Lets see, a breaker box at the hot tube with a 1 breaker in it for the hot tube so lets start there.

The box needs replaced to accept two breakers, on for the hot tube and one for the feed to the greenhouse. So a new box and a 20 amp breaker, you don't protect 12 ga wire with a 50 amp breaker and a 20 amp breaker is required.

PVC offset fitting, PVC electrical conduit, and a PVC 90 degree long sweep into the ground at least 24 inches deep. A trencher, or do you expect it to be hand dug? And the 12 gauge wire, which the electrician doesn't buy from amazon. Red caution electrical wiring tape placed above wire. Conduit straps securing conduit out of the box (required by code), wire nuts, maybe electrical putty and screws, bolts, nuts, and electrical tape.

at the greenhouse nearly everything above with exception of a disconnect instead of a breaker box. If the electrician owns the trencher there will be a fee not much different than a rental fee because it eventually needs paid for ovrr the years.

I believe $400 for materials is about right, and the stuff he uses doesn't come from amazon but a wholesale electrical supply outlet, plus his mark up.

Get an electrician on-site before you hurt somebody!

- 12 gauge wire is WAY undersized for a 50 amp circuit.

Get an electrician on-site before you hurt somebody!

@HU-867564120, I actually majored in electromechanical engineering, but that was some 30 years ago! LOL I've never worked in this particular field, though. My focus was more on robotics and circuit board design. But I know my way around pretty well.

12 gauge wire is WAY undersized for a 50 amp circuit.

Agreed, that was just a quick search for a breaker. The heater pulls a max of 31A, so 10G would be sufficient. But I'd be putting in a 40A breaker, so I'd run 8G to be safe.

The box needs replaced to accept two breakers, on for the hot tube and one for the feed to the greenhouse.

@kevin9408, the box has room for more breakers, that shouldn't be an issue. The electrician that came out looked at it and confirmed that it doesn't need to be replaced.

You can see here that it has room for more:

PVC offset fitting, PVC electrical conduit, and a PVC 90 degree long sweep into the ground at least 24 inches deep.

Is there a reason to not feed it through the conduit that's already there?

Funny enough, though, the sweep doesn't go underground at all! It just leads to under the deck, and then the wire to the hot tub is laying above ground. It was like that when I bought the house about 20 years ago.

A trencher, or do you expect it to be hand dug?

The quote was to lay it above ground under the deck, then bury it a few inches deep (basically just under the mulch) for the 20' from the deck to the greenhouse.

And the 12 gauge wire, which the electrician doesn't buy from amazon.

Let's step that up to 8G wire, not 12G. And a 40A breaker.

Is there a reason to be concerned with the quality of wire from Amazon or Lowes? I'd likely buy it by-the-foot at Lowes.

With this expanded list, I'm still coming up to under $200. Unless there's something very special about the contractor wire that makes it worth 2-3 times the Lowes price?

The real issue here is that I simply don't have $700 for the job ($400 in materials, $300 for labor). I had a maximum budget of $500 for the electrician, because I still have to buy the heater.

I have a 110V heater in the greenhouse now, but it's just not enough. The most that I can get with my 15A breaker and extension cord is 5000 BTUs, and I need closer to 30,000! We're already having some 20 degree nights, so I'm going to lose all of my plants if I don't do something. My option is to either do it myself, or just let everything die.

Can you really get a 30,000 BTU heater that only draws 31 amps? Seems like you may need a 50 amp circuit and 6 AWG cable?

And was the electrician really going to "bury" the UG cable under a few inches of mulch?

Maybe you should be thinking about a propane heater. Or running two 240 volt, 30 amp extension cords to two heaters?

You still don't show that you know what you are doing; call an electrician. Because of the continuous load rule, you need to downsize the wire rating 80%. You need 8 gauge wire and s 40 amp breaker.

Can you really get a 30,000 BTU heater that only draws 31 amps?

@dennisgli, this is the one I was looking at:

https://www.amazon.com/gp/product/B07QM2H5TR/

The manual says 25,589 BTUs, and max power is 31.3A:

https://m.media-amazon.com/images/I/91owGeLBLlL.pdf

I originally considered this one, but didn't think it was worth paying double:

https://www.amazon.com/Comfort-Zone-CZ260ER-Output-Ceiling/dp/B076FNKBTQ/

And was the electrician really going to "bury" the UG cable under a few inches of mulch?

Yup. He specifically said that he would put it "just low enough so that I wouldn't hit it with a weedeater or anything".

Maybe you should be thinking about a propane heater. Or running two 240 volt, 30 amp extension cords to two heaters?

I originally considered propane, but I'm afraid that the cost for that would get out of hand. I HOPE that the greenhouse will retain enough heat that the increased electric bill won't break the bank.

You still don't show that you know what you are doing; call an electrician.

@HU-867564120, you're confusing "asking to double check with others" with "don't know what you're doing". It's 3 wires and a plug, it ain't rocket science.

I appreciate your concern, but when the money's simply not there then my options are limited.

