120 & 240 into radio room.

[longhaireddwb]

I just bought to a new to me house. I'm a ham radio operater and want to run both a dedicated 120vac & a 240vac power to my room.
Is it possible to run the 240 to the room and split off of it for my 120 without putting in a subpanel?

 

[PatM]

My laundry room has both 240vac and 120vac coming in from the main breaker panel in another room.
They come in through separate thin-wall conduits.
I would just run the power that way if I wanted to add a linear in my shack
If you have some empty breaker spots in your main panel, do it that way, otherwise just add a subpanel.
Adding another line seems to be the way to go, rather than doing the splitting.
What does your local electric code say?

 

[KeepItSimpleStupid]

Before you do anything, you have to figure out your power requirements because the best your going to be able to do is a 20 Amp 240 volt 4-wire circuit.

So you could have two 20A 120 V circuits, but the 240 V would be shared. So if you were using 5A at 240, you would only have two circuits at 15 A available.

The other thing to remember is that everything could die if the fuse blew. So you could be left in the dark if your lights were on the same circuit.

Sub panels are no big deal You just have to keep the neutrals separate at the sub-panel.

You can also, if you want, use a main breaker panel rated for the same or LARGER than the sub-panel feeder breaker. This main breaker at the sub-panel can then be used as a disconnect. You have to remove the neutral/ground bonding jumper in that sub-panel though.

I think there is good reason to keep the lighting on a totally separate circuit and not in the sub-panel.

You could, if you wanted, put all of "the shack" on a contactor and even use a mushroom switch that would kill power in the entire shack. When I was in high school, that was the system we had. All of the machines were on a contactor/key system. A key was required to arm and the button was used for anybody to dis-arm.

At work it was decided that the panel for the shop, should be in the shop and that was a good idea.

My home bench as four duplex outlets along the front side of the bench that are separately switched plus a light. Then there are outlets (wiremold) that are live all the time. Any serviced equipment gets plugged into an isolated variac.

One upgrade which would be useful is some drop cords with one having a reel. The serviced equipment would probably be run from a drop. A power on indicator would have been really useful for the isolated variac and so would 120/240 capability. Light bulbs and an electronic circuit breaker would round out the system.

 

[longhaireddwb]

I called the city's main electrical guy and asked about putting a Sub-panel in the room for this and he said it would need inspected and a small fee paid but it would be fine to do this. I started thinking that maybe I don't really need to go as far as a sub-panel. Just running to outlets from the main panel might be cheaper.

Now I'm asking questions to the city about putting up a Rohn 25G tower and I'm not getting very straight info. Something about it needing engineered along with the base. This is something that was engineered many years ago by the builder. Why would it need done again unless they just want money.

I'm getting scared I might not be able to have a Ham Shack.

Anyway, Sorry for rambling on about things that don't matter on this forum.

 

[longhaireddwb]

I called the city's main electrical guy and asked about putting a Sub-panel in the room for this and he said it would need inspected and a small fee paid but it would be fine to do this. I started thinking that maybe I don't really need to go as far as a sub-panel. Just running to outlets from the main panel might be cheaper.

Now I'm asking questions to the city about putting up a Rohn 25G tower and I'm not getting very straight info. Something about it needing engineered along with the base. This is something that was engineered many years ago by the builder. Why would it need done again unless they just want money.

I'm getting scared I might not be able to have a Ham Shack.

Anyway, Sorry for rambling on about things that don't matter on this forum.

BTW, The amplifier I run on 240 needs about 15 - 20 Amps itself. Maybe this will make all this impossible? I'm running it on the dryer circuit right now. I just haven't tried to run the dryer at the same time. Don't want to push my luck!

 

[KeepItSimpleStupid]

You have to weigh power requirements, # of circuits and distances first.

The other reasons don't really apply. Sub-panels are easy. You have main-breaker and main-lug type of panels. The important thing to remember that in the sub-panel neutral and ground remain separate. Modern main-lug and main breaker panels have means of doing this, BUT a main-breaker panel may need an optional ground bar kit to do so.

You can read the NEC code onliine for free, you can't print anything from it.

You will have to pay attention to grounding and will probably have to apply for a building permit. Hopefully the foundation info would be supplied by the tower manufacturer. Grounding might require two ground rods and the ground resistance measured. If two are use the ground must be continuous between the two rods.

 

[KeepItSimpleStupid]

BTW, The amplifier I run on 240 needs about 15 - 20 Amps itself. Maybe this will make all this impossible? I'm running it on the dryer circuit right now. I just haven't tried to run the dryer at the same time. Don't want to push my luck!

I believe the NEC would make that illegal. There is another issue is that your usually not allowed to put more than one conductor at the breaker in the panel. Pigtailing is OK.

Just put down your requirements. Any load that is destined to be on for more than 3 hours at a time is known as a continuous load and they are treated slightly different. Space heating is considered a continuous load.

 

[ronsimpson]

What country?
I know NEC and USA wiring.

