Using a 3-wire Dryer Outlet?

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GParkins

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If you live in a house old enough to have a 3-prong dryer cord, this may help:

For those of you either using, or contemplating using, your dryer outlet to power your brewing rig, I have come up with a basic design that allows you to have GFCI protection for the brewing rig and keeps a handy receptacle for your dryer if you have an older dryer outlet with only three prongs.

NOTE: This is a hack, and not necessarily compliant with your local building codes. It would be much better to replace the feed cable to your dryer outlet. It also doesn't prevent you from trying to dry a load of clothes in the middle of a boil. If common sense doesn't prevent you from doing that, there isn't much I can say that would.

Repeat Note: DO NOT ATTEMPT TO USE YOUR DRYER AND YOUR BREWING RIG AT THE SAME TIME.

Please do not ignore the first four words of the repeat note.

All warnings aside, this could help save a buck or two going to an electrician's monthly boat payment.

Dryer Outlet Box.png
 

dkennedy

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I opted to wire a dryer cord onto a spa panel, mostly for portability (annoying habit of moving every 5 years or so). This would be a bit more elegant though.
 

Thedutchtouch

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it seems like you're just using the dryer as a fancy bridge between ground and neutral (the way 3 wire dryers are/were wired)- you could accomplish the same thing with a small length of wire within your sub panel, or is this just so you don't have to unplug the dryer to plug in the brewery?
 
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GParkins

GParkins

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It's more to provide a GFCI-protected power supply for the brewery and still retain the original dryer outlet and dryer cord. In my case, it's only temporary hack to power my 50A brewery with available 30A power. I need to keep digging through the sofa to come up with the money to have a 100A subpanel installed in my garage. The brewery will get a dedicated power supply from that panel. Until then, this is a way for me to have the GFCI protection required for the brewery supply. Limping along with only one element at a time is better than not brewing.
 

IslandLizard

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It's more to provide a GFCI-protected power supply for the brewery and still retain the original dryer outlet and dryer cord. In my case, it's only temporary hack to power my 50A brewery with available 30A power. I need to keep digging through the sofa to come up with the money to have a 100A subpanel installed in my garage. The brewery will get a dedicated power supply from that panel. Until then, this is a way for me to have the GFCI protection required for the brewery supply. Limping along with only one element at a time is better than not brewing.
How are you powering a 50A brewery with a 30A circuit? Only running one element at a time?

What kind of GFCI breaker did you use? Like one from a spa panel?
 
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GParkins

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Yes, I'm only running one element at a time until I can have a subpanel installed.

Double-pole GFCI breakers are readily available at Home Depot, Lowe's, etc. Here's a link to a 50A unit.
 

IslandLizard

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Yes, I'm only running one element at a time until I can have a subpanel installed.

Double-pole GFCI breakers are readily available at Home Depot, Lowe's, etc. Here's a link to a 50A unit.
Yeah, that's what I thought. Those main panel GFCI breakers (still) run nearly $200. That's why most people buy a $70 spa panel instead.

Do you have enough capacity on your main panel to add a 100A subpanel to it? I'm asking because we have a 200A service but with the heat pump and air handler at 120A already, Electric range @50A, Dryer @30A, and so on, a 100A extension would push us over the limit. Even adding a 50A spa panel is border line.
 

itsnotrequired

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this will meet code as long as there are not any 120v loads in the brew panel. if 120v loads are there, the ground conductor back to the panel is now a normally current carrying conductor, a code violation. it will 'work' but can be dangerous, especially if that ground conductor back to the panel is uninsulated.
 

lschiavo

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Do you have enough capacity on your main panel to add a 100A subpanel to it? I'm asking because we have a 200A service but with the heat pump and air handler at 120A already, Electric range @50A, Dryer @30A, and so on, a 100A extension would push us over the limit. Even adding a 50A spa panel is border line.
Who told you it would put you over the limit? I highly doubt it would. There are service calculations that determine the size of a service entrance. It's not just about adding up the value of all your breakers. A 40 circuit panel could have 800A worth of 1 pole 20A breakers that says nothing about the actual load connected. Plus, none of the larger loads you mention would be considered continuous loads so they could be derated.

I have a 100A service on my house with an outdoor main panel. From that I have two 100A subpanels. One in my shop and the panel in the house. My brewery can potentially draw near 80A and I've never tripped a breaker.
 