The list of materials they gave was (copy-and-paste from their email):

8/2 UF Wire-60 feet

1” PVC Pipe- 10 feet

1” Rigid 1 Hole Strap

2 Pole 40Amp 120/240V Breaker

60 Amp AC Disconnect 120/240 Volt

2- 1” Electrical Topaz Screws

I would be happy to pay for the labor, but I just can't figure out why they're charging $400 for materials when the same materials at Lowes are less than $200. There's a question of whether the wire they intended to supply is of higher quality, but is there that big of a quality difference to justify spending $200 more?

Because of the continuous load rule, you need to downsize the wire rating 80%. You need 8 gauge wire and s 40 amp breaker.

I agree. Please note that I said this 5 hours ago:

" The heater pulls a max of 31A, so 10G would be sufficient. But I'd be putting in a 40A breaker, so I'd run 8G to be safe."

and

" Let's step that up to 8G wire, not 12G. And a 40A breaker."

Time for a recap Jason. If total continuous current draw is 31 amps you didn't mention the voltage., 120 or 240? if the heaters are 120 volt going with 240v heaters to get the same BTU's would cut your load in half and also you wire size. I'm assuming you're talking about 120 volts so I'll work from that, so the supply breaker and wire needs to rated at 125% of load. So a 31 amp load needs a wire good for 39 amps and a 40 amp breaker, so 10 ga wire doesn't come close and 8 ga. wire is required. Using a voltage drop calculator for a 120 volt run 60 feet long of 8 ga wire with a 31 amp load the voltage drop would be 2.337 volts. The voltage drop would be less than 3% and not critical so 8 ga wire is all that is required with no need to jump up to 6 ga wire.

Lets be clear, a circuit breaker is to protect the wire from overheating, melting the insulation and causing a fire, and not protection of any device drawing power from the circuit.

Running your wire. You can't use any wire in a permanent application and just laid it on the ground, it's against code and dangerous. You can't even lay wire in conduit on the ground and not allowed in a permanent application. To be fair I use a 150 foot 12 gauge extension cord to run a water booster pump and roll it out when needed in the summer and roll up when done, and still kind of dangerous, but OK for temporary use. An outdoor extension cord should have a "W" in the cord type, "STW", SJTW", "SOW" or "SOOW" but meant for temporary use, and a 8 gauge extension cord will be costly. But this would be your easiest alternative, and you can roll it up when not needed. A proper outlet to the box at the house would need to added.

If you want to go with permanent wiring.

Direct burial wire MUST be buried 24 inches deep with a caution tape 12 inches above the wire and UF or UFB wire. The caution tape is for someone who digs they will hit the caution tape first before they get electrocuted, and just nature weeding out the stupid. Using conduit the wire inside needs to be THWN or THNN (some are dual rated as THWN/THNN) and not romex. Wire ran in PVC gray electrical conduit must be 18 inches in the ground, and the 90 degree sweeps up and anything above ground must be schedule 80. Using galvanized Electrical Metal conduit (EMT) rigid or intermediate thickness needs to only be buried 6 inches into the ground.

A temporary extension cord would be the easiest, but If I decide to run permanent wires to my booster pump it would be galvanized EMT buried 6 inches with single wires of THNN.

The wire price and conduit are about the same price as UF-B or a little more but I don't want to dig a ditch 2 feet deep and 150 foot long.

If total continuous current draw is 31 amps you didn't mention the voltage., 120 or 240?

Sorry about that, @kevin9408. I mentioned that it's 220V in the subject, but probably forgot to reiterate it in the post.

Technically, I get 123V on both legs. So 246V.

I used this calculator to come up with the 8G value:

http://www.paigewire.com/pumpWireCalc.aspx

You can't use any wire in a permanent application and just laid it on the ground, it's against code and dangerous.

i did think it was weird that the electrician was going to barely cover it! But since the wiring to my hot tub is the same way, I thought maybe this type of wire is tougher against the elements than I'd assumed.

Either way, it's not a big deal to bury it. I'm running it through a mulched area with well draining soil, so it won't be too hard to dig a trench. I could probably dig 12" with my bare hands! LOL

Using galvanized Electrical Metal conduit (EMT) rigid or intermediate thickness needs to only be buried 6 inches into the ground.

Like this?

https://www.lowes.com/pd/Common-1-2-in-Actual-50-In-Metallic-Emt-10-ft-Conduit/3129551

and presumably this connector:

https://www.lowes.com/pd/Sigma-Electric-ProConnex-1-2-in-Set-Screw-Coupling-Electrical-Metal-Tubing-Compatible-Conduit-Fitting/1000152659

You can see from the list above that the electrician had no intention of using conduit, unless the plan was to barely cover it under the deck and along the fence, then use that 10' PVC to go from the fence to the greenhouse?

Either way, I can swing $60 on it. The total price would still be about 1/3 of what I was quoted :-O

I don't want to dig a ditch 2 feet deep and 150 foot long.

I feel your pain. My plan for this year was to dig a French drain that's about 120' long, but it would have to be 3' deep and 3' wide! And at least part of it would be done by hand because I'm not sure where the septic lines are. It reeeeally needs to be done, but between the cost and time involved I keep procrastinating.

