In line fuses? (100A and up?)

[jaggedben]

I'm considering in-line fuses as an overcurrent device to protect feeders downstream from a tap to a solar source. This follows 705.12(D)(2)(1) in the 2014 code. Basically it could allow me to deal with the situation where a customer has a service panel that consists only of a single breaker feeding a sub well inside the house. I'd tap the feeder to a disconnect for the solar, and put the in-line fuses to protect against the potential issue of the utility+solar overloading the feeder. (Not a real problem, but that's another discussion....) It would be a lot easier than installing a new subpanel and bringing the feeder back and forth.

The only thing is... I've never actually seen in-line fuses like this and I'm not sure what product exists that would actually be suitable. The most likely fuse ratings I'd need would be 100, 125, and 200. Googling 'in-line fuses' gets me all automotive results not suitable.

Anybody have any product suggestion, or can confirm that such things would work for what I'm talking about?

Other thoughts? Pitfalls?

 

[SceneryDriver]

I'm considering in-line fuses as an overcurrent device to protect feeders downstream from a tap to a solar source. This follows 705.12(D)(2)(1) in the 2014 code. Basically it could allow me to deal with the situation where a customer has a service panel that consists only of a single breaker feeding a sub well inside the house. I'd tap the feeder to a disconnect for the solar, and put the in-line fuses to protect against the potential issue of the utility+solar overloading the feeder. (Not a real problem, but that's another discussion....) It would be a lot easier than installing a new subpanel and bringing the feeder back and forth.

The only thing is... I've never actually seen in-line fuses like this and I'm not sure what product exists that would actually be suitable. The most likely fuse ratings I'd need would be 100, 125, and 200. Googling 'in-line fuses' gets me all automotive results not suitable.

Anybody have any product suggestion, or can confirm that such things would work for what I'm talking about?

Other thoughts? Pitfalls?

What about a fused disconnect? Would that satisfy your requirements? If that doesn't work, would this fit the bill:

http://www.automationdirect.com/adc...ders,_Fuse_Blocks,_-a-_Accessories/R25100-2CR

Place that block in an enclosure, and you're all set.



SceneryDriver

 

[augie47]

Would 240.40 affect your plan ?

 

[jaggedben]

Thanks for the responses.

What about a fused disconnect? Would that satisfy your requirements? If that doesn't work, would this fit the bill?

Place that block in an enclosure, and you're all set.

The whole point here is to avoid installing another enclosure and running the existing feeder out to it and then back to the service enclosure to splice it.

I don't see it as being compliant to put a fuse block with exposed terminals into an enclosure that was listed for something else. But if it's an insulated device that isn't required to be mounted then I think the only issue is wiring space. Perhaps such a thing only exists in my head though.

Would 240.40 affect your plan ?

I don't see why, if I have a disconnecting means in the same enclosure (i.e the service disconnect breaker).

 

[kwired]

I'm considering in-line fuses as an overcurrent device to protect feeders downstream from a tap to a solar source. This follows 705.12(D)(2)(1) in the 2014 code. Basically it could allow me to deal with the situation where a customer has a service panel that consists only of a single breaker feeding a sub well inside the house. I'd tap the feeder to a disconnect for the solar, and put the in-line fuses to protect against the potential issue of the utility+solar overloading the feeder. (Not a real problem, but that's another discussion....) It would be a lot easier than installing a new subpanel and bringing the feeder back and forth.

The only thing is... I've never actually seen in-line fuses like this and I'm not sure what product exists that would actually be suitable. The most likely fuse ratings I'd need would be 100, 125, and 200. Googling 'in-line fuses' gets me all automotive results not suitable.

Anybody have any product suggestion, or can confirm that such things would work for what I'm talking about?

Other thoughts? Pitfalls?

You lost me, you want to put in a disconnect then put in downstream fuses - but don't want to install an additional enclosure - doesn't a fused disconnect take care of all this?

