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Help Please quick question on electricity
- Thread starter Sluicebox
- Start date
queeq, your 4/0 aluminum is rated quite a bit lower than 250a. The insulation of the wire (there are several types) is what determines the actual rating. The highest-rated insulation is good for 205 amps, and the lowest is 150. The length of the run can drop the current capacity further, particularly with the higher resistance of aluminum conductors vs copper.
yea i was going off of bad memories, im sure you are correct.
no clue what the insulation was other than it being rated for direct burial. house was built in the late 70's, did they even have the good thin insulation back then?
the transformer is back some 50 feet in the easement. trenching a new one would be fairly easy assuming the conduit under the pool deck is in decent shape.
THHN, the highest rated insulation now, was brand new in the late '70s and probably not available as anything other than as a single conductor meant for installation in conduit. During that era, direct burial multi-conductor cable was probably TW, and would be rated for right at 150 amps.
lol damn... you've crushed my dreams of a serious garage sub panel.
I got my contactors in the mail today. Packard C240A . They are 2 pole single throw. Now there are 4 blade terminals under each heavy screw lug and 2 on each side. I know the ones on the side are for the 24v control relay. The ones under the shttps://www.johnstonesupply.com/storefront/product-view.ep?pID=L45-038crew lugs, can those be used to power auxiliary 120v circuits? Like in this instance an inline fan that would come on when the contactor closes and powers the lights? Seems like you would just be pulling power from the load side only one pole and 120v neutral would tie in with other neutrals. This would go to fan powering fan when coil is energized. This is on a 30A circuit though, but still one half of that is = to 120v isn't it?
https://www.johnstonesupply.com/storefront/product-view.ep?pID=L45-038 sorry there is the link
not sure if i understand you.
you need a contactor for each circuit breaker, not for each piece of powered equipment.
if you were to take power from the 2 pole contactor running your lighting... you are taking power from one pole of your lighting circuit. when that one pole exceedes 30 amps you trip your breaker.
just use another contactor ganged onto what ever circuit is powering your lighting contactor coil.
you can use a 2 pole if you like... you only need onepole switched though.
you bought single throw switches. you cannot switch both rooms, and will need separate contactors for each room with separate timers probably.
you need a contactor for each circuit breaker, not for each piece of powered equipment.
if you were to take power from the 2 pole contactor running your lighting... you are taking power from one pole of your lighting circuit. when that one pole exceedes 30 amps you trip your breaker.
just use another contactor ganged onto what ever circuit is powering your lighting contactor coil.
you can use a 2 pole if you like... you only need onepole switched though.
you bought single throw switches. you cannot switch both rooms, and will need separate contactors for each room with separate timers probably.
K thanks, I was just unsure what those blade terminals were for. I won't be using them for my application, just the ones on the sides running the coil.
Run so far is 60A breaker at main service panel out to sub via 6-3 copper at sub have 2x 30amp dp breakers, out to 2x cans via 2x10-3 these cans have the contactors in them one for ea room,out of those via 2x10-3 to 2x small subs containing ? Stuck there figured on putting in 15A double pole breakers here to run at 240v there would be 2 of these breakers in each room. Could add 15A single pole here to run the fan for air cooled lights. Then fan would come on and off with lights.
Additional load on this circuit would be 2x 15A 120v breakers for 12A Air conditioners, one in ea room, and 2x 15A 120v breakers for wall fans and environmental controllers one in each room. These breakers are in the first sub running off the 60A circuit and not controlled by contactor.
Controlling relay is 24v and will run both rooms. Hope that clears it up.
I was just trying to see if I could eliminate that 15A single pole running the fan for air cooled lights by coming off that contactor. I guess however I would have to stay at 30A all the way to fan if I did that.
Please hang in there with me on this, don't get frustrated. I'm almost done with it.
Lastly can all this run at once or do I still have to flip the rooms and stay at 12/12? Remember that is 60 amp at main, 8x1kw lights@ 4.5A ea, 2x12A air cond, wall fans are like 1A ea or so 8 of these. My math shows that I am over capacity on the 60A.
I can make room in main service panel to run another breaker out to another small sub to run air cond and fans, would be pretty easy to do at this point.
Run so far is 60A breaker at main service panel out to sub via 6-3 copper at sub have 2x 30amp dp breakers, out to 2x cans via 2x10-3 these cans have the contactors in them one for ea room,out of those via 2x10-3 to 2x small subs containing ? Stuck there figured on putting in 15A double pole breakers here to run at 240v there would be 2 of these breakers in each room. Could add 15A single pole here to run the fan for air cooled lights. Then fan would come on and off with lights.
