| Author |
Message |
Richsale
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 28, 2005 - 7:13 pm: | |
I want to setup a spot at my home for my MH. I have a 50/30 amp box and need to know what size wire I need to use as the incoming power source. I have a 2/3 with ground, is this wire to big? |
Jack Conrad (Jackconrad)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 28, 2005 - 7:23 pm: | |
10/2 with ground is usually used for 30 AMP (120 volt). Larger is OK, EXCEPT it might to difficult to connect the large wire to the receptacle. 50 amp is 240 volt and requires 6/3 with ground. As above, larger wire can be used but is difficult to attach to the receptacle. Ground wire is usually 1 gauge smaller that hot and neutral legs. Hope this helps, Jack |
Kyle Brandt (Kyle4501)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 28, 2005 - 8:02 pm: | |
I'm no electrishun, but as an engineer, I think I know everything worth knowing :^) What I did for my dad was run 60 amp (220v) to a remote panel located where he needed the outlets. Then I put in the following outlets: 20A(110v) - 30A(110v) - 20A(220v) - 30A(220v) and 50A(220v). Each has its own breaker and usually only one will be used at a time. We now have a power source for any 'toy' we may need to use while working on his RV or my bus. If we try to pull too many amps, the 60A breaker will trip & keep everything safe.
It has worked out nicely for us.
You could use that large wire to feed a subpanel & not need to buy much wire to feed the outlets. You need not put in all the outlets that I did, but my 'toys' required that many. You can always add as required later since it's all right there.
If you are not comfortable doing this yourself, get experienced help, it will save money in the long run.
kyle4501 |
Brian Brown (Blue_velvet)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 28, 2005 - 11:26 pm: | |
Good advice, guys.
Also, don't forget, if you wire a subpanel (like Kyle has done) you must unbond the ground to neutral with a separate grounding bar AND remove the box bonding screw.
In other words, you can't wire it like the main where grounds and neutrals are tied to the same bus.
Before you button it up, check your grounds with a continuity tester to insure it's only bonded at the main.
bb |
Steven D. Braud (Steve77amg)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 29, 2005 - 6:00 am: | |
Hey Brian, Could you explain with some more detail about ubonding a ground? I would like to do something like Kyle did for my bus. I have a 240v line going to my wellhouse and would like to run it another 75 ft to where the bus is parked. Thanks for any info you can provide. |
Brian Brown (Blue_velvet)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 29, 2005 - 11:17 am: | |
Sure, Steven. Your typical main breaker box has a grounding bar that all of the neutrals and grounds get tied to, essentially bonding the two together at that point. They then branch out feed individual circuits "downstream". Upstream of your main box, the big wires from the service come in, the three wires (2 hot legs and 1 neutral) from the power co. go to the pole, and the ground wire gets tied down to a suitable ground, like a buried rod or a metal water line.
Per code, and for safety sake, a subpanel must NOT bond the two together again (creating a possible neutral/ground loop), but the neutral and ground must be distinct wires all the way back to the main.
This is accomplished by using a separate grounding bar, either provided with the box or purchased separately to attach to the box. All of the neutrals are now tied to the neutral bus bar, and all of the grounds to the separate grounding bar that also grounds the metal frame of the box. There's also a box bonding screw in the panel box that should be removed, to remove continuity between the metal panel/grounds and the neutral bus bar.
Also, make sure that your existing 240v service has four wires (two hots, one neutral, one ground). If you're missing the ground wire, make a suitable ground connection (typically a grounding rod driven deep into the earth) near the new subpanel.
If you're not at all confident in doing this work, please hire an electrician to do it for you. Your life, and those in and around your bus, might depend on it.
