Copper Pipes for Fuses

Is this ever correct? It appeared to be protected down upstream by a 70 AMP sub panel breaker.

No lolol never

Are you serious?

No, recently been seeing it way too often.

Not proper in this case they need proper size fuses to protect what ever is being fed .

Is this ever correct? Not in a fuse holder like this . They can some times ( Very seldom ) be used in a Isolation switch that has proper protection upstream .


Ok…I think you mean “upstream” by a 70A breaker. Now in terms of the use of the CU pipe…no never permitted. However, the concept is very similar in using a pull out disconnect downstream of your upstream remote distribution panel.

However, its not the same because CU piping is not evaluated for this application and the device they are placed into has not been evaluated for such a CU pipe either.

But just as a learning lesson…it is still theoretically the same as having a downstream “pull out” disconnect…theoretically speaking of course in your case.

I think 1/2" is rated for 175 amps and 3/4" is around 250 amps. Then you have to consider derating if they are Type M and not Type L.


Just in case…the previous post is sarcasm at it’s best/worst.

I Hear Ya…the problem is I have heard people try to tell people it is fine…since it is copper.

Hey Wait…Maybe it is OK if it’s CU and not OK if it’s AL…not sure as I think the experts who write articles on the perils of AL Conductors may consider it…

Now THAT my friend is Sarcasm !

Like the photo’s that Roy posted these types of things are manufactured and used in some specific installations. I don’t see a problem if they’re listed and used for example in a fused disconnect where you did not want fuse protection and only needed a disconnecting means.

Here’s a NYC fire alarm fuse cut-out power panel.

Me Either…If Listed for the use;)

In N.Y., is there a triple lug on the line side of the first disconnect to feed the FCO and the fire pump? Or is it a different set up?


Usually there is a “tap” ahead of the service disconnect to feed the fire alarm system and the fire pump. I used tap in quotes because there are technically no taps when your dealing with service entrance conductors.