Job Trailer nightmare

[bullheimer]

i guess there is no way this thing is ever going to pass code so i just want to make sure i don't kill anybody. i only pulled a permit for this remodel job, i did not know there was going to be a trailer there until just the other day, at a pre construction meeting when the Port guy asks me to hook up this trailer they got for the longshoremen to take breaks in while the old place is under construction.

the trailer has an overhead service mast! the old building is being fed from overhead 3 wire. they own the wires and use the power companies sizes, i guess, as it sure isnt 4/0. the building was built in the 60's hence the 3 wire, because this is fed from a breaker in a disconnect some 150 feet away! i could find NO ground rod and assume its under the brick or slab.

i said i would do it so i did it: i hooked up 3 wire aerial to this trailers mast. i did not notice the green ground wire in the mast till i bought the wire, but there isn't anywhere to hook it up to, on the pole anyway! the 3 wire overhead obviously doesnt have one, the old building, obviously, has the neutral and ground bonded together, so i think it would therefor be pointless to run a ground wire to the buildings panel.

With my circuit tester, ALL the outlets in the trailer said they were grounded!!! i can't explain this. other than pouring rain and the tongue of the trailer was on the wet ground. i took voltage readings from the frame to the ground and zero. i felt them both, nothing shocking. And, i got 120V from the hots to the isolated (as far as i could tell) ground bar, as well as 120V from hots to neutral.

so i figured, since they must be bonded somewhere, somehow, and i did not want the green wire just hanging out of the weather head, i connected the green ground wire into the butt splice with the neutral. everything works fine.

i am worried that i need a ground rod and should separate the ground and neutral. this will never pass because there is basically no way i can find a ground anywhere, and the main breaker is at least 100 feet physically and 160 feet electrically from the trailer.

can anybody tell me what to do and why. i read a 4 page post on this here and got two differing sides squaring off. and like i started this off, i dont care about the code, i just want this trailer to be safe. (right in front of it in the rain are extention cords and more extension cords plugged into octopusses NOT plugged into a gfi recept. this building has NO gfi outlets outside.) i just did this today and need your opinion. THANKS. my worry is maybe the trailer was grounded from the rain, and as soon as it dries out (in june) there may be a shock hazard.

ps, there are NO sleeping quarters and NO cooking equipment. only appliance is a hvac unit. no bathrooms either.

 

[Cow]

If you fed it with 3 wire, you'd treat it just like a service.

Bond the neutral/ground IN THE PANEL(not at the weatherhead) and install a grounding electrode system.

 

[kwired]

If you fed it with 3 wire, you'd treat it just like a service.

Bond the neutral/ground IN THE PANEL(not at the weatherhead) and install a grounding electrode system.

I agree, if you go back a couple code cycles where 3 wire feeder would have been permissible, you still did all the same things you did for a typical service - in most cases. If there are other potential grounded paths for neutral current to flow then you still had a problem and needed separate grounded and equipment ground conductors anyway.

I think bottom line, this is not reusing an existing 3 wire feeder. This is a different structure that was not in place before, and had no existing feeder before therefore it does not qualify for the exception to reuse an existing 3 wire feeder. If you had a secondary structure supplied with a 3 wire feeder that was code compliant when it was installed and were changing the main panelboard out, that would be a case where you could reuse an existing 3 wire feeder to a separate building.

If you are only concerned with it being "safe" consider the reasons why NEC decided to require a 4 wire feeder. I think objectionable voltage or current on equipment grounding conductors is likely the number one reason.

 

[bullheimer]

i think you are both right.

this came to me about 4 am: there is a huge drain almost under this trailer. it has metal 2x3' grates all across it for about 400 yards. (this whole area is blacktop). the grates are on a steel lip. i think the whole ditch, about four feet deep, might be made out of metal. i am going to get a #4 automotive battery cable long enough to reach from the frame of the trailer to a self tapping bolt to the hopefully metal sides, or to the lip of the edge. that should qualify as a grounding electrode to anybody. then remove and cap off the ground at the weatherhead.

one side note about your (kwired) last sentence, is that if it were that much of a safety hazard, they wouldnt allow for 'grandfathered in' 3 wire. but i have to admit there must be valid reasons out there, or it wouldn't be in the code. i am wondering if the AHJ will require them to refeed the remodeled building thru the air, when we get done. i know i will get nailed for this trailer not having a D/C w/in 30' when they inspect me for the altered service, but by then, i will have a new panel there to feed it.

jeeze, it's just pouring down rain out there again, but at least i dont have to worry about the trailer being grounded. just how much water is in the bottom of that ditch and if i'll drown.

thanks alot for the quick answers. helps alot. am going to try to get it done today.

