Wiring for future 220

[mineengineer]

neutral only carries difference of the loads

In the above example if the black wire had 15amps and the red wire had 20 amps then the white neutral would only have 5 amps on it because the two legs are out of phase. If the red and black were in phase then the neutral white would have 35 amps. As long as the red and black are on different legs its okay

[chopnhack]

In the above example if the black wire had 15amps and the red wire had 20 amps then the white neutral would only have 5 amps on it because the two legs are out of phase. If the red and black were in phase then the neutral white would have 35 amps. As long as the red and black are on different legs its okay

Striking out today, I guess I need more sleep... 100% correct mineengineer, my apologies.

I still stand behind taking extra care with multiwire branch circuits, you too could be sleepy when pulling and end up mislabeling wires. Put them in the wrong phase and end up with a fried wire! ;-)

[mpc]

Question for that diagram showing a shared neutral and assuming the hot leads are in fact coming from opposing phases. If that is a safe and NEC-legal configuration, is there any special marking that has to be done inside the circuit breaker box? If not, what's the clue to future electricians, or DIY homeowners, that the red and black MUST be on separate phases? I can see somebody swapping a standard circuit breaker for a double-breaker (to add circuits) moving a few "hot" wires around and unknowingly ending up with a shared neutral on the same phase.

Also, if that shared neutral has any extra resistance - especially at the end near the circuit breaker box - a high-amp load on one side will experience a voltage loss but what will the apparent voltage be on the other phase? Any chance it could see a voltage rise? I'm thinking of situations I've read about where a refrigerator compressor turning ON caused some lights to brighten so I'm guessing they were on the other phase of a multiwire circuit.

mpc

[greenacres2]

Great--that makes some sense, and helps me understand circuits a little better. Now for the question i was really searching for when i stumbled into that...

I'd like to have a 240 volt circuit and convert the table saw, RAS and jointer. I would however, like to have two different locations to plug into--one between the overhead doors on the north wall, one on the west wall. If i were only going to use one of these machines at a time--could i attach 2 receps to the circuit? Or must each recep have a dedicated circuit?

I'm keeping the DC at 120 volts, it doesn't lug at start-up and it's on its own circuit anyway.

The RAS and TS both really bog at start-up, dimming the lights most of the time. The jointer is a "while i'm doing it" kind of thing.

Thanks,
earl

[chopnhack]

To MPC's question: A very valid concern. Most residential wiring that is done with romex follows a uniform color scheme - that is to say that 14/3 and 12/3 has a white, red and black plus ground, 14/2 and 12/2 white, black and ground (I believe that this also is correct in other gauges - IIRC 10/3 is the same) If one would see a red wire in this setting, one would correctly assume that there is a xx gauge/3 bundle in use. So long as there are no other types of wiring coming into the can like thhn, etc. Outside of that you can look at the entry point into the can of each group to see how things are being run. Also, if you run a bunch of wires together in conduit from different circuits that are multiwire branch circuits, then you have to zip tie the groups of wires that belong together. There are some tells, but you are right, people who aren't aware of these things can get into some trouble with mbc's.

NEC legal from what I recall, the only thing that might be omitted from the drawing or not clear enough is the tie bar on the breakers - there is some verbiage about simultaneous disconnecting of all non grounded conductors in these type of circuits for safety sake.

On topic - Earl, wouldn't you want to run your dc while you operate the other equipment? You would want to run a 120 circuit and a separate 220 circuit in some form of conduit. If you have attic access you can do two separate drops - one to each of your locations, north and west walls. If no attic access, run conduit to your first drop, put in a T conduit body, drop down for your first outlet group (120 or 220) then continue the other wiring to the last drop. HTH

[greenacres2]

On topic - Earl, wouldn't you want to run your dc while you operate the other equipment? You would want to run a 120 circuit and a separate 220 circuit in some form of conduit. If you have attic access you can do two separate drops - one to each of your locations, north and west walls. If no attic access, run conduit to your first drop, put in a T conduit body, drop down for your first outlet group (120 or 220) then continue the other wiring to the last drop. HTH

Thanks Chop--This would be a lot easier if i ever get around to learning Sketchup!!

The DC (the HF "2.0 HP" version) is on a 120 circuit with only an overhead door opener and is fine as it is since i power it up first. The amperage draw on the system when i start a tool, even though on a separate circuit, is the issue i'd like to help. Stud walls only, so i've got access and the top plate is at 10'. Building is detached with a 100 amp sub-panel fed from the house. Panel is on the west wall.

I'd like to come across 24" with 12-3 and drop to a 240 recep (gfci there if not at the box) between the overhead doors on the north wall, back up over 12' to the east wall then 12' and drop a second 240 recep and mark both covers as to voltage AND not to use together. If that's doable, i can plug the RAS, TS and jointer in where i normally use them. If i can only do one drop on the circuit, it'll be on the north wall and i'll make up a 15' to 20' cord and do what i'm doing now--but i'd prefer not to have cords across the floor.

So the question--can i do two drops on a 240 circuit?

earl

[chopnhack]

Ok, if we are running strictly 220v, you will only need 12/2 - no neutral needed in a 220 circuit, just two hots, one from each side of the tap and a ground. As for how many outlets, I don't know that there is a hard and fast rule, maybe an NEC hound can come by and illuminate us, but a rule of thumb I have heard is no more than 6 outlets per breaker. I always thought this to be a fair allowance in a residence, but for a shop setting.... I would say no more than three and only if you understand which three are on one breaker. One tool alone can use up most of the capacity.