Additional load on this circuit would be 2x 15A 120v breakers for 12A Air conditioners, one in ea room, and 2x 15A 120v breakers for wall fans and environmental controllers one in each room. These breakers are in the first sub running off the 60A circuit and not controlled by contactor.
Controlling relay is 24v and will run both rooms. Hope that clears it up.
I was just trying to see if I could eliminate that 15A single pole running the fan for air cooled lights by coming off that contactor. I guess however I would have to stay at 30A all the way to fan if I did that.
Please hang in there with me on this, don't get frustrated. I'm almost done with it.
Lastly can all this run at once or do I still have to flip the rooms and stay at 12/12? Remember that is 60 amp at main, 8x1kw lights@ 4.5A ea, 2x12A air cond, wall fans are like 1A ea or so 8 of these. My math shows that I am over capacity on the 60A.
I can make room in main service panel to run another breaker out to another small sub to run air cond and fans, would be pretty easy to do at this point.
ill read this later on.
sorry for the delay...
if only one room is to operate at a time... then i dont see any grievous issues with your two proposed sub panels.
the only thing i don't like is your lack of any safety interlocking. there is nothing to prevent or lockout the other room from energizing whilst the other is already on. a DPDT contactor would have acted as this interlocking mechanism, at least with respect to the main HID lighting load. but it seems now you are proposing two timers and two relays... there is nothing but the timers to stop them both trying to energize both rooms.
all that being said... you have the MCB and sub panel breakers there to fall back on provided everything is installed correctly.
i urge you to double check your wire ampacities, as i did not bother googling them to verify your choices.
so no, you should not try and run each room at once... if you wish to run one big room, then redesign for a single sub panel. i dont understand how you came up with additional ampacity on these panels however. it seems to me that they will be full pretty much 100% with just the lighting and ac loads.
each rooms sub panel is 30a correct?
as far as i can tell... you are proposing 4kw in lighting, and 12 amps in ac load... that right there is basically full.
17 amps lighting and 12 amps for your ac? where is the space for your other stuff?
these loads are not intermittent mind you. you cannot assume some small demand factors so you have 0 wiggle room.
You are beyond zero wiggle room. The ballasts have parasitic losses just for their own operation, usually around an additional 10% over and above the light wattage. The compressor motor in the air conditioner can easily pull 300% current during startup - it's a relatively quick surge, but if you are running at maximum, it's enough to either trip the breaker or have the HID lamps drop off line from the voltage sag.
While we are at it, you need to be aware of the 80% rule. You are only allowed to use 80% of the breaker rating for continuous loads, which are defined as any load longer than 3 hours in duration. So, on a sub-panel fed with a 30a breaker, you are limited to 24 amps of continuous load. Short duration loads can bump up to the full rating of the breaker.
While we are at it, you need to be aware of the 80% rule. You are only allowed to use 80% of the breaker rating for continuous loads, which are defined as any load longer than 3 hours in duration. So, on a sub-panel fed with a 30a breaker, you are limited to 24 amps of continuous load. Short duration loads can bump up to the full rating of the breaker.
will this timer work to control a dpdt contactor?
http://www.amazon.com/dp/B00DVLW224?psc=1
http://www.automationdirect.com/adc...n-Style,_40A_(AD-PR40_Series)/AD-PR40-2C-120A
There you go will that time switch flip this contactor? If I have 2x 15A 2pole 240 volt breakers in 40amp sub panel out to two recepts with ballasts plugged in. Will this work to flip 8 lights using 4 ballasts. There would be two of those dpdt contactors, only flipping the hots coming from ballasts to lamps, neutrals would be tied together bypassing contactor as would the grounds. I think this will work. I ditched the idea of Air conditioning for now. Thanks.
http://www.amazon.com/dp/B00DVLW224?psc=1
http://www.automationdirect.com/adc...n-Style,_40A_(AD-PR40_Series)/AD-PR40-2C-120A
There you go will that time switch flip this contactor? If I have 2x 15A 2pole 240 volt breakers in 40amp sub panel out to two recepts with ballasts plugged in. Will this work to flip 8 lights using 4 ballasts. There would be two of those dpdt contactors, only flipping the hots coming from ballasts to lamps, neutrals would be tied together bypassing contactor as would the grounds. I think this will work. I ditched the idea of Air conditioning for now. Thanks.