 

[G._S._Ohm]

How will you test your setup?

How many ways are there to test this setup to be reasonably sure that it is safe?
With rain, you'd apparently want less than 2vac between any conducting surfaces that are nearby to each other.

 

[petersonra]

Not having a grounding electrode is unlikely to be that much of a hazard.

Not having an EGC is far more likely to be a hazard as there will be no way to clear a ground fault.

 

[hillbilly1]

I would leave your ground connected on the mast, adding the ground to the steel grate will not hurt anything, but connecting to it and removing the ground connection from mast will set up the possibility of shock or electrocution because you have two different ground planes now. Never rely on the grounding electrode as the sole means of grounding!

 

[kwired]

Just exactly what is this "trailer"?

My biggest concern is some poor guy (like a plumber) may be crawling underneath to do some work and he comes into contact with a metal frame that has elevated voltage from earth, because of voltage drop on the neutral. The risk of this happening is much higher when the metal frame is bonded to the current carrying neutral than to a non current carrying equipment grounding conductor. Yes they are both bonded together at the service equipment, but the fact that the neutral carries current means there is voltage drop on it anytime it is carrying current.

When well grounded because worker is laying on the ground while working underneath the trailer, a pretty low voltage can easily kill him, where if he were standing on both feet with boots on he may not even feel the same voltage.

This has happened many times before with mobile homes, and likely is #1 reason why the service is not permitted on a mobile home and you must run separate grounded and equipment grounding conductors to a mobile home. This has been a requirement for mobile homes for a very long time.

 

[bullheimer]

i did leave the ground connected to the neutral at the mast, and ran a #4 to the steel frame in the black top. i am actually going to pull a permit, because the ahj here demands that anything be called in for inspection w/i 3 days of being heated up. so i am sure the Port will tell them exactly when i installed it, so i have to pull the permit now. i will have to install a D/C on the pole, 30 ft or not, i think i can actually fudge THAT part (or make the Port move the damned thing closer to the pole). i will just get a correction or ten, and fix them. better than getting caught w/o a permit, as i have an interview for inspectorship in two weeks. that just wouldn't look good on my resume'!
:dunce:
ps kwired, there is no plumbing in this trailer at all. MY biggest concern was the metal hand railing. however, none of these longshoremen are likely to be working without any shoes on.

 

[kwired]

i did leave the ground connected to the neutral at the mast, and ran a #4 to the steel frame in the black top. i am actually going to pull a permit, because the ahj here demands that anything be called in for inspection w/i 3 days of being heated up. so i am sure the Port will tell them exactly when i installed it, so i have to pull the permit now. i will have to install a D/C on the pole, 30 ft or not, i think i can actually fudge THAT part (or make the Port move the damned thing closer to the pole). i will just get a correction or ten, and fix them. better than getting caught w/o a permit, as i have an interview for inspectorship in two weeks. that just wouldn't look good on my resume'!
:dunce:
ps kwired, there is no plumbing in this trailer at all. MY biggest concern was the metal hand railing. however, none of these longshoremen are likely to be working without any shoes on.

What is the penalty for correction notices? Around here they have changed it a few years back. It is now in the installers best interest to get it right the first time, or at very least the second time. First reinspection fee is $50.00, Second is $100.00.

If you are required to put a service disconnect on a separate structure, I don't see any way around separate neutral and ground beyond that disconnect with 2008 or 2011 NEC.

