equipmen grounding conductor for transformers primary and secondary 2008 nec

[grumpy11]

kicking this around with some other people as a rule an egc is run both for primary and secondary conductors.

but according to article 250.118

if emt was installed both from primary and secondary. i dont think you need it

if flex was installed for both and the distance is less then 6ft i still dont think you need it .

now in both installations i would use either bonding bushing or bonding locknuts

any thoughts.

 

[augie47]

You need to re-think your flex I believe.
Notice in 250.118 for flex there are multiple limitations that apply. The 5 ft is only one.

Since, in most cases, flex would not be a suitable grounding means there is little use in adding a grounding bushing.

 

[don_resqcapt19]

Don't forget that the secondary will also need a GEC.

 

[kwired]

Don't forget that the secondary will also need a GEC.

Exactly. Metal raceways are acceptable equipment grounding conductors, they are not acceptable grounding electrode conductors though.

You can have a system that has no "wire" equipment grounding conductors but it will still require a "wire" grounding electrode conductor.

 

[jwelectric]

Items outlined in 250.118 are Equipment grounding conductors.

The conductor from the secondary to the first disconnecting means is a Supply Side Bonding Jumper and is sized by 250.66 and it can’t be any type of flexible raceway

(2) Supply-Side Bonding Jumper. If the source of a separately derived system and the first disconnecting means are located in separate enclosures, a supply-side bonding jumper shall be installed with the circuit conductors from the source enclosure to the first disconnecting means. A supply-side bonding jumper shall not be required to be larger than the derived ungrounded conductors. The supply-side bonding jumper shall be permitted to be of nonflexible metal raceway type or of the wire or bus type as follows

Came back to edit as I read the title of 2008 and this quote is from the 2011

 

[grumpy11]

we are just talking about equipment grounding conductor.

article 250.118

we know that emt will make a good effective ground fault

so if you have emt connected to transformer no egc by code is required.

since we are talking about transformers being protected by more then 20 amps. and installed in flex {greenfield}

then yes an egc is required

 

[infinity]

we are just talking about equipment grounding conductor.

article 250.118

we know that emt will make a good effective ground fault

so if you have emt connected to transformer no egc by code is required.

since we are talking about transformers being protected by more then 20 amps. and installed in flex {greenfield}

then yes an egc is required

This is true on the supply side of the transformer. On the secondary side you need to have what Mike posted.

The supply-side bonding jumper shall be permitted to be of nonflexible metal raceway type or of the wire or bus type

 

[grumpy11]

ok so in flex yes emt no but why 250.66 its an egc not the x/o bonding jumper so 250.122 should apply

 

[jwelectric]

ok so in flex yes emt no but why 250.66 its an egc not the x/o bonding jumper so 250.122 should apply

In order to use 250.122 there must be an overcurrent device ahead of it. The secondary side of the transformer between the secondary connection to the first disconnecting means does not have an overcurrent device.

The supply side bonding jumper of the 2011 cycle or Equipment bonding jumper 2008 cycle is not an equipment grounding conductor.