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Alex
Alex, Master Electrician
Category: Electrical
Satisfied Customers: 1716
Experience:  Owner of independent electrical contracting company. Licensed Electrical Contractor in CT.
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I am considering installing a 240V Advantium oven. It is rated

Customer Question

I am considering installing a 240V Advantium oven. It is rated at 30 Amps. I would like to confirm if I need a two pole 220 VAC breaker. Also, what is the best wire size that is safe but not overkill. I will be running the wire over about 30 to 45 feet. Lastly, should I use conduit to protect 220V wiring on the run from the power box?
Submitted: 2 years ago.
Category: Electrical
Expert:  Alex replied 2 years ago.
Hello,

Are you going to be running the wire in the basement? If yes is the basement unfinished or finished? Did you get 30 amp rating from the oven name plate of the oven or?
Customer: replied 2 years ago.
`No, the wire will run from an external panel into the attic and along the same wall to the kitchen. The 30 amp rating is on the GE website under power ratings. Amps 240V/208V is 30.
Expert:  Alex replied 2 years ago.
If it requires 30 amp 240 circuit then you will need 10/3 ( black, white, red, bare ) wire and 2 pole 30 amp breaker. If it draws 30 amps then you will need 8/3 wire and 2 pole 40amp breaker because you can not load the breaker more then 80% of its ratings. In the Attic you do not need to put the wire in conduit as long as you use NM so called romex wire. However where the wire will be outside of the walls you will need to protect it by Putting it in the conduit.

Let me know if you have more questions.
Customer: replied 2 years ago.
Can you clarify between using the 10/3 and 8/3 wire and the 30 amp or 40 amp breaker? You first said if it requires 30 amp 240...10/3. Then you said "If it draws 30 amps then...8/3 wire and 2 pole 40 amp breaker. I do get the 20% safe margin on the breaker, but that extra 10 amps rating won't cause an unsafely high limit will it? The reason I ask is I don't suspect appliance power ratings are in the normal usage range, but maximums. Is that crazy thinking? Also, when you said to use conduit when not in the walls, should I take that to mean running across rafters in the attic, 220V wire should be in conduit?
Expert:  Alex replied 2 years ago.
If the unit actually draws 30 amp then you need 40 amp to accommodate 80% requirement. If manufacturer specs that it requires 30 amp then you should be ok with 10/3 wire and 2 pole 30 amp breaker. If you tell me the watts and volts for that unit then I can definitely tell you what size you need. If you use romex wire it does not matter if its 110v or 220v, in the attic and inside the walls you do not need to use pipe/ conduit.
Customer: replied 2 years ago.
Since it is Advantium, the microwave portion is 975 Watts, but there are also halogen lamps and convection fans and vent fan, but no where else (except for the microwave function) does it give Wattages. So, there is a lot of other powered elements and they didn't make it 240V oven for nothing. With that being said, do you recommend the 8/3 and 40 amp breaker? Is 8 the smallest gauge you would use for 30 amps at 220 or 240V?
Expert:  Alex replied 2 years ago.
If its rated at 30 amp you should be ok with 10/3 wire and 2 pole 30 amp breaker.
Customer: replied 2 years ago.
Also, can you give me a bit of insight into the breaker wiring since there is a neutral wire involved. I will be using the NEMA 14-30 receptacle. Black, Red, White and bare. I think I understand that Back and Red are to be wired HOT and White Neutral. So on the breaker end, where do I tie Neutral?
Customer: replied 2 years ago.
I believe your answer about the 10/3 wire and 30 amp breaker is accurate, but could you just shore up my understanding of why? If the manufacturer rates the appliance at 30 amps, then we should match the performance with a 30 amp breaker since the manufacturer already builds in margin to the 30 amp rating? Would that be the reason why?
Expert:  Alex replied 2 years ago.
That is correct. If you want to be safe run 8/3 that way yOu can gO both ways, 40 or 30 amp. But if the unit is rated for 30 amps it should get 30amp.
Expert:  Alex replied 2 years ago.
If its a main panel the neutral and ground goes to the neutral bar. If its sub panel then there should be ground bar and neutral bar. So neutral will go to the neutral bar ( where the white wires are connected ) and ground to the ground bar ( where the bare and green wires are connected to )
Alex, Master Electrician
Category: Electrical
Satisfied Customers: 1716
Experience: Owner of independent electrical contracting company. Licensed Electrical Contractor in CT.
Alex and other Electrical Specialists are ready to help you
Customer: replied 2 years ago.
Hello, Alex.

