# Disconnect termination ratings



## Wirenuting (Sep 12, 2010)

Why not change the breaker feeding the equipment?

Beyond that, wouldn’t your on-site EE be the one designing and signing off on the install?


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## iwannawaterski (Dec 17, 2019)

This is an industrial production facility where access to change the breaker would require a panel shutdown, resulting in significant loss of production. Changing the breaker is not an option at this point, but thanks for not providing your opinion.


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## VELOCI3 (Aug 15, 2019)

I would think that the wire between the breaker and disconnect needs to be rated for 70 amps. The wire after the fuse should be 60 amps. 


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## micromind (Aug 11, 2007)

VELOCI3 said:


> I would think that the wire between the breaker and disconnect needs to be rated for 70 amps. The wire after the fuse should be 60 amps.
> 
> 
> Sent from my iPhone using Tapatalk


Same here. 

70 amp wire from the breaker to the fuses then 60 after the fuses. Unless you can use the 10' or 25' tap rule. 

P.S. I live in Fernley, howdy neighbor!


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## iwannawaterski (Dec 17, 2019)

OK, people, no one has ACTUALLY answered the question! Never mind what the wire size feeding it is. Never mind if the breaker can be replaced. The question is:

First, can you LEGALLY terminate a 70A circuit to a 60A rated fuse block inside a control cabinet with 60A fuses in it?
Second, you would need a 100A rated dx with 60A fuses in it BEFORE the cabinet to feed it, yes?


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## VELOCI3 (Aug 15, 2019)

iwannawaterski said:


> OK, people, no one has ACTUALLY answered the question! Never mind what the wire size feeding it is. Never mind if the breaker can be replaced. The question is:
> 
> First, can you LEGALLY terminate a 70A circuit to a 60A rated fuse block inside a control cabinet with 60A fuses in it?
> Second, you would need a 100A rated dx with 60A fuses in it BEFORE the cabinet to feed it, yes?




You could use that disconnect to tap off a larger feed as long as you don’t exceed the rating with a fuse larger than 60 amps. Most disconnects are service rated which means you are tapping off a larger rated line. 


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## iwannawaterski (Dec 17, 2019)

VELOCI3, so the dx must be "service rated" then. I'll look into that. If so, then would there be a maximum rating allowed to terminate on it?


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## VELOCI3 (Aug 15, 2019)

iwannawaterski said:


> VELOCI3, so the dx must be "service rated" then. I'll look into that. If so, then would there be a maximum rating allowed to terminate on it?




As long as you don’t exceed the voltage rating and the load fuse size it will be ok. 


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## iwannawaterski (Dec 17, 2019)

So you're saying that you could terminate a 200A circuit (assuming you could fit the wire in, which you couldn't) to a 30A dx as long as the voltage is at or below the rating...


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## VELOCI3 (Aug 15, 2019)

iwannawaterski said:


> So you're saying that you could terminate a 200A circuit (assuming you could fit the wire in, which you couldn't) to a 30A dx as long as the voltage is at or below the rating...




Disconnects are rated for voltage and fuse size. If your engineer has an issue with fault clearance use a lower aic rated fuse


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## iwannawaterski (Dec 17, 2019)

I'm looking at various dx cut sheets. You can actually purchase a 30A dx that will accept #2 wires. So you're saying I can terminate a 115A circuit (max amperage for #2 in 75° column) in a 30A dx, as long as my fuse isn't greater than 30A?


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## VELOCI3 (Aug 15, 2019)

iwannawaterski said:


> I'm looking at various dx cut sheets. You can actually purchase a 30A dx that will accept #2 wires. So you're saying I can terminate a 115A circuit (max amperage for #2 in 75° column) in a 30A dx, as long as my fuse isn't greater than 30A?




Wire size has nothing to do with the rating. 


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## iwannawaterski (Dec 17, 2019)

I'm thinking you really don't understand the question...


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## Forge Boyz (Nov 7, 2014)

Or maybe you don't understand the answer...

ETA the 60A fuses in the disconnect will limit the current on the line side lugs to 60A. The conductors ahead of that need to be sized for the 70A breaker, but you only need a 60A disconnect.
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## iwannawaterski (Dec 17, 2019)

No, I'm clear on the answer. It seems everyone here just thinks a glib reply is supposed to be acceptable like your knowledge is unquestionable....