HTH,
bb |
gg04
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 30, 2005 - 5:34 pm: | |
But if they are both tied at the main (making both wires the same as one) how will not tying them together upstream change any thing???? Still any check will go back to the tied connection?? You would have to add a seperate ground to do this ...... Right ?? RV code calls for not tying together on the RV..with frame ground on generator...to keep walls from going hot from neutral loop. Every rv park receptical I have ever seen has neutral ground tied together... GG04 |
Kyle Brandt (Kyle4501)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 30, 2005 - 6:36 pm: | |
If the ground to neutral bond failed at the main panel, the current using this bond will travel to the subpanel to find ground. Usually the subpanel is wired with smaller wires than the main, & the current path is longer. The resulting overcurrent could start a fire. Hence the rule.
In the case of a RV, that fire could happen inside your coach if the RV's neutral & ground are bonded.
I have also noticed if the RV's neutral & ground are bonded this will cause sensitive GFCIs to trip.
The little 3-light outlet checker cannot tell the difference if the neutral & ground are tied together properly in the main panel, or improperly at the outlet.
FWIW
kyle4501 |
Richard (Richsale)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 30, 2005 - 6:44 pm: | |
Can we get back to the original question (I want to setup a spot at my home for my MH. I have a 50/30 amp box and need to know what size wire I need to use as the incoming power source. I have a 2/3 with ground, is this wire to big?)
Jack Conrad gave me a logical answer. My question know is:
Will the 6/3 wire be big enough if both receptacle (50 and 30)are being used at the same time and the length of wire is 75'? |
Jack Conrad (Jackconrad)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 30, 2005 - 7:03 pm: | |
6-3 wire is rated to carry 50 amps in each hot lead (the red and the black wires). If you are also running a 30 amp circuit simultaneously from this set of wires, you will be using the red OR black and the white for the 30 amp (120 volt). This means those wires that you are using for the 30 amp circuit are now conducting a total of 80 amps. IF both circuits are operating at max load. Not Good! If the total load is limited to 50 amps, you will be OK. |
Kyle Brandt (Kyle4501)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 30, 2005 - 7:33 pm: | |
Richard,
It is hard to keep the answer simple & cover the bases.
2/3 wire with insulation type:
THHN (dry locations) is rated for 120amps.
UF (moisture resistant) = 95amps.
3/3 wire with:
THHN (dry locations) is rated for 105amps.
UF (moisture resistant) = 80amps.
6/3 wire with:
THHN (dry locations) is rated for 70amps.
UF (moisture resistant) = 55amps.
(the above was taken from Mark's Standard Hhandbook for Mechanical Engineers, 8th ed.)
Why I suggested a subpanel:
If you have only one breaker at the panel feeding two outlets, you must fuse it to protect the lower amp outlet.
If you use the right sub panel:
- you can mount the outlets right beside/ under it,
- it will have big enough lugs to use the 2/3,
- you can install a 80amp breaker in the main panel,
- You can protect each outlet with the proper breaker,
- you will have a disconnect right there at the MH.
I hope this helps,
kyle4501 |
Richard (Richsale)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, October 01, 2005 - 8:57 am: | |
Ok here is what I have:
Main box (A) has a 125 breaker. 75 feet away I have a box (B) with a 50 amp breaker with a 50 amp outlet and a 30 amp breaker with a 30 amp outlet. This box comes pre-wired so that both outlets can be used simultaneously.
What would be the best size wire to connect box (A) to box (B) |
Kyle Brandt (Kyle4501)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, October 01, 2005 - 10:21 am: | |
If the insulation on the 2/3 is UF;
Since you have the 2/3 with ground, verify that it will fit the lugs in box (B), if so, you can use the 2/3. You will need to connect it to a breaker in box (A) sized between 80 & 95 amps.
If the 2/3 is too big for box (B), 3/3 with ground should work. Connect it to a 80 amp breaker in box (A).
The smaller wire sizes will not provide enough capacity to use both outlets at once.
Be sure to heed Brian Brown's good advice too. |
Richard (Richsale)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, October 01, 2005 - 10:04 pm: | |
Thanks guys. Wired up the box today and everything working great. #2 wire fits just fine. Thanks for everyones help. |