You might want to go with a larger conduit - depending on how many bends.

And don't forget one of these!

It's a straight shot for 40', from the box to the end of the fence. Then one angle (I guess around 135 degrees) to turn it towards the greenhouse.

I might see if I can rent a bender, or even just borrow one. It seems like a waste to spend $50 just to make one bend! LOL

Jason- How big is your greenhouse that you need that many Btu/hr? I've had some below freezing nights already, too. But I'm easily able to keep my 150 sqft greenhouse in the high 30's with my 1500 watt, oil-filled electic heater using only 1/2 its capacity. Of course, I'm not growing tomatoes in there, but I've had no problem in keeping my sensitive plants alive year-after-year using only 750 watts (2600 Btu/hr) throughout the winter. Since it sounds like your project is not on a fast track, what is your bottomline Btu/hr need to keep your plants alive In the meantime?

How big is your greenhouse that you need that many Btu/hr?

20x10x7, so 1400 cubic feet:

https://www.quictents.com/products/20-x-10-x-7-greenhouse

I currently have a 1500W oil filled electric heater like you've described, but at night the temperature has dropped to the 40s! I'm not sure if a lot of my plants are going to survive.

The floor is probably the biggest problem. I put in a thick layer of mulch because pea gravel is too expensive, but long term I'd like to put down a cement floor.

Right now the minimum temperature I need is around 60F. But I start my hot peppers in February, so I'll need it to be in the 70s by then.

Jason, the conduit fill table shows you can pull 3 strands of 8 gauge THWN or THHN through 1/2 inch conduit but will be tight, and may need lubed up to pull it. Yes there is lubricant made for pulling wire through conduit

The conduit you linked to isn't the right kind and is lightweight for indoor use and will rust to nothing in a few years. You will need intermediate (IMC) which is thicker and HOT galvanized for outdoor use. Here is intermediate conduit and fitting for them are exclusively for IMC and RMC (rigid conduit) so you can't use ordinary conduit fittings. You can bend 1/2" IMC by a hand bender but not easily.

The fittings you linked to are for Lightweight EMT conduit and not water tight and not for IMC.. From what I can tell Lowes doesn't carry IMC conduit but does carry RMC conduit (very expensive), and the RMC fittings are also used for IMC conduit. To connect two pieces of conduit you would use these couplings just the way you'd use a black iorn pipe coupling to make them liquid and air tight. Any other fittings you would need would also be for rigid conduit.

this is the wire you would use inside the conduit. 8 gauge THHN wire. Lowe's price is robbery and can be found on rolls for 50 cents to 60 cents a foot other places so shop around.

Awesome, thanks for the info!

The more we've talked about it the more confident I am that I can do this on my own pretty easily, so I think I'll step up to 6G wire and larger conduit in case I need it in the future. I might add in a 120V receptacle, too. I can do all of that and stay well below my $500 budget.

Jason, I have a 1900 sq. ft. garage which includes an air conditioned shop, 240v ac/dc arc welder, tig welder, many power tools, fans, lights, and many gizmos and gadgets humming away, including the outlets supplying the power to my water booster pumps. My feed to the garage/shop is 50 amps from 75' of 6 ga wire.

I think going to 6 ga wire is overkill for your little greenhouse, and even think 8 ga is not necessary. I calculated your heating load for your greenhouse in another thread and believe it came out at 4500 watts using electric heat. A 2 pole 240v feed using 10 ga wire would give you 7200 watts of power, and nearly 5 times the power you're using now for the 1500 watt heater. A 10 gauge 2 pole 240v feed wire will allow you to run two 120v 1500 watt heaters off each pole (leg) with power to spare, or 6000 watts equal to 20,000 btu.

But if you want 8 ot 6 ga 40 or 50 amp feed it's your choice, and money.

I was thinking more along the lines that I might want to add a second greenhouse or something in the future, or maybe add an AC for those late-winter months where it's cold at night but hot in the day. I'd hate to have to run all new wire, so it's better to spend a little more now than a lot more in the future.

Money's tight, but I'm still well within budget. At this point I'll be able to buy the heater out of the electrician's budget, and STILL have money left over :-D

Just to let you all know, I got it all installed today with no problem. It took me about 2 hours, easy peasy.

But I did have one issue that I wanted to share, if just to make you laugh!

The breaker box is next to the house, less than 10' away from the heat pump. So I'm sitting on the ground, I have everything wired and ready to go, and I pushed the breaker in place. Right as I pushed it in the heat pump came on, scared the absolute crap out of me!! LOL I thought the whole thing had blown up in my hand!

I've been there and done that Jason, it makes you chuckle afterward but I bet you weren't laughing when the pump kicked in. Did you need to change your undies? So what size wire did you end up using>

Did you need to change your undies?

For real!!! LOL

So what size wire did you end up using

I went with 6/2, it wasn't much more than the 8/2 that I was going to use and I think it'll give me room to grow. The 8/2 was $1.98 /foot, and the 6/2 was $2.18 /foot; so at 60', it was only $12 more.