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## Forge Boyz (Nov 7, 2014)

The code is a permissive document. There is nothing prohibiting this so it is acceptable.

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## VELOCI3 (Aug 15, 2019)

iwannawaterski said:


> No, I'm clear on the answer. It seems everyone here just thinks a glib reply is supposed to be acceptable like your knowledge is unquestionable....




Sorry about that. Wasn’t my intention. 




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## Forge Boyz (Nov 7, 2014)

Think about the tap rules. The minimum size restrictions are about protecting the conductors. You could tap a 30A disconnect off a 400A splitter as long as your conductor size meets the requirements and lug size. In your scenario the wire is being protected by the breaker so it's fine. 

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## paulengr (Oct 8, 2017)

This makes no sense. So if I have a distribution panel with a 200 A main that means I can’t install any breakers under 200 A? No 15 A breakers? You are looking at the wrong rating.

You are confusing apples and oranges. The disconnect has a short circuit rating, actually two of them, and an ampacity. The short circuit rating means in the event of a fault the disconnect is heavy enough it won’t be ripped apart by the magnetic forces on the components. There is often an interrupting rating too which is lower on some disconnects where it can carry a fault current but would be destroyed if it is opened at that current. Finally the ampacity is how it is rated so that it doesn’t overheat and melt down. The interrupting and withstand ratings will be in kA (thousands of amperes). For a fused disconnect it is usually the fuse rating, typically 100 kA or 300 kA. The ampacity is much lower typically under 1000 A. So in an unfused disconnect the upstream breaker/fuses protect it as far as ampacity. In a fused one ampacity is dependent on the fuses.


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## gpop (May 14, 2018)

iwannawaterski said:


> So you're saying that you could terminate a 200A circuit (assuming you could fit the wire in, which you couldn't) to a 30A dx as long as the voltage is at or below the rating...


Yes as long as the wire fits you are good to go. 

Lets say you did this in real life. A 200 amp breaker will be protecting the wire to the disconnect and the wire can handle 200 amps so that side is good.

Now you fuse to 60 amps and the wire on the load side is rated for 60 amps so that side is good. 

The fuse will blow at 60 amps so the circuit will never be able to go higher than 60 amps unless there is a fault. If the fault is on the line side the breaker will clear the fault before the wire burns. If the fault is on the load side the fuses will clear the fault before the 60 amp wire burns. (always a good idea to label the max size fuse allowed)

I personally would not use a wire rated less than the breaker even if the breaker can be neutered to 70 amps (and labelled). I would either run wire capable of supporting 100 amps or install fuses close to the breaker. 

Now what affect it has on arc fault is something you would have to disgust with a engineer.


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## Mobius87 (May 20, 2019)

iwannawaterski said:


> So you're saying that you could terminate a 200A circuit (assuming you could fit the wire in, which you couldn't) to a 30A dx as long as the voltage is at or below the rating...


How is that any different than coming off of a 200A splitter and terminating into a 30A disconnect. As long as the wire is sized appropriately feeding the disconnect (splitter rule, or sized for the main current), the you're good to go.

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## Mobius87 (May 20, 2019)

Also, the OP has more attitude than a 14 year old girl .

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## iwannawaterski (Dec 17, 2019)

OK guys, I just spoke to the technical support for GE, and I got news for you. You're all wrong! If the disconnect is rated at 60 A, the most you can connect to it is 60A PERIOD!! It doesn't matter what the lugs you're terminating on are rated for. It doesn't matter if the dx is service rated. There is no way the manufacturer will warranty a failure of any sort, much less advise you to connect a circuit rated higher than the rating of the disconnect. This is straight from the manufacturer.

Everybody that is using the tap rule to size down a circuit from a higher amperage to a lower one and terminating on a disconnect that isn't rated at the higher amperage or greater is DOING IT INCORRECTLY according to the manufacturer.

Who has the attitude now Mobius87???


