Section 215.10 Exception 2

[Grouch1980]

Hi,
Can someone please help me understand the exception from the title?:

215.10 exception 2: The provisions of this section shall not apply if ground-fault protection of equipment is provided on the supply side of the feeder and on the load side of any transformer supplying the feeder.

It's the second part with the transformer that throws me off.

Do both conditions of this exception have to be true in order to use this exception? The way I interpret it is: you don't need GFP on a feeder if further upstream of that feeder (whether the service or another feeder) already has GFP AND that GFP that's upstream is ALSO on the load side of a transformer. Is this correct? Or is it one condition or the other that can trigger this exception?

 

[LarryFine]

Do both conditions of this exception have to be true in order to use this exception?

The "and" tells me it's both.

 

[Grouch1980]

The "and" tells me it's both.

I agree as well. However... this interpretation confuses me. So if you have GFP upstream of a feeder, say at the service one level above the feeder, you STILL need GFP at the feeder since we're NOT on the load side of a transformer?

 

[infinity]

I agree as well. However... this interpretation confuses me. So if you have GFP upstream of a feeder, say at the service one level above the feeder, you STILL need GFP at the feeder since we're NOT on the load side of a transformer?

No if there is a transformer in the feeder then that negates the GFPE protection on the primary side of the transformer.

So GFPE>transformer>feeder then GFPE is required for the feeder on the secondary side.

 

[Buck Parrish]

I agree as well. However... this interpretation confuses me. So if you have GFP upstream of a feeder, say at the service one level above the feeder, you STILL need GFP at the feeder since we're NOT on the load side of a transformer?

It's my understanding .Depending on the transformer. The line side gfci may not work on the load side.

 

[LarryFine]

An isolated secondary is an SDS, which is why new electrode connections are needed.

Any fault or shock current is confined to the secondary, and will not affect the primary.

 

[Grouch1980]

No if there is a transformer in the feeder then that negates the GFPE protection on the primary side of the transformer.

So GFPE>transformer>feeder then GFPE is required for the feeder on the secondary side.

That I get.

For some reason, I'm not reading that when I read the exception.

 

[augie47]

My read.................
Each feeder rated 1000 amps of more installed on a solidly grounded wye system of more than 150 volts......................................................

Exception 2 says that IF you have 1000 amp feeder in say a 3000 amp switchboard and the 3000 amp main has GF protection then the 1000 amo feeder does not have to have it since the 3000 is providing the required protection.
Likewise if the load side of a transformer has GF protection say on a 3000 amp secondary panel, you do not need the 1000 amp feeders to have protection also

 

[Grouch1980]

Got it.

Maybe it's me, but for starters, that 'and' in the exception should be an 'or'. The 'and' is implying that the transformer HAS to be present for this entire exception to be valid.

 

[augie47]

Got it.

Maybe it's me, but for starters, that 'and' in the exception should be an 'or'. The 'and' is implying that the transformer HAS to be present for this entire exception to be valid.

I would agree with that.

 

[don_resqcapt19]

Got it.

Maybe it's me, but for starters, that 'and' in the exception should be an 'or'. The 'and' is implying that the transformer HAS to be present for this entire exception to be valid.

You can try to fix that...the system is open for the submission of Public Inputs to make changes for the 2026 code
www.nfpa.org/70 and select "Submit a Public Input for the Next Edition"

 

[Grouch1980]

Awesome! Sure, I'll work on submitting that.

 

[Grouch1980]

Thanks everyone for the help!

 

[JoeStillman]

Be careful how you propose to change it. If it said "or" you could conceivably put the GFCI upstream of the transformer and that wouldn't work because you have a separately derived system. The transformer blocks the path back to the GFCI sensor for any ground faults.