โJun-05-2013 08:53 AM
โSep-28-2013 05:50 AM
relaxin wrote:
OK in a situation like you describe, which is typical of a farm service, Here in Ontario we would have left in the bonding jumper between the neutral and the ground and installed a ground plate or rods at each panel that does not have a bonding(ground) wire going back to the main distribution point(the pole service in your case)
I would check with your local codes as to how that should be set up, as each jurisdiction can have a different opinion on how it should be done, not saying mine or theirs is more,, or less right.(that lends itself to where liability lies, done right or wrong "according to local codes")
The reasoning is to have any fault current in the grounded/bonded portions of the system (a live wire touching metal casing on say a fixture) carried back to the panel and back into the neutral, failing that, what could potentially occur is if something faults out, the earth your grounding plate or rods are in has resistance(soil type, moisture level, distance from other accepting sources ie transformer ground,) depending on the amount of resistance will determine the flow of power through it, it can be enough to restrict the flow so that the breaker or fuse does not trip or pop and cut off the flow so it stays live until something with less resistance makes contact with it, like say you in a situation where you are touching something else that can accept the flow of current easier than the earth.
a fun experiment you can try at home, drive a rod into the ground out in your yard hook only the hot line to it, plug it in, now make your feet wet, and start form about 100 feet away from the rod, and walk slowly in big 1 yard steps towards the rod, at some point you will feel a tingling sensation which will get stronger the closer you get, your body has less resistance than the earth,,,,, Honestly I don not recommend doing this on purpose,,, but if you must make sure you have someone on a switch to kill the power quickly. this is how people get shocked by downed live lines without even touching them, just an example of resistance in the earth, electricity is lazy and will always take the easiest path,
โSep-28-2013 04:56 AM
sdetweil wrote:relaxin wrote:
all the metal components of an electrical system should be bonded together, not with separate ground rods, all cabinets, ground pins, boxes, fixtures etc etc get "bonded" which all goes back to source, the bond jumper on the neutral then facilitates a safe point of return for fault current, the earth has resistance and is only to be used as a back up encase the neutral in the service fails. the only time you make another Earth connection (with ground rods or plates) is if you run say a U/G triplex out to a distant building like a barn 300 feet away, at that point due to possible resistance in a reduced ground wire and the extra cost of aground conductor it is acceptable to leave the bod jumper on the neutral and install a ground rod set or ground plate. though recently it is strongly recommended for live stock building to have a separate ground back to source and sized appropriately, due to "tingle voltages" and the difficulty in eliminating them.
ok, now you have confused me. (do not bond at subpanels)
I have main service panel on the telephone pole under the meter. earth ground (via ground rod) and neutral are bonded.
then we have three buildings remote from the service panel with their own panels, each with an U/G triplex in plastic conduit.
house - 150ft
shop 1 - 130 ft
shop 2 - 75 ft
no ground wire to any of them from the service panel at the pole.
all three have individual ground rod created earth grounds.
none of these sub panels have neutral/ground bonded. (now)
โSep-28-2013 03:14 AM
โSep-27-2013 03:08 PM
โSep-27-2013 02:46 PM
relaxin wrote:
all the metal components of an electrical system should be bonded together, not with separate ground rods, all cabinets, ground pins, boxes, fixtures etc etc get "bonded" which all goes back to source, the bond jumper on the neutral then facilitates a safe point of return for fault current, the earth has resistance and is only to be used as a back up encase the neutral in the service fails. the only time you make another Earth connection (with ground rods or plates) is if you run say a U/G triplex out to a distant building like a barn 300 feet away, at that point due to possible resistance in a reduced ground wire and the extra cost of aground conductor it is acceptable to leave the bod jumper on the neutral and install a ground rod set or ground plate. though recently it is strongly recommended for live stock building to have a separate ground back to source and sized appropriately, due to "tingle voltages" and the difficulty in eliminating them.