 

[bullheimer]

yes, i am going to get nailed for sure. there is no penalty for corrections, but they do make a note and then publish a list of the top offenders! a wall of shame, if you will.

there is only an additional Trip Fee, which is about $42.00. i am going to use the new panel as the disconnect. that has been my plan anyway, except the boobs at the Port are still trying to decide if they want a private meter there or not (as is currently, and, as they have stated they don't need anymore). the only way i can feed this thing thru the air is by NOT using the currently called for Combo Meter/Panel, because i got to get my feeders back up to the pole, and in a combo you are prevented from doing this with a divider. Since both incoming and outgoing are both fused, i will be allowed to send the feeders to the trailer back up the mast. at least that's the plan. but i don't know if i will be given enough time for me to do the correction, to allow for the port to pull it's head out and bust a move. i guess if the ahj pulls the plug on their trailer, that might lite a fire under their bum.

 

[bullheimer]

ahj said yest. that the way the refinery guys do it is running a 22223 SO cable to it, up the side to the mast.
'
i was like 'Oh Joy" , until i priced it out at $6+ per foot and i need 80 cause the trailer mast is 60 ft away and 10 up one side and 6 the other. so i told them to move the trailer. $700!

they replied the start date is now after krimmas, so i 'decommissioned' it, so can wait to fix it till they start.

 

[bullheimer]

too many 2's. i meant 2223 and cord, not cable. it got inspected today. pretty much the conclusion i came to is using overhead is OUT. HE sited a pile of articles in Art. 550. Which surprised me as i thought i was dealing with 552.

In particular: 550.4, .32A and .33A, also 225.19A (8ft rule), 230.30 and 250.32B, which is, i guess because the feeder to the building we are doing with the existing panel only has 3 wire feeding it, so 250.32B exception will keep us from having to run 4 wire the whole way.

32 is the 30ft disconnect rule and 33 is, basically, saying i HAVE to use CORD.

so then WHY do these trailers even come with a MAST??:happysad:

i am going to have them move the trailer, which was the big plan anyway, and now they agree to do, and come out of a 60A breaker in the panel i am going to throw away, feed a small disconnect on the outside w/in site of the trailer, and then buy a much short cord of not 2223, but 666whatever (10?) or 8. much cheaper, code compliant, and i have at least 15 days, which gets me thru past Crimmas when the boat leaves and maybe no longshormens is around. best part of the whole thing is with the feeder being on a breaker, i don't need the power co to do a d/c.

Just by FREAK OF LUCK i got a call to bid an almost exact same thing yesterday as well. a dirt pit got corrections similar to mine for a 340 ft SO cord feeding a job trailer, same exact thing as the other, i swear to Buddah! unreal. I was planning on doing overhead from a moble home service next to it, with a mast, now i guess i will have to run cord up the side and into the mast as well. again...WHEN can you run overhead to these stupid trailers? i just dont get it!

 

[kwired]

too many 2's. i meant 2223 and cord, not cable. it got inspected today. pretty much the conclusion i came to is using overhead is OUT. HE sited a pile of articles in Art. 550. Which surprised me as i thought i was dealing with 552.

In particular: 550.4, .32A and .33A, also 225.19A (8ft rule), 230.30 and 250.32B, which is, i guess because the feeder to the building we are doing with the existing panel only has 3 wire feeding it, so 250.32B exception will keep us from having to run 4 wire the whole way.

32 is the 30ft disconnect rule and 33 is, basically, saying i HAVE to use CORD.

so then WHY do these trailers even come with a MAST??:happysad:

i am going to have them move the trailer, which was the big plan anyway, and now they agree to do, and come out of a 60A breaker in the panel i am going to throw away, feed a small disconnect on the outside w/in site of the trailer, and then buy a much short cord of not 2223, but 666whatever (10?) or 8. much cheaper, code compliant, and i have at least 15 days, which gets me thru past Crimmas when the boat leaves and maybe no longshormens is around. best part of the whole thing is with the feeder being on a breaker, i don't need the power co to do a d/c.

Just by FREAK OF LUCK i got a call to bid an almost exact same thing yesterday as well. a dirt pit got corrections similar to mine for a 340 ft SO cord feeding a job trailer, same exact thing as the other, i swear to Buddah! unreal. I was planning on doing overhead from a moble home service next to it, with a mast, now i guess i will have to run cord up the side and into the mast as well. again...WHEN can you run overhead to these stupid trailers? i just dont get it!

