Can you back feed power through fused bucket switchboard?

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elecguy

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I have a client that wants to feed power they have stored (not from solar) back into their system. Their existing switchboard is an old fused bucket switchboard. Can this be done? Thanks!
 
elecguy said:
I have a client that wants to feed power they have stored (not from solar) back into their system. Their existing switchboard is an old fused bucket switchboard. Can this be done? Thanks!
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If they follow the rules for such things. I don't recall there is any prohibition on the use of fused switchboards versus those with circuit breakers.
 
The switch blades and fuses must be deenergized when the switch is in the Off position. In general, you cannot "backfeed" fusible equipment.
 
jim dungar said:
The switch blades and fuses must be deenergized when the switch is in the Off position. In general, you cannot "backfeed" fusible equipment.
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Unless, as with PV systems, the source of the backfed power shuts down when the switch is opened.
 
ggunn said:
Unless, as with PV systems, the source of the backfed power shuts down when the switch is opened.
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I think Jim by backfeed is referring to the practice of bringing power in the load side terminal and out the line side terminals which is not permitted for fused disconnects. However, you could disconnect the line side from the bus and connect the load side to the bus and bring the battery generated power into the line side. But it is more work and depending on the hardware might require one to replace the fused disconnect. I think it is doable, but not as simple as just bringing the wiring in and hooking it up.
 
There is a lot else in play here too, such as isolating that stored energy source in the event of a utility failure so that you are not backfeeding into utility lines and potentially killing linemen.

People like to come up with all sorts of harebrained schemes with regard to alternative energy systems on the cheap, it’s up to us professionals to keep them on the straight and narrow with regard to safety and code compliance.
 
jim dungar said:
The switch blades and fuses must be deenergized when the switch is in the Off position. In general, you cannot "backfeed" fusible equipment.
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Not arguing, but want to understand completely. Have seen this done regularly with circuit breakers, sometimes with interlocking "Kirk" keys. Do you have a reference?
 
TwoBlocked said:
Not arguing, but want to understand completely. Have seen this done regularly with circuit breakers, sometimes with interlocking "Kirk" keys. Do you have a reference?
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Breakers can be back fed, unless marked with "Line and Load".
Fuse compartments with Kirk keys may be acceptable to some AHJs.
Almost every manufacturer of a bolted pressure style visible switch offers a 'bottom fed" or back fed version.
 
We back feed fused disconnect switches for CoGen input all of the time. They require labeling according to Article 705.

705.12(B)
(4) Suitable for Backfeed. Circuit breakers, if backfed, shall be suitable for such operation.
Informational Note: Fused disconnects, unless otherwise marked, are suitable for backfeeding.
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Does 690 cover this type of question for servicing the fuse.
Been a while and I will read.
Memory; if you have to service the fuse of a back feed PV source fused disconnect. Your required to have an isolation point ahead of that back feed source. With labeling.

Have some coffee and morning reading for myself.

Now should you you back feed this bucket, I would not. I also have to ask is this one of those old six handle set ups with each being a service disconnect.
 
elecguy said:
I have a client that wants to feed power they have stored (not from solar) back into their system. Their existing switchboard is an old fused bucket switchboard. Can this be done? Thanks!
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I would like to here more about this.
Before I start reading more I would like to understand a few things about this stored power type. Then I ask if any NEC section applies to this source. Then judge the tie based on this.

So my first question is the what voltage and type of system.

Second question what is the source of this stored energy.

Then what artical in the NEC applies to which part.

Take some of the quess work out of the ansawer.
An example would be equipment over 1000 volts. 490.21 would apply.

If you do not mind sharing a little more info I would like to take it as a learning exercise for my self.

Otherwise as a rule no back feed of a fused safety switch unless permitted by an NEC article. I have read from some mfg of fused safety switches that no back feed is allowed. Not knowing if your bucket is listed for that purpose. I would say no and start there. Then move forward to the rest of the design.
Now a listed piece of equipment designed for that purpose I would say yes and use applicable NEC articles.

If that bucket fed a CB enclosure I would think it no different then. A single family dwelling using a fused switch ( service disconnect or em disc.) feeding a load center with a back feed device. Do some labeling and your good.

look forward to learning something from this question.
Thank you
 
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