Bonding the Neutral

[jonny1982]

A little confused on when to bond the neutral. If there is a MDP (Main Distribution Panel) when would it get bonded in there? If I had metering and a main disconnect before the MDP, would it take place in there? Would it be in both at the same time?

 

[jonny1982]

A little confused on when to bond the neutral. If there is a MDP (Main Distribution Panel) when would it get bonded in there? If I had metering and a main disconnect before the MDP, would it take place in there? Would it be in both at the same time?

FYI, this is a 1200 amp commercial MDP

 

[iwire]

It is required that we bond the neutral in the enclosure containing the service disconnecting means and with very few exceptions no place beyond that.

However on the supply side of the service disconnect it is often bonded in the meter / CT enclosure as well.

 

[jonny1982]

It is required that we bond the neutral in the enclosure containing the service disconnecting means and with very few exceptions no place beyond that.

However on the supply side of the service disconnect it is often bonded in the meter / CT enclosure as well.

Ok, so when you say enclosure containing the service disconnecting means, do you mean the 1200 amp main distribution panel or further upstream like if I had a fused 1200 amp disconnect. Lets say I had a 1200 amp fused disconnect feeding a main lug (no main breaker) main distribution panel. Would I bond the neutral in the disconnect or the main distribution panel.

Another example, lets say I had a 200 amp breaker at the meter stack feeding a main lug only main distribution panel. Would I bond the neutral at the meter stack or the main distribution panel. If it is at the meter stack, why do MDP's always come with a neutral bonding strap?

 

[jonny1982]

It is required that we bond the neutral in the enclosure containing the service disconnecting means and with very few exceptions no place beyond that.

However on the supply side of the service disconnect it is often bonded in the meter / CT enclosure as well.

Is it bonded at the first means of disconnect, wherever it may be? There seems to be a lot of confusion on this.

 

[Dennis Alwon]

Johhny if you have a meter and a disconnect that feeds the main distribution panel then the bonding only gets done at the main disconnect not in the main distribution panel. Often the main distribution panel is the service disconnect but it seems like you have a disconnect ahead of the MDP. If that is the case then do not bond the MDP and you need to carry an equipment grounding conductor or use the metallic raceway as the grounding of the mdp. That MDP must have the neutral isolated from the can

 

[mopowr steve]

Is it bonded at the first means of disconnect, wherever it may be? There seems to be a lot of confusion on this.

Yes,
OK try not to read into it to much,
1st means of disconnect would be the fused or breaker disconnect before your MDP in your case. So you would bond the neutral there and everything down stream would have a separate neutral and grounding.
Your MDP comes with a bonding strap in case it would be the first means of disconnect. Otherwise it does not get used. And the separate grounding bar that may come with it would be installed. Of course this bar could also be used for grounds even when the MDP is the 1st means of disconnect with bonding strap installed.

 

[Smart $]

Is it bonded at the first means of disconnect, wherever it may be? There seems to be a lot of confusion on this.

Stating the system has a neutral, we have to assume it is a grounded system. On the POCO side of the service disconnecting means (SDM), all exposed, non-conducting metallic parts are bonded to the neutral [grounded conductor].

This system is required to have the Main Bonding Jumper (MBJ) installed in the SDM enclosure, between the neutral and equipment grounding system (EGS).

On the consumer side of the SDM, no neutral is to be bonded to the EGS (except separately derived systems that have a grounded neutral conductor).

Keep in mind that some POCO's, for some systems, may require a disconnect (typically non-fused) on the supply side of the meter or CT cabinet for maintenance purposes. This is not the SDM.