Current limiting fuses to protect equipment

[Jraef]

I used to work for a panel builder making lift station panels and they are pretty competitive. Anything to get the price down, even if it's $100. It isn't difficult for a 508 shop to build a 65kaic panel, but it does cost a bit more and the panel might be a bit bigger. The cheaper shops would prefer to load it up with the cheapest parts available and make it up later in change orders.

This is easily combated by:

inform your buyers that from here on out, they need to require an SCCR that meets or exceeds the AFC!

It certainly isn't hard if done before the panel is built, but it is quite expensive to upgrade an existing install to 65kaic. UL could also do a field inspection to "verify" listing is valid, but be prepared to pay $$$$ and find other things wrong that they will want to see fixed.

I though that was what I was saying, but I guess it was misinterpreted. It's NOT AT ALL DIFFICULT to attain a 65kA SCCR value on most things, it just takes some minimal effort in selecting components. The "5kA" label is the "courtesy" listing that UL allows someone to apply without testing or using listed combinations; i.e. the lowest default level if you don't try.

 

[petersonra]

One of the problems with people who make a lot of these standardized control panels is they want to be able to substitute parts from different manufacturers based on what is the cheapest part available right this second. This is not a big deal for current limiting fuses, since UL considers a Class J, CC, etc fuse made by anyone as equivalent, but it can make a difference with other parts. For instance some contactors have been series tested with Class CC fuses, while other with Class J fuses, and some with both. But if you want to use whatever is cheapest right now you have to accommodate all situations, and it is just a lot simpler to use the 5kA rating so you don't have to figure out all the permutations..

 

[jim dungar]

As it has been mentioned, buyers should be aware of the required SCCR and put it in their spec.

What is the normal EC
procedure for customer furnished equipment that is not compliant?

 

[don_resqcapt19]

As it has been mentioned, buyers should be aware of the required SCCR and put it in their spec.

What is the normal EC
procedure for customer furnished equipment that is not compliant?

In many cases it is just that the mechanical engineers for the project need to talk with the electrical engineers for the project.

Often the EC will have to fight for a change order to fix the issue...or get the AHJ to require the owner to supply equipment suitable for the electrical system.

 

[petersonra]

What is the normal EC
procedure for customer furnished equipment that is not compliant?

I don't understand why it is a problem for the EC at all. If the customer supplied equipment is not suitable, it gets turned over to the customer to deal with. I know contractors like to meddle in these kind of things thinking they can make a buck, but it is not something the contractor should want to get involved in. just tell the customer it is unsuitable and why, in writing, and let them deal with their problem.

 

[topgone]

In many cases it is just that the mechanical engineers for the project need to talk with the electrical engineers for the project.

Often the EC will have to fight for a change order to fix the issue...or get the AHJ to require the owner to supply equipment suitable for the electrical system.

In my experience, it is the EC forcing my company (in my other life) to accept their installations (I saw the specs of their underrated contactors in series with a higher rated disconnecting device). Perhaps they wanted easy money, that's all!

 

[don_resqcapt19]

In my experience, it is the EC forcing my company (in my other life) to accept their installations (I saw the specs of their underrated contactors in series with a higher rated disconnecting device). Perhaps they wanted easy money, that's all!

If we are talking about manufactured equipment supplied by others, I don't see how any of that is the problem of the EC.

 

[ptonsparky]

If we are talking about manufactured equipment supplied by others, I don't see how any of that is the problem of the EC.

It is if he refuses to connect it. Big Time.

 

[don_resqcapt19]

It is if he refuses to connect it. Big Time.

Actually it is a big problem for the EC if he does connect it to a circuit that has more available fault current than the SCCR of the equipment. Not connecting it is the correct action by the EC.

 

[ptonsparky]

Actually it is a big problem for the EC if he does connect it to a circuit that has more available fault current than the SCCR of the equipment. Not connecting it is the correct action by the EC.

Screwed either way.

 

[petersonra]

In my experience, it is the EC forcing my company (in my other life) to accept their installations (I saw the specs of their underrated contactors in series with a higher rated disconnecting device). Perhaps they wanted easy money, that's all!

That could be a perfectly legal and safe installation.