings 10A, 20A, 30A, etc.

 

[Budzu]

The purpose of having the 4th wire is to provide neutral as said above, which would be needed if there are any 120 volt components in addition to the 240v components being powered by said plug. The neutral isn't needed for a gfi to function.

So if you aren't powering any 120v stuff, just get the 3 wire and save.

 

[dukes7779]

eventually I will have a pump(s) that would be 120v. I will definitely go with 4 for GFI protection on the power input. amperage depends on what it is powering correct? so if my element is 25 amps I don't/cant use a 20 amp plug and breaker correct?

 

[cscade]

Go 4 wire so you have the option for 120v devices later. If your element draws 25A, and you are only ever going to have one element on at once, use a 30A GFI. If you need 2 elements, you'll need a larger feed.

Breakers protect the devices connected to them by tripping if a heavier load is placed on them than their rating. This prevents properly-sized wire on connected devices from catching on fire, for example. This is also why a breaker will trip if a hot wire touches a ground wire - the potential to ground is unlimited, so the connection draws a ton of amps.

In the case of a GFI breaker, it will also trip if there is a current differential between hot and neutral. A difference implies that current is going to ground somewhere at a low rate... that tends to be a wet surface, or (hopefully not) you.

 

[Budzu]

Here's some info I found:

Do not confuse a neutral wire with a safety ground wire. A 240V GFCI usually has to be connected to the neutral wire of the source cable/line, coming from the breaker panel, to be able to supply the neutral to the load if it requires one, as was described above. If the load does not need a neutral - because it does not have any 120 volt devices such as time-clocks, programmers, etc. - then no neutral wire needs to be run to the load.

However a GFCI needs to have a ground wire from the source so that it can operate correctly to detect fault currents flowing into the safety ground wire coming from the load.

Note that the modern GFCI's other main way of detecting faults is to detect a sufficient difference - usually a difference of only about 30 milliamps - between the current flowing in one "hot" (for example a black wire) compared to the current flowing in the other "hot" (for example a red wire). Such a difference or imbalance must be caused by a leakage current going from one of the hots to ground without going through the protective ground wire: for example from a damp control switch that has cracked plastic insulation to a person's hand and then through his or her body to the damp floor in a kitchen or utility room.