NEC 450.4(A)

Status
Not open for further replies.
H

hhsting

Senior Member
Location
Glen bunie, md, us
Occupation
Junior plan reviewer
I have auto transformer going from supply side 208V single phase to load side 240V single phase, 5kVA. Load drawn is 16 amps by kitchen cooking appliance. On the 240V side outside of the auto transformer I have 30 amps disconnect fused at 20 amps then going to load.

I am confused by what NEC 450.5(A) says at the end "an overcurrent device shall not be installed in series with the shunt winding of the autotransformer between Points A and B as shown in Figure 450.4(A)". So does that mean the secondary side 20 amps fused disco is not acceptable?
 
hhsting said:
I have auto transformer going from supply side 208V single phase to load side 240V single phase, 5kVA. Load drawn is 16 amps by kitchen cooking appliance. On the 240V side outside of the auto transformer I have 30 amps disconnect fused at 20 amps then going to load.

I am confused by what NEC 450.5(A) says at the end "an overcurrent device shall not be installed in series with the shunt winding of the autotransformer between Points A and B as shown in Figure 450.4(A)". So does that mean the secondary side 20 amps fused disco is not acceptable?
Click to expand...

The 20a fused disconnect on the secondary it fine.

It sounds to me like you may have a Buck/Boost Transformer.

Regardless, it's just telling you where "Not" to place an overcurrent device.

Your overcurrent devices need to be installed on the input and output leads.

JAP>
 
Status
Not open for further replies.
Top