Residential Subpanel

[Will Wire]

I?m working on a house that was built in the late 1950s or early 1960s. The house was built with circuits without equipment grounds. A subpanel was installed in the garage. The neutral buss of the subpanel is isolated from the enclosure and there is no ground bar. Over the years people have installed new circuits and have connected the equipment grounds to the neutral buss. A couple of years ago the main service entrance equipment was upgraded and the existing subpanel was fed with a four wire feed and both the ground and the neutral wires were attached to the neutral buss bar. Is this unsafe? Why? My understanding has been that the neutrals and grounds are connected to the neutral buss at the main service and no where else unless the panel is located in a separate building. Thank you for your attention to this matter, Trent

 

[lakee911]

I?m working on a house that was built in the late 1950s or early 1960s. The house was built with circuits without equipment grounds. A subpanel was installed in the garage. The neutral buss of the subpanel is isolated from the enclosure and there is no ground bar. Over the years people have installed new circuits and have connected the equipment grounds to the neutral buss. A couple of years ago the main service entrance equipment was upgraded and the existing subpanel was fed with a four wire feed and both the ground and the neutral wires were attached to the neutral buss bar. Is this unsafe? Why? My understanding has been that the neutrals and grounds are connected to the neutral buss at the main service and no where else unless the panel is located in a separate building. Thank you for your attention to this matter, Trent

It's my understanding that all subpanels need to have the ground a nuetral seperated. At the service enterance is the only place where they can be connected. You're lucky that they ran 4W though...if they were just going to connect them together at the subpanel, I'm surprised they bothered. I don't know the exact reasoning for the seperation, but it's likely something to do with fauly currents. Someone will chime in, I'm sure.

 

[Jim W in Tampa]

It's my understanding that all subpanels need to have the ground a nuetral seperated. At the service enterance is the only place where they can be connected. You're lucky that they ran 4W though...if they were just going to connect them together at the subpanel, I'm surprised they bothered. I don't know the exact reasoning for the seperation, but it's likely something to do with fauly currents. Someone will chime in, I'm sure.

That is just flat out stupid. They knowed enough to run 4 wire but did not know what to do with it. Get's scary to think we have guys like that wiring. What must be done now is seperate the grounds and neutral and only bond the box to the ground. What you have now is parralel neutral if both sides connected together. As far as safe i don't see a major fire hazard but it should get fixed

 

[resistance]

I agree with Jim.

Is this unsafe? Why?

During a normal day it will create two paths back to the source of power--the neutral transporting current for the most part, unless the loads are balanced.
Safe or unsafe, you tell us

 

[stevebea]

I?m working on a house that was built in the late 1950s or early 1960s. The house was built with circuits without equipment grounds. A subpanel was installed in the garage. The neutral buss of the subpanel is isolated from the enclosure and there is no ground bar. Over the years people have installed new circuits and have connected the equipment grounds to the neutral buss. A couple of years ago the main service entrance equipment was upgraded and the existing subpanel was fed with a four wire feed and both the ground and the neutral wires were attached to the neutral buss bar. Is this unsafe? Why? My understanding has been that the neutrals and grounds are connected to the neutral buss at the main service and no where else unless the panel is located in a separate building. Thank you for your attention to this matter, Trent

Things thatmake you say hmmmm. I always have to shake my head when I pull a sub-panel cover off and the ground and neutral of the SER cable are both landed on the neutral bar with the bonding screw installed.

 

[infinity]

Is the garage attached?

 

[Will Wire]

Thanks everyone! I did find an explanation in the NEC handbook that concerns the safety issues. The garage is attached.