1) At the main breaker box: use a 220V 30A or 50A breaker. Use wire for 30A or 50A, four conductor wire. Sub-panel: separate ground and neutral, 220V 30A breaker and 15 or 20A 110V breaker.

2) At the main breaker box:
>add 110V 20A breaker for the new 110V service and pull #12 wire.
>add 220V 30A breaker and use four conductor wire (If you don't need the neutral to run the transmitter then could use 3 conductor wire is you mark the wire as 220 by placing black tape over the white wire at each end.) White is neutral but can be marked as hot by using black or red tape over the wire at each end.

 

[longhaireddwb]

that is what I had planed if going the subpanel route. now I'm wondering if it is possible to go with 30 amp 240 and two 15 anp 120 just to have extra and how to go about it. I would prefer the ground on the 240.

 

[ronsimpson]

Question; Is there room in your main panel? Normally I do not add a panel unless there is no free slots in the main panel.

 

[longhaireddwb]

I thought I sent this one but I guess my phone didn't send it.

Do you think it is cost effective to run wires and conduits this far as I will need to go from the garage up to the attic, across the length off the house Approx 70ft) out the exterior wall, down to my room and back in the wall? And making it three instead of two.

This is why I was thinking of the sub panel. Also the sub panel will hopefully have a main to shut off to turn off all my radio equipment. And that brings up another question...

If I go with 240 and two 120 outlets do they all need to be in separate conduits to go across the house and outside and back in? One 2-3 inch conduit would be easier. I'm not sure of the rules on this.

 

[ronsimpson]

Sub panels cost money. Adding a main switch cost money. Not running the two 120V wires will save some money.

All the wires can be in the same conduit.

If you run the two 120V service you could run one cable (black, red, white, green) This type of wire is also used with 3 & 4 way switches.

You need to go to the lumber yard and price out a sub panel. You might find one at the thrift store. If you get a used panel watch out what type of breakers it uses. I have some panels that use strange hard to get breakers ($$$$).

 

[KeepItSimpleStupid]

With conduit, you have to worry about de-rating when you have multiple circuits in it. With NM-B (Romex) or Non-Metalic you have to worry about supporting the cable. If you drill though the joist, you have to worry about structural issues. BTW, it is better to drill in the middle of the joist structurally.

You might be better off using NM-B essentially to a j-box to the inside wall, then conduit on the outside, and conduit possibly all the way to the sub-panel. Remember that all splices must be accessible. You can't cover the j-box up. But, the run doesn't have to be all conduit.

now I'm wondering if it is possible to go with 30 amp 240 and two 15 anp 120 just to have extra and how to go about it. I would prefer the ground on the 240.

Sorry, the grounds have to be for each circuit if you pull separate circuits.

I do hope, this is not considered a "detached structure" for the rules are different.

 

[lebevti]

what is 110V and 220V?? are they line-to-line voltages or line-to-neutral, 3-phase or 1-phase??

Im familiar with 208V/120V (L-L/L-N), so seeing 110 and 220 in this thread confuses me....any info?

 

[KeepItSimpleStupid]

110/220 is probably a left over from 50 years ago. The US uses 120/240 now for single phase residential. It could be described better as split/phase.

The primary of the residential distribution is supplied with a high voltage. The secondary is a 240 CT (Center -tapped) transformer where the CT is connected via a ground rod to the earth and it is also the neutral at one point at the residence.

Both ends of the 240 V CT transformer supply two 120 V circuits as well.

You may hear of 3-wire and 4-wire 240 V circuits. The former consists of Two 120 V circuits 180 deg out of phase relative to the CT and ground. The later 4-wire circuit contains a neutral.

If there happens to be an unbalanced load on the 120 V circuits, the neutral carries the difference. The difference current could be toward ground or away.

208/120 is from a 3-phase Y distribution.

 

[longhaireddwb]

how much derating/amp loss are we talking about when putting all three runs of romex thru about 15ft of conduit?
And thanks to all for helping me with these questions.

sent from phone.

 

[ronsimpson]

In the US 3-phase is not an option in houses. Usually this is real expensive and power must come from a main line. I have a milling machine that needs 3 phase but I don't have the "price of a car" to bring 3-phase to my barn. For the lathe I replaced the motor to get away from 3-phase.

About the ed-rating for conduit; my code book says: for 4 to6 wires derate to 80%, for 7 to 9 wires derate to 70% and for 10-20 wires 50%. By wires a 120V line has 2 wires carrying current.

 

[longhaireddwb]

if its minamal like an amp or threr I won't worry about it as I'm bring more than enough to the room as it is.
I'm guessing the whole ran will be 110 feet for each wire.

 

[longhaireddwb]

so with 2 120 @ 20 amps each and 1 240 @ 30amps were looking at 7 wires so possibly 70% or 30% loss. now is that total or for each circiut?
hopefully my math is right.

 

[longhaireddwb]

oops that the same. sorry for that one.