Mobile home panel

Status
Not open for further replies.
S

Stevenfyeager

Senior Member
Location
United States, Indiana
Occupation
electrical contractor
My friend’s 1990 mobile home is fed from a panel outside on a utility pole with three wires. In his mobile home panel, the grounds are on one ground bar bonded to the enclosure but the neutrals are connected to an isolated neutral bar. No ground rod at the mobile home. My instructor always told us when there are just 3 wires to a subpanel to another building , you DON’T separate the ground and neutral and you drive a ground rod. Am I correct? Thank you
 
Stevenfyeager said:
My friend’s 1990 mobile home is fed from a panel outside on a utility pole with three wires. In his mobile home panel, the grounds are on one ground bar bonded to the enclosure but the neutrals are connected to an isolated neutral bar. No ground rod at the mobile home. My instructor always told us when there are just 3 wires to a subpanel to another building , you DON’T separate the ground and neutral and you drive a ground rod. Am I correct? Thank you
Click to expand...

No, article 550 for many years now would have required a 4 wire feeder in that application
 
Stevenfyeager said:
My friend’s 1990 mobile home is fed from a panel outside on a utility pole with three wires. In his mobile home panel, the grounds are on one ground bar bonded to the enclosure but the neutrals are connected to an isolated neutral bar. No ground rod at the mobile home. My instructor always told us when there are just 3 wires to a subpanel to another building , you DON’T separate the ground and neutral and you drive a ground rod. Am I correct? Thank you
Click to expand...

Mobile home changes things. This should be a 4 wire feeder, unless there was some local code that said otherwise at the time.

FWIU, some areas would allow this to be fed three wire if it were on a permanent foundation with axles and tires removed. You would then bond the N-EG and establish a GES.
 
ptonsparky said:
Mobile home changes things. This should be a 4 wire feeder, unless there was some local code that said otherwise at the time.

FWIU, some areas would allow this to be fed three wire if it were on a permanent foundation with axles and tires removed. You would then bond the N-EG and establish a GES.
Click to expand...

Right now it is an un-safe condition with no fault clearing path

someone should check what needs to be done to correct that
 
Stevenfyeager said:
My friend’s 1990 mobile home is fed from a panel outside on a utility pole with three wires. In his mobile home panel, the grounds are on one ground bar bonded to the enclosure but the neutrals are connected to an isolated neutral bar. No ground rod at the mobile home. My instructor always told us when there are just 3 wires to a subpanel to another building , you DON’T separate the ground and neutral and you drive a ground rod. Am I correct? Thank you
Click to expand...

ptonsparky said:
Agree. Could have been that way for close to 29 years now. I do wonder why more people are not electrocuted.
Click to expand...

I agree with everyone that it's not wired correctly.

The mobile home probably does have a ground (of sorts). The panel on a mobile home comes from the factory with the ground at panel bonded to the mobile home frame. Mobile homes are typically tied down with metal straps and and tie downs screwed into the earth. This is not a legal ground system but probably would save a person from electrocution.
 
One of the biggest dangers is for someone like a plumber or electrician to be crawling under the home to work and getting electrocuted when they contact the frame that is energized from a fault.

Standing on both feet with shoes on raises resistance you have to earth, laying on the ground under the home lowers your resistance to earth - more contact surface.
 
growler said:
I agree with everyone that it's not wired correctly.

The mobile home probably does have a ground (of sorts). The panel on a mobile home comes from the factory with the ground at panel bonded to the mobile home frame. Mobile homes are typically tied down with metal straps and and tie downs screwed into the earth. This is not a legal ground system but probably would save a person from electrocution.
Click to expand...

growler said:
This is not a legal ground system but probably would save a person from electrocution.
Click to expand...

You know I like a lot of your post here, but not this one. Your saying it is relatively safe and i strongly disagree. There is no way to clear the fault so it floats on the metal frame leaving the danger of someone getting hurt'
 
david said:
You know I like a lot of your post here, but not this one. Your saying it is relatively safe and i strongly disagree. There is no way to clear the fault so it floats on the metal frame leaving the danger of someone getting hurt'
Click to expand...

I agree, if bonding screw were installed on the mobile home panel then it would be a more like a service supplied building, but with no bonding jumper you are still using earth and some crude electrodes as a fault return path. If you only achieve 10 ohms resistance with the tie downs then fault current is only going to be 12 amps - not even going to trip a 15 amp overcurrent device.
 
kwired said:
I agree, if bonding screw were installed on the mobile home panel then it would be a more like a service supplied building, but with no bonding jumper you are still using earth and some crude electrodes as a fault return path. If you only achieve 10 ohms resistance with the tie downs then fault current is only going to be 12 amps - not even going to trip a 15 amp overcurrent device.
Click to expand...
So, if I get out to this friend's mobile home (a long drive), and it is a 3 wire with separated neutral and grounds,(floating neutral bar) like the photo he sent me looks, I should join the two bars together in his mobile home panel, and drive a ground rod, correct ?
 
Stevenfyeager said:
So, if I get out to this friend's mobile home (a long drive), and it is a 3 wire with separated neutral and grounds,(floating neutral bar) like the photo he sent me looks, I should join the two bars together in his mobile home panel, and drive a ground rod, correct ?
Click to expand...
If only three wires feed the main panel bond the N&G. Also look for other electrodes that may be present. A metal well casing?

Sent from my SM-T350 using Tapatalk
 
Stevenfyeager said:
So, if I get out to this friend's mobile home (a long drive), and it is a 3 wire with separated neutral and grounds,(floating neutral bar) like the photo he sent me looks, I should join the two bars together in his mobile home panel, and drive a ground rod, correct ?
Click to expand...

Since you posted on an NEC forum , to bond the panel in accordance with article 550 and the manufactures instructions with an exterior service disconnect you need a four wire feeder to the distribution panel

I guess you could follow the advice of other solutions, but you should be asking what does the NEC require.
 
david said:
Since you posted on an NEC forum , to bond the panel in accordance with article 550 and the manufactures instructions with an exterior service disconnect you need a four wire feeder to the distribution panel

I guess you could follow the advice of other solutions, but you should be asking what does the NEC require.
Click to expand...
The NEC doesn't require anything! In Ohio, you may remain under the code under which it was installed. Sound like this might be in an area without an AHJ.

This is where we dig out the old code books and see what would be both Safe and Code compliant at that time.

This 'sounds like the bonding screw was not installed. So install one.

Sent from my SM-T350 using Tapatalk
 
Status
Not open for further replies.
Top