In your situation, go 12/2 to your two drops with a 6-20r duplex and your good to go. 3/4" spade to drill holes through top plates, "hog" staples to fasten NM cable to center of wide face of stud.


from: http://www.mrsupply.com/leviton-1646...FQ83nAodkVsArA

I don't believe you will need GFCI - there was some verbiage in the NEC that said if the receptacle was a dedicated outlet then no GFCI was required, i.e. a 14-30R - there is no way you could mistake it and plug in a standard 5-15P or 5-20p (120v device plugs) into one of these. I use the same reasoning on with the 6-20R's as you can not physically insert a 120v plug into one. I guess the intent was to protect the consumer who has access to corded 120v devices and may encounter a shock hazard, but was less concerned? with the risk of 220v devices as most are either hardwired or on dedicated plugs, I dont know for sure.

[greenacres2]

Thanks!! Just a pair of 240 outlets in convenient locations--single outlets at both locations. My plan is to put them on the same studs as existing 120's and there's plenty of room in the plate holes. The 120 circuits are run on 14-2 wire so the yellow jacket on the 12-2 with red tape at both ends should give a visual clue as well.

Now i've got direction, it's down to money at this point which isn't too bad--and with racing season just ahead i'll have some spare change from the tracks.

earl

[chopnhack]

They do make single outlet instead of duplex, but I figure even if the tools aren't running simultaneously, its convenient for leaving them plugged in. If the existing 14/2 is stapled and you dont feel like prying them out, you can zip tie the new run to the old ones - check with local codes, but has never been an issue here. If you source it right you should be under a c-note :-)

[cabinetman]

A word of caution. The advice here is free, so take that FWIW. Those that offer advice may or may not be an electrician, so with that in mind, consulting a real electrician (face to face) will provide the electrician the opportunity to evaluate what's on the premises and the conditions that exist.

.

[greenacres2]

A word of caution. The advice here is free, so take that FWIW. Those that offer advice may or may not be an electrician, so with that in mind, consulting a real electrician (face to face) will provide the electrician the opportunity to evaluate what's on the premises and the conditions that exist.

.

Message received and understood Sir!!

Actually our office was built as a home in about 1866, converted to office space in the mid-1950's and we have 17 employees in this location. So...we have an independent electrician in about once a month chasing Gremlins. Jerry will do the final hook-up in exchange for NHRA tickets to the Indianapolis race, i'm just trying to figure out if i can afford it.

I think it's more do-able than i thought. I can buy 250' of 12-2 for $60 delivered and then resell at least 150' (or i can go to the box store and buy 100' for $60 and resell nothing), breaker is $9, 2 boxes for $5, so it looks like the biggest expense will be 6-20 plugs for the tools. I did speak with Jerry last spring and adding a single circuit to an existing box did not need a permit here--that helps.

Thanks to all for the info--i'll keep you posted.

earl

[chopnhack]

FYI: I am not an electrician. I have run spools of wiring in different settings, home, shop and condo so I am familiar with some different wiring scenarios but I am not licensed and so C-Man's advice is certainly worthy to listen to.

As for the expensive 6-20 plugs?

check ebay, fruit ridge tools sells them on their ebay site sometimes for as little as $5 a piece otherwise, see here http://www.fruitridgetools.com/store...FQSpnQodAiEA_Q

Where did you get a price on 250' of 12/2 for $60 delivered? Share please ;-)

[greenacres2]

Where did you get a price on 250' of 12/2 for $60 delivered? Share please ;-)

Short answer--apparently i made it up!! Went back to ebay, found 100' at $54 BIN, but not even close on 250'.

There is a guy with 50' sections of 12-2 at 17.99 shipped (http://www.ebay.com/itm/160970963349...84.m1438.l2649). Wire is from CME Wire and Cable out of Suwanee, GA. Southwire is the most common brand (Lowe's at 70.90 for 250' here, would be $67 with the 5% off--maybe that is what i was thinking) and they are in Carrollton, GA.

So, a pair of 50' from ebay for $36 or 100' from Lowes at $48/$46 net?? I'll get it figured out.

[greenacres2]

In and done--at least the circuit and the RAS. Receps, breaker and plugs were sourced through Fruitridge's ebay link--all Leviton stuff, 12-2 wire from another e-bay. Boxes/covers local. Came in a tick under $100 in materials, supervision complementary (we'll have them over for dinner soon--which we do anyway!!).

Since the plugs were cheap ($28 for 10 Leviton armored) I did take advantage of the Ace 20% off sale and buy 20' of 12/3 SJOW and made an extension cord since the power cords are all 6' and i cant stay that close to the wall. That short should result in virtually no resistance drop. Had originally planned to cut up a 50' that rarely gets used, but decided to save it intact.

Once my feet warm up i'll convert the bandsaw, planer and table saw--should be easy. Even with oversight, the connection and power-up came with healthy fear bordering on sheer terror--especially sticking the multimeter probes into the outlets!! Thanks for the help, support and input--along with being concerned enough to offer warnings and cautions!!

earl

[woodturner]

(Lowe's at 70.90 for 250' here, would be $67 with the 5% off--maybe that is what i was thinking)

FWIW, different HD stores in this area have different prices for wire - one store is half the price on the 250' rolls, compared to two others.

Lowes reprices commodity items like lumber and wire daily, so they are usually higher than HD unless there has been a sudden price drop in the commodity price.