(2005 code) 240.21(C)(1) states that "multiphase (other than delta-delta, 3-wire) transformer secondary conductors are not considered to be protected by the primary overcurrent protective device."
450.3(B) shows that you do not need secondary overcurrent protection for transformers if the primary is no larger than 125% of the transformer rating.
Does 450.3(B) only apply to non-multiphase transformers? 450 doesn't specify the table to apply to any specific type of transformer (except <600V).
If I have a transformer in room 'A', and I am serving panel(s) in another room 'B' in another part of the building, do I need to provide disconnects at the transformer, or is the MCB suficient of the served panels provided I do not exceed 125% on the transformer's primary?
Everyone seems to give conflicting answers on this.
450.3(B) shows that you do not need secondary overcurrent protection for transformers if the primary is no larger than 125% of the transformer rating.
Does 450.3(B) only apply to non-multiphase transformers? 450 doesn't specify the table to apply to any specific type of transformer (except <600V).
If I have a transformer in room 'A', and I am serving panel(s) in another room 'B' in another part of the building, do I need to provide disconnects at the transformer, or is the MCB suficient of the served panels provided I do not exceed 125% on the transformer's primary?
Everyone seems to give conflicting answers on this.