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## VELOCI3 (Aug 15, 2019)

iwannawaterski said:


> OK guys, I just spoke to the technical support for GE, and I got news for you. You're all wrong! If the disconnect is rated at 60 A, the most you can connect to it is 60A PERIOD!! It doesn't matter what the lugs you're terminating on are rated for. It doesn't matter if the dx is service rated. There is no way the manufacturer will warranty a failure of any sort, much less advise you to connect a circuit rated higher than the rating of the disconnect. This is straight from the manufacturer.
> 
> Everybody that is using the tap rule to size down a circuit from a higher amperage to a lower one and terminating on a disconnect that isn't rated at the higher amperage or greater is DOING IT INCORRECTLY according to the manufacturer.
> 
> Who has the attitude now Mobius87???




So GE’s Service rated disconnect that is connected to an unfused utility service is now fake news? I think you might’ve misunderstood the info you’ve received. 


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## Mobius87 (May 20, 2019)

iwannawaterski said:


> OK guys, I just spoke to the technical support for GE, and I got news for you. You're all wrong! If the disconnect is rated at 60 A, the most you can connect to it is 60A PERIOD!! It doesn't matter what the lugs you're terminating on are rated for. It doesn't matter if the dx is service rated. There is no way the manufacturer will warranty a failure of any sort, much less advise you to connect a circuit rated higher than the rating of the disconnect. This is straight from the manufacturer.
> 
> Everybody that is using the tap rule to size down a circuit from a higher amperage to a lower one and terminating on a disconnect that isn't rated at the higher amperage or greater is DOING IT INCORRECTLY according to the manufacturer.
> 
> Who has the attitude now Mobius87???


Clearly still you. Yes, if you have a 60A disconnect you can only connect a 60A LOAD to it (generally speaking)...... but you can FEED the LINE from a a higher amperage feed as long as you follow the appropriate codes. Holy crap, I'm glad I'm not your co-worker. I'm sure you're beloved. 

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## HackWork (Oct 2, 2009)

iwannawaterski said:


> OK guys, I just spoke to the technical support for GE, and I got news for you. You're all wrong! If the disconnect is rated at 60 A, the most you can connect to it is 60A PERIOD!! It doesn't matter what the lugs you're terminating on are rated for. It doesn't matter if the dx is service rated. There is no way the manufacturer will warranty a failure of any sort, much less advise you to connect a circuit rated higher than the rating of the disconnect. This is straight from the manufacturer.
> 
> Everybody that is using the tap rule to size down a circuit from a higher amperage to a lower one and terminating on a disconnect that isn't rated at the higher amperage or greater is DOING IT INCORRECTLY according to the manufacturer.
> 
> Who has the attitude now Mobius87???


This would be a good time to stop posting and walk away.


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## eddy current (Feb 28, 2009)

iwannawaterski said:


> Everybody that is using the tap rule to size down a circuit from a higher amperage to a lower one and terminating on a disconnect that isn't rated at the higher amperage or greater is DOING IT INCORRECTLY according to the manufacturer.


So lets say you have a 400 amp disconnect feeding a 400 amp splitter trough. Off of that splitter trough you have four 80 amp loads so you install four 100 amp fused disconnects following the tap conductor rules for wire size for the feeds to those disconnects.

Are you trying to say that would be incorrect? 

So each one of those disconnects must be 400 amp disconnects? If so, why is there even a tap conductor code?


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## Forge Boyz (Nov 7, 2014)

eddy current said:


> So lets say you have a 400 amp disconnect feeding a 400 amp splitter trough. Off of that splitter trough you have four 80 amp loads so you install four 100 amp fused disconnects following the tap conductor rules for wire size for the feeds to those disconnects.
> 
> Are you trying to say that would be incorrect?
> 
> So each one of those disconnects must be 400 amp disconnects? If so, why is there even a tap conductor code?


I'd like to see the fuse reducers for that.

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## gpop (May 14, 2018)

And this boys and girls is why phoning technical support is a waste of time and forums like this exist. 

Sometimes you guys are aggressive when you post but i never take it to heart as you have probably had to work with a apprentice like this prick all day and your just blowing of some steam.


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## HackWork (Oct 2, 2009)

gpop said:


> And this boys and girls is why phoning technical support is a waste of time and forums like this exist.
> 
> Sometimes you guys are aggressive when you post but i never take it to heart as you have probably had to work with a apprentice like this prick all day and your just blowing of some steam.


I love you.