I have surveyed the main power panel and the attic and have now adjusted my plan. I believe it will be best to use conduit and come out of the main panel on the outside of the house and go along the side of the house under the eave to the entry point directly in line with where I want the 220 receptacle (NEMA 14-30). Based on our previous discussion, I plan to use 8/3 Romex.

My question now is in regard to conduit and exiting the main power panel and entering the brick directly to where I want to place the receptacle.

1) Is it ok and what is the standard way to come out of the top of the panel with conduit (with regard to interfacing conduit to the panel)?

2) What is the standard for fasteners along the conduit run (one fastener for how many feet or is it standardized)? I plan to fasten to brick or mortar (which is the best?). Also, there is a bit of hardy plank siding just under the eave at the top of the brick, so can I fasten (per standards) at any height along the brick wall that I choose?

3) Do I just drill a hole through the brick/mortar where I want to enter the house and do I run the conduit through the brick and inside of the cabinet where the receptacle will be placed?

4) And finally, can I connect the conduit to the receptacle box to get a solid mount for the box (I don't plan to mount it to a stud but instead have the box in the cabinet with the rear of the box against the back of the cabinet to reduce the amount of wall work to only a pass through hole)?



Expert:  Alex replied 2 years ago.
Are you planning to use PVC or emt pipe?
Customer: replied 2 years ago.
Are they considered equivalent? Do local codes often differ in this matter? I had assumed it must be emt pipe.
Expert:  Alex replied 2 years ago.
Some of the local authorities in force galvanized ( for example NYC ). Mostly you should be ok with running PVC.
Customer: replied 2 years ago.
I would guess the pipe would be the best, XXXXX XXXXX don't know how it compares to pvc regarding difficulty in installation.

Let me know if I am asking for a lot of trouble using pipe, but if not, please answer the questions assuming I will use the smallest reasonable metal conduit (guessing it will be 1/2 inch or 3/4 inch).

Expert:  Alex replied 2 years ago.
1. if you use emt pipe from panel to the outlet box then you do not need to use romex wire. you can use #8 THHN stranded wire ( black, red, white) and green you can use #10 . it might be cheaper.
2. if you use EMT outside you need to use compression fittings, connectors and couplings.
3. By the code it should be secured every 10 ft and 3 ft from outlet box, or panel in your situation.
4. you can definitely use that piece of wood to support the pipe. you can use single hole straps.
5. you will need to support the box to the back of the cabinet.
let me know if i forgot to answer any other questions.
Customer: replied 2 years ago.
Only one thing not answered yet, about the conduit and passing into the house. Should I pass the conduit through the brick and into the receptacle box, or just wire goes through the wall to the cabinet?
Expert:  Alex replied 2 years ago.
It's better if you pass the conduit trough the wall and connect it to the back of the box using connector.
Expert:  Alex replied 2 years ago.
you can use the following LB at the penetration point.

http://www.bptfittings.com/images/products/LB41CGCDUO.JPG
Alex, Master Electrician
Category: Electrical
Satisfied Customers: 1716
Experience: Owner of independent electrical contracting company. Licensed Electrical Contractor in CT.
Alex and other Electrical Specialists are ready to help you
Expert:  Alex replied 2 years ago.
I just realize one more thing. if you are planning to install the outlet in the same cabinet as the oven make sure that it clears the back of the oven. most of the ovens have big room on the top some have on the bottom. just make sure to do not penetrate with pipe and install the box where the back of the oven is deep and will interfere with installing it flush with cabinet.
Customer: replied 2 years ago.
Thanks. Actually, the cabinet is directly above the oven and is where the vent fan ducting is hidden. It is the same location as the 110 receptacle, which I will leave in place and locate the 220 receptacle next to.

Since I was such a great customer, does that mean you might come do the work for me?Cool Just kidding, but you'd be welcome! It's pretty nice in Houston right now.
Expert:  Alex replied 2 years ago.
Yes, pick me up from airport tomorrow :).
Customer: replied 2 years ago.
Hi, Alex.
Getting close to doing the job. I would like to confirm my parts and get a little help on piece parts I don't know.