There are fuse blocks, but you generally want or need a disconnecting means to be able to safely replace a fuse. As you said most "inline" products are more of an automotive related product, but you do find them or similar products for 30 amp or less applications.

 

[jaggedben]

I don't want to put in a disconnect. The whole point is to not put in a new disconnecting means for the feeder. (The solar will get a new disconnect, but not the feeder.)

Perhaps a picture helps. It's representative of a very common situation I run into.



The breaker feeders a subpanel that is installed in one of the interior walls of the house. Running a new circuit to the sub is not practical. (In fact in this case the customer had had a kitchen cabinet installed over the front of it!)

I need to install a solar system. Some AHJs will allow a simple load side tap but this one won't. If I follow the 2014 code and put another overcurrent device downstream of the tap, I am probably good. (In California we go on the 2014 NEC in 2017, but they'll probably accept this.)

On solution is to reconfigure the sub so that the feeder lands on a backfed breaker. Not practical in this case without remodeling the kitchen cabinets. Also not practical in cases where the sub is full.

The solution I adopted in this case was to put a 100A sub in the garage behind the service panel, run new feeder wire from the main to the sub, then run a new 100A feed back to the main and splicing it to the existing wires. Thank goodness the room behind the panel was the garage because if it had been a bedroom this would not have been acceptable, and I would have had to tear apart walls to get the job done, which would have eaten all our profit on this job. The solar breaker went into the new sub.

The alternative idea I'm discussing here is to tap the feeder you see in the picture, and also wire in-line fuses into it, all in the enclosure you see. Now I can come out of the box with a 1/2" conduit to a fused disco for the solar.

But if 100A 240V in-line fuse devices listed for this type of purpose don't exist then it doesn't work.

With 200A services like this, the sub is much, much less cheap and practical. So is landing a backfed breaker to protect a 200A sub. But I can downsize the main breaker to 175 if the customer is okay with that. I can't do that on a 100A service for a single family home because that's the minimum NEC requirement.

 

[GoldDigger]

Your description just popped up a thought that had escaped my attention before.
If POCO will not allow a line side PV connection, will they allow a second service panel in parallel with the original?
If so, put a main breaker in that panel and also put in a backfed PV breaker.
Electrically it is the same as a line side connection but with an extra breaker.
It is not two services to the same building nor is it two feeders as long as the PV connection is a branch circuit rather than a feeder (no AC combiner panel allowed)

Thoughts?

 

[jaggedben]

Your description just popped up a thought that had escaped my attention before.
If POCO will not allow a line side PV connection, will they allow a second service panel in parallel with the original?
If so, put a main breaker in that panel and also put in a backfed PV breaker.
Electrically it is the same as a line side connection but with an extra breaker.
It is not two services to the same building nor is it two feeders as long as the PV connection is a branch circuit rather than a feeder (no AC combiner panel allowed)

Thoughts?

I guess you're proposing to double-lug the meter? In this case it was simpler and faster to install a sub than to do any work on the line side of the main breaker. The point of the idea I'm proposing is to find something even simpler and faster than the sub. It's not a question that comes from not having other options, I'm just trying to find a better option.

It would probably be simpler to just replace the service panel with one that had some distribution, rather than research if double-lugging the meter is possible. If we have to do that kind of work on the service that's what we'll do. We do it all the time, but for me it's a pain to bring in the guy I trust to do that work, I can only have him on so many jobs a week, it's the last resort solution. Not to mention we have to charge more for it, which can slow down or stop the job.

A supply side connection is not feasible in this case because you can't tap the busbars between the meter and the main breaker. If it were feasible I might contact manufacturers about the listing, but in most of these 100A and 200A meter/main combos I just don't view it as physically feasible.

Also, while the AHJ might allow two service panels in parallel, they'd have to be fed from the same meter. The utility might allow a second meter but that would just cost more and more money.

 

[Smart $]

http://www.cooperindustries.com/con...l/products/fuse_holders_andblocks/blocks.html

Why not use a MCCB?