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## CoolWill (Jan 5, 2019)

iwannawaterski said:


> OK guys, I just spoke to the technical support for GE, and I got news for you. You're all wrong! If the disconnect is rated at 60 A, the most you can connect to it is 60A PERIOD!! It doesn't matter what the lugs you're terminating on are rated for. It doesn't matter if the dx is service rated. There is no way the manufacturer will warranty a failure of any sort, much less advise you to connect a circuit rated higher than the rating of the disconnect. This is straight from the manufacturer.
> 
> Everybody that is using the tap rule to size down a circuit from a higher amperage to a lower one and terminating on a disconnect that isn't rated at the higher amperage or greater is DOING IT INCORRECTLY according to the manufacturer.
> 
> Who has the attitude now Mobius87???


Pudge, why are you hiding behind this **** screen name?


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## micromind (Aug 11, 2007)

240.21
Location in circuit. Overcorrect protection shall be provided in each ungrounded circuit conductor and shall be located at the point where the conductors receive their supply except as specified in 240.21(A) through (G). 

I don't see anything in (A) through (G) that allows a conductor to be protected by a fused disconnect that's more than 25' from the breaker that feeds it.


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## VELOCI3 (Aug 15, 2019)

micromind said:


> 240.21
> Location in circuit. Overcorrect protection shall be provided in each ungrounded circuit conductor and shall be located at the point where the conductors receive their supply except as specified in 240.21(A) through (G).
> 
> I don't see anything in (A) through (G) that allows a conductor to be protected by a fused disconnect that's more than 25' from the breaker that feeds it.




He has a 70 amp breaker at the point of origin. Tap rule doesn’t apply


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## JoeSparky (Mar 25, 2010)

iwannawaterski said:


> OK guys, I just spoke to the technical support for GE, and I got news for you. You're all wrong! If the disconnect is rated at 60 A, the most you can connect to it is 60A PERIOD!! It doesn't matter what the lugs you're terminating on are rated for. It doesn't matter if the dx is service rated. There is no way the manufacturer will warranty a failure of any sort, much less advise you to connect a circuit rated higher than the rating of the disconnect. This is straight from the manufacturer.
> 
> Everybody that is using the tap rule to size down a circuit from a higher amperage to a lower one and terminating on a disconnect that isn't rated at the higher amperage or greater is DOING IT INCORRECTLY according to the manufacturer.
> 
> Who has the attitude now Mobius87???


Sounds like good advice from tech support :no:
Next time I Install a new 200a residential service, I have to call the power company and find out what size transformer and fuse they are connecting to my equipment. If they tell me 400a, I have to use 400a riser, meter socket and loadcenter, but get a 200a main for this loadcenter? :no:


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## CoolWill (Jan 5, 2019)

This Mike Holt's troll account. You can tell by the water ski name. Mike is an avid participant in the gayest sport on planet Earth, barefoot skiing. He's angry that this forum is getting posts.


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## HackWork (Oct 2, 2009)

CoolWill said:


> Pudge, why are you hiding behind this **** screen name?


How dare you?


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## CoolWill (Jan 5, 2019)

HackWork said:


> How dare you?


Very well, thank you.


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## splatz (May 23, 2015)

VELOCI3 said:


> So GE’s Service rated disconnect that is connected to an unfused utility service is now fake news? I think you might’ve misunderstood the info you’ve received.


This is the part I am wondering about, which end of that phone call was the dumbass? 

I would not be surprised if it was the people they have answer the phones at GE. Most of the manufacturers seem to hire big call centers full of Home Depot level help to screen calls for the engineers. They read and interpret what they can find on the manufacturer's web site off to the caller. I guess on a boring day they will interpret it to the best of their abilities and training they received in a three hour seminar at the Sheraton. 

I get dopey answers all the time when I call. Sometimes you can drill through the telephone gatekeepers and get to a grown up but it's tough.


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## JoeSparky (Mar 25, 2010)

Expert said:


> You seem like an expert.


Hacky, you are going to burn through quite a few names this way. I don't know what you did, but you'd be better off sitting this one out on valdes island.
BTW, you are an Expert:wink::brows:


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## JoeSparky (Mar 25, 2010)

Expert said:


> Do I know you?


Yes, we met on a camping trip. if I remember correctly, you were not following social distancing rules at all:surprise:


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## CoolWill (Jan 5, 2019)

I'm getting this rapey vibe.


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## joe-nwt (Mar 28, 2019)

Yes you can terminate a properly installed and protected 70A circuit on a 60A disconnect, at which point the circuit will be protected to 60A. 