  1. 2 pole 30 amp Cutler Hammer breaker
  2. 30' 10/3 romex wire
  3. Cutler Hammer panel adapter to come out of the top to PVC. The hole in the top of the panel is 2.5" diameter.
  4. 30' PVC and glue
  5. 5 single hole straps and screws for hardiplank or mortar
  6. PVC compatible adapters for three 90 degree bends. (One 90 degree bend is where I penetrate the brick. Can I use the LB with PVC? What should I use for the other two bends that don't go through the brick? Same thing?)
  7. Sealant for penetration point (Caulk? ? ?)
  8. Adapter for receptacle box (part ???)
  9. receptacle box for NEMA 14-30 (surface mount) Part number???
  10. NEMA 14-30 receptacle

Anything I missed?

sThe picture shows the panel and the outside duct approximately where I will penetrate the wall.graphic



Expert:  Alex replied 2 years ago.
Hello, Are you planning to come out of the top of the panel?
Customer: replied 2 years ago.
Yes, I will come out of the top.
Expert:  Alex replied 2 years ago.
2 things.

1 - most of the outdoor panels and I believe yours does not have a knock outs to enter from the top. Most likely it has from the bottom, so you will have to come out from the bottom.
2. Since you are ruining it outside you can not use romex. It has to be ether THHN wires or UF wire.
Customer: replied 2 years ago.
See item 3. I explained there is an opening in the top of the panel 2.5 inches in diameter with a cap secured by four screws. I just have to find an adapter for that opening.

I was misunderstanding earlier then about the romex. I thought you meant that it was optional to use romex, but possibly cheaper to use THHN in the PVC conduit. I plan to use PVC conduit. In our past conversation, I was under the impression that with emt pipe, I had to use the THHN. Now a question about that.

Is THHN separate conductors or is it four conductors in an insulative sheath? And what is the difference in UF versus THHN. Previously, you had written that I could use #8 THHN for black, red and white and #10 for green.

Customer: replied 2 years ago.
Also, here is a picture of the panel.

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Expert:  Alex replied 2 years ago.
That is for hub for service entrance. You will need to find the hub for the size of the pipe you are planning to use.
THHN are individual wires, so you will need 3 #8 and 1 # 10.
UF is same as romex with one exception that it's good for use outdoors and underground.
I believe the THHN is the best way to go as long as you start with pipe from panel and finish with the pipe in the box. THHN wire can not be run exposed without conduit.
You could come out from the bottom with one connector, short piece of pipe and LB going left. Then 90 and go up to the attic.
Customer: replied 2 years ago.
In summary, a few more questions:
  1. Should I be able to find a hub to come out of the top of the panel to 3/4" PVC?
  2. Then should I use a sweep to make a bend or an LB to go 90 degrees to the left along the eave (outside)? Should I use LB's for every 90 turn?
  3. And after that another LB for the 90 degrees turn back down to the penetration point and a last LB to penetrate the brick?
  4. Finally, when I penetrate the brick is there a common adapter interface for 3/4" PVC to receptacle box?
  5. I also looked again and see the knockouts at the bottom of the panel. Is that preferred, or going back to 1. above, can I find an appropriate hub adapter to keep the path simple?
Expert:  Alex replied 2 years ago.
To be honest i have never checked if they make that because i have always used that hub for service entrance pipe or SEU Cable.
The reason panel has knockouts on the bottom is for water proofing purposes. So I think its best to enter the panel from the bottom.
I think its better to use 90 sweeps for left or right turn unless sharp turn is needed. for penetration to the brick the LB is required.
to enter the pipe to the box you just need 3/4 PVC male connector with lock nut and deep 1900 box with 3/4 knockouts.
You will need the same connector for the panel to enter from the bottom.
Customer: replied 2 years ago.
One question is still lingering from above. What do you recommend for sealing around the PVC at the point of penetration?
Expert:  Alex replied 2 years ago.
This is what i use for sealing the penetration around the pipe.

