Wiring an OWB (Shaver)

[Windwalker7]

Here is what I did.

Originally I was going to wire the furnace just like the Shaver instructions recommend. I even ran the 12/3 wire.

I had my pad poured, pipe in the ground and HX in the plenum. Everything hooked up and waiting. I just needed the furnace.

After several delivery dates and delays, it finally arrived.

In the mean time, I decided to just wire up 4 recepticles instead of wiring everything up directly. This way I could just unplug something instead of running to the breaker box. I did wire an outside switch for the fan though.

If I need a place to plug in a Shop Vac or anything else I now have that option.

Since I already had the 12/3 wire in the ground, I just didn't use the red wire.

Anyway, with this set up I run the pump 24/7.

I like to be able to just unplug certain things when needed. The 4 plug GFCI recepticle is located inside the back access door. Its up high on the left side.

 

[jdboy9]

If you don't use a 2P on a multiwire what happens when you do work on the circuit and you don't turn one leg off? Is there not a potential to become a path to ground if something was plugged in or switched on on the still hot leg of the multi?

 

[Wirenut2266]

jd: You are correct. If you kill the black wire per say, red still has small load on it and you don't know it, you open neu. in recp. for repairs, etc.....yup there is great potential for a death......But Legal. I ALWAYS, take cover off panel when killing breakers just to make sure they are not wired as a multiwire branch. But yes, best safety for all, 2p breaker. I always do this when altering circuits, so as to not not overload neu......Great question

 

[Billy_Bob]

If you don't use a 2P on a multiwire what happens when you do work on the circuit and you don't turn one leg off? Is there not a potential to become a path to ground if something was plugged in or switched on on the still hot leg of the multi?

Yes if only one pole is turned off on a multi-wire branch circuit (a circuit with two hots on opposing "legs" of a panel and a shared neutral), and you disconnect and work on the neutral, then the neutral heading toward the equipment end would be hot itself if equipment was turned on (via the other hot wire).

NEC electrical code requires a 2 pole tie bar breaker for multi-wire branch circuits for this reason. With this you must turn off both hots at the same time.

A multi-wire branch circuit must be on opposing "legs" of a 120/240V-neutral electric service. This "balances" the load on the shared white neutral wire if both hot wires are at full capacity or drawing the same amount of electricity.

This works the same way the 3 wires coming into your house electrical service work. Don't need two hots and two neutrals. Just one neutral will work due to the balancing act going on. More...
http://en.wikipedia.org/wiki/Split_phase

 

[jdboy9]

Good glad we can agree on that part of this

 

[mtfallsmikey]

I'm just happy to see some other electricians/tradesmen on here..Work smart, work safe!

 

[urhstry]

Still figuring things out

Well here is what I decided to do. I'm going to run a 12/2 wire to a junction box and tap off constant power to the pumps so they run 24/7. Then i will run a wire to the thermostat to run the fan when it calls for heat. That same 12/2 feed should be able to handle this setup in addition to the outside lights. Anybody see a problem with this?

 

[projectsho89]

Well here is what I decided to do. I'm going to run a 12/2 wire to a junction box and tap off constant power to the pumps so they run 24/7. Then i will run a wire to the thermostat to run the fan when it calls for heat. That same 12/2 feed should be able to handle this setup in addition to the outside lights. Anybody see a problem with this?

Nope. You're only pulling 3 or so amps when everything is on (depends on what wattage lights you use). Unless you are several hundred feet from the breaker panel, you will drop very little voltage through your feeds.

Steve