Clear enough or do you want some other answer?


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## JoeSparky (Mar 25, 2010)

CoolWill said:


> I'm getting this rapey vibe.


That was quick! I managed to see it all today. 

See you tomorrow Hacky :vs_wave:


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## JoeSparky (Mar 25, 2010)

frq3efeq said:


> You said rape twice.



Welcome back Hacky!

:vs_wave::vs_wave::vs_wave:
:vs_wave::vs_wave:
:vs_wave:


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## Cow (Jan 16, 2008)

Let me see if I can help you understand.

Are you familiar with the tap rules? 

For example, in the ag work we do for potato piling equipment and similar, it is very common to have a main fused disconnect(100, 200, 400 amp, etc) feeding a gutter or similar with multiple 30-60 amp disconnects tapped from that one common feeder. Using your logic, I couldn't install a 60 amp disconnect without a 60 amp OCPD in front of it.

That is why the tap rules exist.


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## eddy current (Feb 28, 2009)

Cow said:


> Let me see if I can help you understand.
> 
> Are you familiar with the tap rules?
> 
> ...


Does the NEC have maximum distances for tap conductors?


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## CoolWill (Jan 5, 2019)

eddy current said:


> Does the NEC have maximum distances for tap conductors?


25 feet inside and unlimited outside.


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## eddy current (Feb 28, 2009)

CoolWill said:


> 25 feet inside and unlimited outside.


Inside and outside the equipment?

Like if you had a 400 amp disconnect feeding a splitter trough and you wanted to tie a 30 amp disconnect off of it, is there a max distance you can run 30 amp wire to feed the 30 amp disconnect from the 400 amp splitter trough?


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## CoolWill (Jan 5, 2019)

eddy current said:


> Inside and outside the equipment?


Inside and outside of buildings.



> Like if you had a 400 amp disconnect feeding a splitter trough and you wanted to tie a 30 amp disconnect off of it, is there a max distance you can run 30 amp wire to feed the 30 amp disconnect from the 400 amp splitter trough?


We couldn't do it with the wire size and amps in your example. The tap conductors have to have an ampacity of at least 1/3 of the feeder. But at any rate, 25 feet is the max distance they could be run inside of a building. I may or may not have installed a couple of 30 foot taps in the past.:shifty:


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## eddy current (Feb 28, 2009)

CoolWill said:


> Inside and outside of buildings.
> 
> 
> 
> We couldn't do it with the wire size and amps in your example. The tap conductors have to have an ampacity of at least 1/3 of the feeder. But at any rate, 25 feet is the max distance they could be run inside of a building. I may or may not have installed a couple of 30 foot taps in the past.:shifty:


We can. CEC 14-100

If the length of the smaller conductor (tap conductor) is less than 3 meters we can. Example, 400 amp disconnect and splitter trough with a tap for a 30 amp disconnect using only 30 amp wire.

If the length of the smaller wire is longer than 3 meters but no more than 7.5 meters, it must be 1/3 the size of the feeder.

Over 7.5 meters we can not use a smaller conductor than the feeder.


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## Easy (Oct 18, 2017)

iwannawaterski said:


> Need some input here from the experienced electricians:
> 
> I have a situation where there is a branch circuit fed by an adjustable breaker that can only dial down to 70A. However, the fused disconnect within the control cabinet that we're re-purposing the circuit for is only rated at 60A. In order to properly use this circuit, I maintain that it needs to be landed in a fused disconnect first, and then fused at 60A before it can be terminated in the control cabinet. Since dx sizes are 30A, 60A, and then to 100A, I say that it should be landed in a 100A dx and fused at 60A. Others are saying that it can land in a 60A dx and fused at 60A. My argument is that the termination points in the 60A dx aren't rated for the 70A that will be available to it.
> 
> Opinions?


If you were to use this logic than a 200 amp panel would only be permitted to have 200 amp circuit breakers and 3/0 copper for all of it's branch circuits. 
The 60 amp fuses are protecting the conductors on the load side of the disco not the ones on the 70 amp breaker. If you had an over current condition the fuses would protect the conductors, the disco and all of its internal parts. 
Don't waist your money on a larger disconnect because someone might decide to put in larger fuses and then you would have issues.


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