โSep-27-2013 02:26 PM
โSep-27-2013 05:37 AM
thecampingman wrote:
With a safety ground unavailable you should not bond the cabinet to the neutral. Because if something interrupts the neutral between the sub pannel and the earth ground this would energize the cabinet making "taking a look" a dangerous endeavor.
Most codes would require running a separate wire back to earth ground. Then you have to hope whatever interrupted the earth ground didn't also take out the safety ground. Which would probably be the case.
Ideally you should install an earth ground at the sub pannel And have it Megger tested. Megger equipment
I didn't want to drill a hole in the middle of my garage floor and install 12' of ground rod so my sub pannel box is not grounded.
My other sub pannel for my camper is grounded to an earth ground at the box.
โSep-27-2013 05:27 AM
sdetweil wrote:
while not on topic, this incident has made me take a close look at both my subpanels, and both are a mess. ground and neutrals mixed, one enclosure not even grounded.. fun things to fix!
only thing I don't understand, sub panel using plastic conduit,
master has ground/neutral bonded. sub not bonded.
if the conduit had been metal, the sub panel would have inherited the bonding.
what can/am I supposed to do about this?
bond at the sub (no/no)
leave unbonded (maybe?)
โSep-27-2013 04:37 AM
Atom Ant wrote:Likes to tow wrote:it is a normal 220 outlet, so he did something else wrong. Working construction for years doesn't make you an electrician.
A friend of mine wired up his own electrical outlet for his new motor home. He had worked construction for years and just thought it was a normal 220 volt outlet. He destroyed nearly all systems in the coach including the tv. The brand new motorhome went back to the dealer for nearly a month to get it all fixed.
โSep-27-2013 04:20 AM
jdog wrote:you do it youself evey time you plug into 50A service at a campground. There is more what this guy than just plugging into 220.
If you think it's O.K. to plug into a 220 plug then by all means do it. You will find out what happens like the genius OP did!
โSep-27-2013 04:12 AM
Likes to tow wrote:it is a normal 220 outlet, so he did something else wrong. Working construction for years doesn't make you an electrician.
A friend of mine wired up his own electrical outlet for his new motor home. He had worked construction for years and just thought it was a normal 220 volt outlet. He destroyed nearly all systems in the coach including the tv. The brand new motorhome went back to the dealer for nearly a month to get it all fixed.
โSep-27-2013 03:46 AM
โSep-26-2013 11:10 PM
โSep-26-2013 05:16 PM
relaxin wrote:relaxin is right. You should know that lostinaz! A lot of your Montana buds hooked up 220 volt dryers in their rigs by rearranging the two 20A 110 oulets provided.LostinAZ wrote:Jim and Barb wrote:
RGordon is absoulty right! I have been an Industrial Maintenance Supervisor for 10 + years. All it is 220 single phase its only two 110 legs with a ground wire where it ties on a buss bar in the box that is also a tie point for your nuteral on a 110 v circut. The AMP rating is how much draw it it can handel while working 30 AMP is normal for a house.
What isn't being mentioned when we discuss two 110 V legs is they have to be out of phase to create 220V service. My understanding is that the 50 Amp service we hook into at RV Resort/Park pedestals, the two 110V 50 amp legs are not out of phase and therefore 220V is never present inside the RV.
WRONG!!!!
it is both hot legs, it has to be to only have one neutral and in electrical circuitry is referred to as a shared neutral, that in itself only carries the imbalanced load from the 2 hots
example hot #1 is carrying 10 amps, and hot#2 is carrying 15 amps, the neutral only carry's the difference of 5 amps
if you put both hots on one side of the service and lets say you draw on hot#1 35 amps, and hot # 2 you draw another 30 amps, with both hots on the same leg of the service you will have all the current combined on the neutral so 65 amps,,,, dam why is that wire getting so warm
The reason all the RV equipment is 120 volt is so the RV cam function when plugged into with an adapter a 30 amp outlet, the manufacturers realized early on when 50 amp was introduced that it would be a long time before a majority of parks have 50 amp outlets, so most of the time your 220v equipment would never be able to use if you only came across parks with 30 amp