Does the trailer have a nameplate? If it is an ART 550 mobile home it will have a nameplate stating it is such, I believe the same thing goes for RV's, park trailers, and manufactured homes.

If it is not made by a manufacturer of the mentioned types of structures (say it is a home made one of a kind) then who knows what the AHJ will call it. But if it is on wheels I can't see many wanting it to be supplied via service conductors.

 

[bullheimer]

i was just asked that same question by a different inspector!

apparently if there is a nameplate it would allow overhead. he wasnt the one who went out there tho, and i have to wait to talk to him. i guess i am just going to have to let go of the whole overhead concept tho. man what a can of worms

 

[RUWired]

i was just asked that same question by a different inspector!

apparently if there is a nameplate it would allow overhead.

Check the load center cover. There should be a sticker saying what type of building it is.

 

[kwired]

apparently if there is a nameplate it would allow overhead.

Not necessarily. Mobile homes can not have the service mounted on them, so if there would be overhead conductors supplying a mobile home they can not be service conductors. Actually 550.10(I)(1) does permit overhead mast type supplied by a feeder, but does not permit supply to be service. 550.32 is still going to require the service disconnect (or a disconnecting means, if supplied by a feeder) to be located within sight and within 30 feet of the mobile home.

Manufactured homes can have the service equipment mounted on them. But a manufactured home will not have a frame and wheels under it except when being moved.

The nameplate will often be on the lower outside wall near the intended point of entry of electrical supply. Sometimes additional information will be at the panelboard also.

 

[powerplay]

Just exactly what is this "trailer"?

My biggest concern is some poor guy (like a plumber) may be crawling underneath to do some work and he comes into contact with a metal frame that has elevated voltage from earth, because of voltage drop on the neutral. The risk of this happening is much higher when the metal frame is bonded to the current carrying neutral than to a non current carrying equipment grounding conductor. Yes they are both bonded together at the service equipment, but the fact that the neutral carries current means there is voltage drop on it anytime it is carrying current.

When well grounded because worker is laying on the ground while working underneath the trailer, a pretty low voltage can easily kill him, where if he were standing on both feet with boots on he may not even feel the same voltage.

Does connecting a ground to the ungrounded conductor trailer panel bonded to the frame/metal parts make it safer, or still a difference in potential from a fault clearing neutral carrying current back to source and equipment bonding to a ground plate not carrying current?

 

[kwired]

Does connecting a ground to the ungrounded conductor trailer panel bonded to the frame/metal parts make it safer, or still a difference in potential from a fault clearing neutral carrying current back to source and equipment bonding to a ground plate not carrying current?

I'm not sure I understand what you are asking.

If the trailer frame/other metal parts are bonded to a current carrying neutral, there will be voltage drop on said neutral, how much depends on size of conductor and amount of load on the conductor. You are effectively bringing this voltage to the metal frame because it is all connected together in the main panel. Now the poor unsuspecting plumber crawling under the trailer is laying on "true earth potential" but a one volt drop on the supply neutral is also present on the steel frame if it is bonded to the supply neutral. That same one volt may not be felt when standing on two feet with shoes on, but when laying on the ground the plumber has a lot more earth contact and has a much better chance of feeling even one volt, if his body is exposed to 5-10 volts enough current may flow that he may be electrocuted.

Bond that trailer frame to a (normally) non current carrying equipment grounding conductor and you have less voltage drop from the neutral present at the frame - you will still have whatever voltage drop there is present at the service equipment, you could also have voltage present because of voltage drop on the POCO's primary neutral. This is not normally a problem but not impossible either. It does show up more often in areas where bodies of water are involved or around animals or livestock operations - especially larger animals that have a wide base between front and rear legs as they are more capable of simultaneously contacting points in the earth that are farther apart and may be at different potentials.

 

[bullheimer]

got them to move it on the 2nd. will run a cord to it off a disco on the outside of my building from a 60A breaker, then should be done with it. i got charged a $45 trip fee for them to tell me how they want it.

it is currently for the last three weeks, but grounded to the storm drain grids' frame, directly underneath it. i think the plumber would be okay if they had plumbing, that is.