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GParkins

GParkins

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Who told you it would put you over the limit? I highly doubt it would. There are service calculations that determine the size of a service entrance. It's not just about adding up the value of all your breakers.
Concur. There are usage factors that go into determining how to scale a system. The formal document is called a Load Analysis, and they can get pretty complicated. Bottom line is that you can't bake pizza, boil four soup kettles, dry a load of clothes, take three hot showers, set your thermostat to 85 in January, and run a HLT and boil kettle all at the same time. At the end of the day, your main breaker will let you know when you've gone too far.
 

itsnotrequired

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Concur. There are usage factors that go into determining how to scale a system. The formal document is called a Load Analysis, and they can get pretty complicated. Bottom line is that you can't bake pizza, boil four soup kettles, dry a load of clothes, take three hot showers, set your thermostat to 85 in January, and run a HLT and boil kettle all at the same time. At the end of the day, your main breaker will let you know when you've gone too far.
the nec is actually quite explicit on how to size a minimum service for a residence. it is a straight-forward calculation that dictates and takes into account specific usage factors. no doubt if you turned every appliance on, plugged a bunch of stuff into receptacles, etc. that the main could trip but that's okay. it is such an unlikely event that the nec doesn't make you plan for it. of course, the nec only dictates a minimum service size, certainly acceptable to go bigger but the utility company may make you pay an additional fee for something bigger than required.
 

IslandLizard

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Who told you it would put you over the limit? I highly doubt it would. There are service calculations that determine the size of a service entrance. It's not just about adding up the value of all your breakers. A 40 circuit panel could have 800A worth of 1 pole 20A breakers that says nothing about the actual load connected. Plus, none of the larger loads you mention would be considered continuous loads so they could be derated.

I have a 100A service on my house with an outdoor main panel. From that I have two 100A subpanels. One in my shop and the panel in the house. My brewery can potentially draw near 80A and I've never tripped a breaker.
No, it wasn't an exact calculation, but a predictive load based estimate I did a few years ago when we looked at adding a garage/hot tub room/brew area. I probably was a bit conservative there.
 

lschiavo

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I see quite often around here that people are afraid that their service is not big enough to add an electric brewery. I bet that in practically every case it is.

One way I explain to customers occasionally is to look at what it would cost if you were actually fully loading your service.

200A * 240V * 24H * 30days = 34560kW-h
Multiply that by say 13 cents per kW-h would cost nearly $4500/month.

If you're paying anywhere near that, you maybe should upgrade.

Of course, this is an average and does not account for peak loading but it gives some perspective...
 

itsnotrequired

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and remember, the service amperage is at 240v, not 120v. so if someone with a 200 amp service has no 240v loads and only 120v loads, there is actually 400 amps worth of juice available.
 
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this will meet code as long as there are not any 120v loads in the brew panel. if 120v loads are there, the ground conductor back to the panel is now a normally current carrying conductor, a code violation. it will 'work' but can be dangerous, especially if that ground conductor back to the panel is uninsulated.
This is a solid point. Something to consider @GParkins.
 
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GParkins

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Good point, @itsnotrequired . There are the two pumps and the 12v power supply that run on 120VAC. Fortunately, the cable running back to the panel is 10/3 Romex without a bare copper ground (or at least it didn't get brought into the box where I could see it) The color code is red/black/white. I've never seen that combo without a ground wire before.

Edit: The box is NM, but the outlet face bracket and the trim plate are metallic.
 
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GParkins

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the nec is actually quite explicit on how to size a minimum service for a residence. it is a straight-forward calculation that dictates and takes into account specific usage factors.
The load analyses that we do are required to evaluate different scenarios. The company I work for does power distribution on superyachts. When you have a 150' boat, the load scenarios differ wildly depending on summer/winter (heat strips in all of the air handlers), crew only, under way, owner + guests at anchor, etc. All of those calculations are used to determine generator and shore power capacity sizing, etc. It gets a little nuts sometimes.
 

itsnotrequired

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The load analyses that we do are required to evaluate different scenarios. The company I work for does power distribution on superyachts. When you have a 150' boat, the load scenarios differ wildly depending on summer/winter (heat strips in all of the air handlers), crew only, under way, owner + guests at anchor, etc. All of those calculations are used to determine generator and shore power capacity sizing, etc. It gets a little nuts sometimes.
NEC 90.2 Scope

(B) Not Covered

(1) Installations in ships [...]

:D
 
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GParkins

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Dunno about breweries, but I've been on some that had 400A, 600VAC 3-phase buses. Kinda makes you careful about where you stick your screwdriver.
 
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