I already have one of these that I am currently using, would be nice if I could run the contactors with it and save some money.
http://www.amazon.com/gp/product/B00004W4XI?keywords=wh40 timer&qid=1447583531&ref_=sr_1_1&sr=8-1
I could order these contactors instead, I think they will work with the 240v timer linked in this same post.http://www.automationdirect.com/adc...n-Style,_40A_(AD-PR40_Series)/AD-PR40-2C-240A
http://www.amazon.com/gp/product/B00004W4XI?keywords=wh40 timer&qid=1447583531&ref_=sr_1_1&sr=8-1
I could order these contactors instead, I think they will work with the 240v timer linked in this same post.http://www.automationdirect.com/adc...n-Style,_40A_(AD-PR40_Series)/AD-PR40-2C-240A
It's my understanding that the neutral between the ballast and the lamp would be the neutral leg on a 120v circuit. Rather than becoming a 120v hot leg like in 240v. Therefore I should be able to bypass contactors with neuts and grounds just run the hots through the contactors. Would I have to leave a 240v breaker in the sub to run the timer? Currently there is a 30 amp in the sub going out to that 40 amp 240v 10000w timer then out to two recepts running 4 ballasts at 240v. That timer would just be running the coils on the two contactors. If this is a waste of juice let me know please. I haven't ordered the contactors yet. Those are avail with 12,24,120, and 240v coils. If you know of a better timer to work with these contactors let me know. Ideally I would like one with 4 zones or channels for a later build. But I would get by with just enough to flip the 2 rooms 12/12 for now.
Thanks again.
Thanks again.
http://www.automationdirect.com/static/specs/pr40powerrelays.pdf or this link may be better as it is not a download (pdf) 2nd link is just the web page.
http://www.automationdirect.com/adc...n-Style,_40A_(AD-PR40_Series)/AD-PR40-2C-120A
The only question that I have left on this is... Does the coil on this contactor have a designated polarity? Meaning will the neutral have to go to a certain side and the hot on the other. I just didn't want to have reversed polarity at the coil. I know on the 24v coil model there is no designated polarity, but was unsure on this one, I wouldn't think it would matter but just wanted to ask the smart bench.
I wound up just running off that 40A circuit out to a sub then 2x15A dp breakers wired 240v out to 2 recepts. The 4 ballasts plug into the recepts and are powered 24/7. The 4 lamp cords go out to two dpdt contactors controlled by an intermatic mechanical time switch that gets it's power from a different circuit. 4 lamp cords to room A and 4 lamp cords to room B. In addition at the sub there is a 15A circuit for each room. Load on those circuits though is only 5A per room for fans.
Edit: These are magnetic ballasts, future upgrade will be switches for the lamp wires. I need to look into whether or not that would hurt anything to have the ballast on with the lamp switched off. That would only be necessary for maintenance on the room, or early spread before flip. If I had to I could turn off at breakers, Intermatic time switch would still keep track of time.
Hope that all sounds right, anyway thanks so much for your help everybody. Be well and Safe.
R.
http://www.automationdirect.com/adc...n-Style,_40A_(AD-PR40_Series)/AD-PR40-2C-120A
The only question that I have left on this is... Does the coil on this contactor have a designated polarity? Meaning will the neutral have to go to a certain side and the hot on the other. I just didn't want to have reversed polarity at the coil. I know on the 24v coil model there is no designated polarity, but was unsure on this one, I wouldn't think it would matter but just wanted to ask the smart bench.
I wound up just running off that 40A circuit out to a sub then 2x15A dp breakers wired 240v out to 2 recepts. The 4 ballasts plug into the recepts and are powered 24/7. The 4 lamp cords go out to two dpdt contactors controlled by an intermatic mechanical time switch that gets it's power from a different circuit. 4 lamp cords to room A and 4 lamp cords to room B. In addition at the sub there is a 15A circuit for each room. Load on those circuits though is only 5A per room for fans.
Edit: These are magnetic ballasts, future upgrade will be switches for the lamp wires. I need to look into whether or not that would hurt anything to have the ballast on with the lamp switched off. That would only be necessary for maintenance on the room, or early spread before flip. If I had to I could turn off at breakers, Intermatic time switch would still keep track of time.
Hope that all sounds right, anyway thanks so much for your help everybody. Be well and Safe.
R.
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I ran 90 amps off a 100 amp service, it is cold here and I figured go for it. The breaker box would get very warm but not hot enough to burn me.
Equipment started failing, even the fans were having problems.
After shutting down for a year and starting over I checked the voltage drops in the old system.
Some circuits were dropping down to 90 volts under full load, causing heat buildup and electrical failures in ballasts (fluorescent and HID), LEDs, and fans.
I use 65 amps now and the voltage maintains 110 volts at the outlets under this load. I learned not to run equipment right at the ragged edge of too much, the stress causes damage right from the start.
Equipment started failing, even the fans were having problems.
After shutting down for a year and starting over I checked the voltage drops in the old system.
Some circuits were dropping down to 90 volts under full load, causing heat buildup and electrical failures in ballasts (fluorescent and HID), LEDs, and fans.
I use 65 amps now and the voltage maintains 110 volts at the outlets under this load. I learned not to run equipment right at the ragged edge of too much, the stress causes damage right from the start.
