notmyspace
Member
- Location
- Maryland
Could someone interpret this for me? I am slightly confused here.
I have a site that has an existing 45KVA transformer 600V 3 phase 208Y/120V rated at 29A primary and 83A on the secondary
There is an existing 60A disconnect with (4) #6 and (1) #8gnd connected to the transformer. On the secondary side, we have a 100A breaker panel connected to the transformer with a (4) #1 and (1) #6 gnd. The total load on the secondary side is 63.83A that is calculated with 125%.
Distance transformer to the breaker panel is around 10ft.
Based on the article 450.3(b) and 240, do I cover the overprotection to the transformer and conductor?
I saw article 450, there are two methods
Method 1: Primary protection only ? set no more than 125% primary current rating, and does not required secondary protection
Method 2: Secondary Protection set no more than 125% provided the primary current protection set less than 250%.
So, given those requirement, I should have less than 250% primary current protection and slightly less than 125% (around 120.5%) right?
thanks
I have a site that has an existing 45KVA transformer 600V 3 phase 208Y/120V rated at 29A primary and 83A on the secondary
There is an existing 60A disconnect with (4) #6 and (1) #8gnd connected to the transformer. On the secondary side, we have a 100A breaker panel connected to the transformer with a (4) #1 and (1) #6 gnd. The total load on the secondary side is 63.83A that is calculated with 125%.
Distance transformer to the breaker panel is around 10ft.
Based on the article 450.3(b) and 240, do I cover the overprotection to the transformer and conductor?
I saw article 450, there are two methods
Method 1: Primary protection only ? set no more than 125% primary current rating, and does not required secondary protection
Method 2: Secondary Protection set no more than 125% provided the primary current protection set less than 250%.
So, given those requirement, I should have less than 250% primary current protection and slightly less than 125% (around 120.5%) right?
thanks