How complicated to switch 3 prong to 4

[Oceanbear1]

Hey guys,

I have been googling this for a little while, but haven't find an answer that I think quite fits what I'm asking.

My wife and I are in the process of buying a house, and once we do I want to build an electric set up. There's not enough room in the box for a dedicated line, so I was going to steal from the drier when brewing.

The thing is the drier plug is 3 prong vs a 4 prong. I would really like the functionality of a 4 prong, so I was wondering just how complicated this is to change out. Would it require an electrician or myself ripping through dry wall?

From my understanding the 4 prong separates out the ground wire from the neutral wire. Could that be snaked from the nearby 120v outlet?

Thanks guys!

 

[illin8]

The 3 prong dryer outlet has two hots and a ground (no neutral), most likely fed by 10-2 wire (3 wires inside - 2 hots and ground) so there is no neutral available. If you wanted to change it out you'd have to rip the wire out all the way back to the panel (not a big deal if area of house is unfinished). It would be much easier to design your system using the same three prong plug and grabbing the 120v from another outlet or source, you really can't use another circuits neutral (for a number of reasons). That's what I do...my system is 4 wire (2 hots, neutral, ground) that powers control panel and element. Due to enclosure size and money the only 110v in the enclosure is the PID which can operate on 220v also I believe. I use another 110v circuit for pumps and fan, which use wall switches to turn on and off. Sure it's not all in one control panel but works just the same.

 

[Oceanbear1]

Thanks for the response, but dang. I can get to the back of the drier outlet, but the box is on a finished wall for whatever reason the last person did it, so I would have to let someone rip through that. Not saying that's impossible, but it will take more convincing of the wife

 

[mirthfuldragon]

You are asking yourself the wrong question. Bite the bullet and plan on upgrading the panel. A full panel usually means there is at least one circuit somewhere that is overloaded.

Electrical demands are only going to keep going up in the future - in the next two decades, electric cars (and their respective charging demands) are going to increase in popularity. You may want to install a garbage disposal, treadmill, laser printer, or any of a dozen things that demand a higher amperage or a dedicated circuit.

I am also surprised your inspector didn't point the issue out - a full panel is at least a cautionary sign, like surface mold or poor drainage.

Also, drywall is very much a DIY thing - ripping it out and replacing it can be done in a weekend and is not that much more complicated than painting.

If your electrical is in conduit, replacing the 3-wire by adding a 4th is relatively simple.

 

[Oceanbear1]

You are asking yourself the wrong question. Bite the bullet and plan on upgrading the panel. A full panel usually means there is at least one circuit somewhere that is overloaded.

Electrical demands are only going to keep going up in the future - in the next two decades, electric cars (and their respective charging demands) are going to increase in popularity. You may want to install a garbage disposal, treadmill, laser printer, or any of a dozen things that demand a higher amperage or a dedicated circuit.

I am also surprised your inspector didn't point the issue out - a full panel is at least a cautionary sign, like surface mold or poor drainage.

Also, drywall is very much a DIY thing - ripping it out and replacing it can be done in a weekend and is not that much more complicated than painting.

If your electrical is in conduit, replacing the 3-wire by adding a 4th is relatively simple.

We haven't had the inspection yet, I'm probably getting ahead of myself. We just got under contract yesterday. Just replacing the box outright is something I have considered, but was hoping to avoid that cost. Its like the one thing we had to compromise with the house.

 

[LarMoeCur]

We haven't had the inspection yet, I'm probably getting ahead of myself. We just got under contract yesterday. Just replacing the box outright is something I have considered, but was hoping to avoid that cost. Its like the one thing we had to compromise with the house.

Talk to your agent and inspector. In my mind a full panel means something changed from the original. I'd bet the owner has added a circuit or two and should have replaced it with the addition of those circuits. I'd tell your agent that you feel the panel needs to be replaced. Maybe the owner will kick the price down a few thousand to cover a new panel. It's worth asking the question.

 

[Oceanbear1]

Talk to your agent and inspector. In my mind a full panel means something changed from the original. I'd bet the owner has added a circuit or two and should have replaced it with the addition of those circuits. I'd tell your agent that you feel the panel needs to be replaced. Maybe the owner will kick the price down a few thousand to cover a new panel. It's worth asking the question.

Thanks I like your advice, I'll talk to my agent about that

 

[SoulToast]

The NEC changed around 2000 to require that 240v dryer outlets are two hots, a ground, and a neutral. So you may have a case for requesting that be changed post-inspection. Certainly easier than having it done after the fact.

I'd recommend being on hand for the inspection, if you can. Strike a balance of not being underfoot and taking an interest (as well you should, it's your new home!) and the inspector may redline a few more things that would otherwise pass.

We just moved a couple weeks ago, and our inspector outlined stuff I was sure was gonna be on my shoulders. Worth a shot to avoid the expense if possible.

And unless you're carrying a license, you may run into insurance problems with diy LX if there's ever a problem. At least the difference between a check and a fight.

If your dryer is 3 prong, changing that plug is no big deal. I just did a 3-4 conversion here at the new house, and spent more time fighting the strain relief than the cord wiring.

 

[Addiktion]

What I did to solve this 3 to 4 Deal that's ongoing blah blah is take a spa breaker and jump neutral to ground in the spa breaker. the spa breaker uses a drier plug and goes into my wall. So I have 3 wires going in and 4 wires going out. GFCI works too. I had a leak and it got my connections wet and breaker popped instantly (before I even noticed the leak). There's going to be 500 responses on why not to do this but it works for me and I don't have to tear out my wall. Also driers had to run this way anyways to power the 120v inside of them. So same same but different.

 

[Addiktion]

A quick add on to my deal is I had hot-hot-neutral on my 3 prong outlet. If you have hot hot ground I don't think you can do this? But that I'm not sure.

 

[triethylborane]

The NEC changed around 2000 to require that 240v dryer outlets are two hots, a ground, and a neutral. So you may have a case for requesting that be changed post-inspection. Certainly easier than having it done after the fact.

1996 NEC, note the requirement is only for new installations. So, if this is a home built prior to 1996 NEC and has a 3 prong outlet, inspector 9 times out of 10 won't write it up as a deficiency, at most they will recommend 4 conductor branch circuit. Besides, it is cheap to convert a new dryer with 4 prong to 3 prong (which is NEC approved). I don't see it being worth more than $30 in negotiations.

 

[Addiktion]

I went through the exact same thing. I just bought my house and it was built late 80's early 90's. It went right through inspection without question. So for me my garage is finished and I would be ripping all sorts of drywall down to add a fourth wire. so at home depot they had a spa breaker 80 bucks, less than 12" of 10 AWG wire and done.