480.7 DC Disconnect Methods

[MDC]

I have a battery system inside a shelter and was wondering if the Main Breaker inside my DC load center would be fine instead of installing a disconnect. The battery system is 130 VDC. I have read about readily accessible and it says a panel door with a lock is an exception but what about the within sight of. The panelboard is about 15' away from the battery system. You would not be able not see the breaker unless the door was opened.

 

[Rick 0920]

I would personally err on the side of caution in this circumstance. Even if an exception allows this, the best practice would be to have a disconnecting means within sight of your equipment.

 

[MDC]

Thank you for the reply. It also states in article 230.70 (B) that each service disconnect shall be permanently marked to identify it as a service disconnect. That is what I will go with.

 

[tortuga]

Thank you for the reply. It also states in article 230.70 (B) that each service disconnect shall be permanently marked to identify it as a service disconnect. That is what I will go with.

Unless I missed something a 130 VDC battery system is not a 'service' so nothing in article 230 would technically apply. See also 240.21(H)

 

[jaggedben]

Yes article 230 is irrelevant.

You say 'battery system' so is this just battery cells (article 480) or is it an ESS (Article 706)? The latter requires a disconnect within 5ft of the ESS or if the conductors go through a partition.

Otherwise if your disconnect is within sight of the batteries then you seem to be okay by Article 480.

 

[MDC]

It is Storage Batteries, so it would fall under article 480. I was just wondering would the main breaker in the DC Panel be considered as a disconnect means. I think good practice would be to add a Disconnect.

 

[tortuga]

It is Storage Batteries, so it would fall under article 480. I was just wondering would the main breaker in the DC Panel be considered as a disconnect means. I think good practice would be to add a Disconnect.

Just out of curiosity what type of charge controller / inverter are you using?

 

[jaggedben]

It is Storage Batteries, so it would fall under article 480. I was just wondering would the main breaker in the DC Panel be considered as a disconnect means. I think good practice would be to add a Disconnect.

What charges the batteries? Isn't there another connection to a charge controller or something in between the batteries and the load center? (Or is the DC panel a combiner panel for the battery outputs?)

The battery disconnect needs to isolate the batteries from everything else, both charging source and loads. So if the main breaker in the panel only isolates the loads then you do need another disconnect.

 

[MDC]

What charges the batteries? Isn't there another connection to a charge controller or something in between the batteries and the load center? (Or is the DC panel a combiner panel for the battery outputs?)

The battery disconnect needs to isolate the batteries from everything else, both charging source and loads. So if the main breaker in the panel only isolates the loads then you do need another disconnect.

The current setup that is in place is a 130 vdc battery system. The battery system conductors are terminated in the main dc panelboard breaker which is 15 feet away from the battery system. The battery charger (rectifier) is ran to a 30 amp breaker located in the dc panelboard. This is the current setup.

 

[jaggedben]

Ok. I'm still unclear if the panelboard is within sight of the batteries. If yes, the existing setup sounds compliant. If not, you need another disconnect. If the door you refer to in the first post is to the battery room, not compliant in my opinion. If the door is the door of the panelboard, I think it's fine but it would be prudent to put a 'Battery Disconnect' sign or label on the outside cover of the panelboard. There's also some labeling requirements in 480.

 

[MDC]

Ok. I'm still unclear if the panelboard is within sight of the batteries. If yes, the existing setup sounds compliant. If not, you need another disconnect. If the door you refer to in the first post is to the battery room, not compliant in my opinion. If the door is the door of the panelboard, I think it's fine but it would be prudent to put a 'Battery Disconnect' sign or label on the outside cover of the panelboard. There's also some labeling requirements in 480.

Ok. Sorry for the misunderstanding. I see your point because even thought it is 15' away it could still be behind something. It is within sight of. I'm not clear on the grounding article 250.168. Does this only apply to 250.166 (A).

 

[tortuga]

I'm not clear on the grounding article 250.168. Does this only apply to 250.166 (A).

250.168 applies to all DC systems that are required to be grounded per 250.162

 

[MDC]

250.168 applies to all DC systems that are required to be grounded per 250.162

So in article 250.168 it talks about the bonding jumper shall be used to connect the equipment grounding conductor to the grounded conductor at the first source or disconnect. Does this mean the negative from the batteries would be on an insulator in the panel and from there the bonding jumper would go to the can where the equipment grounding conductors are located and then a grounding electrode conductor would go out to the ground ring, plate, rod, etc. Does this sound right.

 

[jaggedben]

So in article 250.168 it talks about the bonding jumper shall be used to connect the equipment grounding conductor to the grounded conductor at the first source or disconnect. Does this mean the negative from the batteries would be on an insulator in the panel and from there the bonding jumper would go to the can where the equipment grounding conductors are located and then a grounding electrode conductor would go out to the ground ring, plate, rod, etc. Does this sound right.

More or less. The negative terminal bar would not need to be isolated in that case.

Are you absolutely sure it's okay to ground this system? The rectifier is galvanically isolated? If it isn't, you're going to have a massive short. Please be careful.

See Exception 2 under 250.162(A).

 

[tortuga]

Ha Ben we were typing at the same type. I was just about to say make sure its supposed to be grounded. Also make sure you know which wire is supposed to be grounded, its not necessarily the negative thats grounded, I have worked on many positive grounded systems. Don't ask me why but it was a 'standard practice' at a large multinational company.