http://www.lowes.com/pd_13591-12704-31-601_0__?productId=3127723
Customer: replied 2 years ago.
I finished the job!! I would also like to send you a tip. How does that work? Also, I have a new small question about replacing a "nuisance tripping" combination AFCI breaker.
Expert:  Alex replied 2 years ago.
I'm Glad it worked out. if you want to give me a tip you can do it using bonus feature.
What is the question about the gfci?
Customer: replied 2 years ago.
Actually, it is AFCI. We have a breaker that after heavy rains trips and will not reset until things have dried up a bit. Not every rain causes this, but it happens from time to time. Anyway, the breaker is a Combination AFCI (you can see it in one of the breaker panel pictures I attached recently (see April14 response). The breaker in question is the second from the bottom on the left side of the panel.

I was thinking that since the combination AFCI style will detect 5 amp series arcing and parallel arcing, that maybe I should just change to the branch style which will trip at 75 amperes branch arc faults. As I looked for one at the local store, I see a BR120AF and BR120AFCS. I could not find the difference between these two. Do you know the difference and which I should use?
Expert:  Alex replied 2 years ago.
What is the breaker for? Bedroom ? Are there any outdoor outlets on it?
Customer: replied 2 years ago.
The only "outlet" outdoors on that circuit is the light attached to the "ceiling" above the front porch. Other than that it is for a few receptacles in our front library and lights in the foyer and lights outlets in the guest bedroom.
Expert:  Alex replied 2 years ago.
Replacing the breaker might not solve the problem if device gets wet during the rain. Can you shut the breaker off and go around the house and make a note of what is not working ?
Customer: replied 2 years ago.
I already know what is not working. Are you asking for a summary? It is the circuits I mentioned above which supplies the computer I am on now plus cable modem and router. Other than that, there are no devices drawing power except ceiling fan/light in the guest bedroom and a lamp by the computer and lights in the foyer and front porch.
Customer: replied 2 years ago.
I was just thinking that if I changed to a branch AFCI instead of a combination AFCI that it might be less sensitive to thunderstorms/rain. The other branch AFCI breakers have not had any issues with this over the years.
Expert:  Alex replied 2 years ago.
I'm not concerned about load on the breaker as much as about knowing which device might get wet during rain.
Customer: replied 2 years ago.
I was thinking that initially the device might have been tripped due to lightning (a noted source of nuisance trips for this type of breaker) and then humidity/moisture in the panel might be causing the breaker to not reset (keeps tripping about 5 seconds after reset) until a while later after rains have stopped. ??? The only thing I suspected of getting any kind of moisture was the breaker (other than the light on the front porch which is not directly exposed to rain since it is on a ceiling of the front covered porch.
Expert:  Alex replied 2 years ago.
Well. Then how come only that breaker gets moisture and not others .
Customer: replied 2 years ago.
I don't really think they are getting "wet", I was just thinking that particular breaker may have an issue and is senstive to higher humidity. That was the only thing I could come up with as I thought about it. The whole 75 ampere line arc threshold for trippingthe branch AFCI versus 5 ampere series arcing threshold for the combination AFCI makes the combination AFCI sound much more sensitive. None of the other breakers were combination as you can see in the picture posted on April 14. So, I thought maybe I should just change this problematic one to a branch style like the others. It seemed as though the original electrician must have run out of the branch style breaker and used a combination style he had on hand.
Expert:  Alex replied 2 years ago.
Please give me little time an I will respond.
Customer: replied 2 years ago.
Just a review of my main question for when you have a chance to respond.

Can you think of anything else other than addressing the breaker as the issue?

What is the difference in Eaton BR120AF and BR120AFCS breaker? Which should I buy if I am replacing the breaker?

Also, I don't know where the "bonus feature" is.
Expert:  Alex replied 2 years ago.
1. I guess the first thing will be to replace the breaker but you need to replace it with arc fault since its for bedroom.
2. I will try to get more info on those breakers but according to what I found so far, there is no big difference I just can not find info on trip current yet.
The bonus future will appear after you hit accept button.

That is why I never install panels outside. Nothing but problems.
Expert:  Alex replied 2 years ago.
i just can not seem to find the specifications for those breakers. i will be in supply house this weekend and let me see if i can have more info.

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Alex
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Owner of independent electrical contracting company. Licensed Electrical Contractor in CT.