• Welcome to the new and improved Building Code Forum. We appreciate you being here and hope that you are getting the information that you need concerning all codes of the building trades. This is a free forum to the public due to the generosity of the Sawhorses, Corporate Supporters and Supporters who have upgraded their accounts. If you would like to have improved access to the forum please upgrade to Sawhorse by first logging in then clicking here: Upgrades

90°C Wire for Feeder

jar546

Forum Coordinator
Joined
Oct 16, 2009
Messages
11,028
Location
Somewhere Too Hot & Humid
So here is the scenario. Would you allow this setup?

An 800A MDP (with service disconnect) has to feed a panelboard with a total load of 400A which includes continuous and non-continuous loads. The breaker in the MCP has 75°C terminals as expected and so do the lugs in the panelboard it will feed. Due to that fact they have to run 600MCM copper wire.

The problem is that this is a 90' run and the electrician wants to save some money and use up some 500MCM left over from a previous job. The ECs plan is to come out of the MDP with the 600MCM and within 2', enter a junction box where he will have 90°C rated pressure connectors, then he wants to do the balance of the run with 500MCM to another junction box within 2' of the panelboard where he will again have 90°C pressure connectors and convert back to the 600MCM that will then connect into the panelboard. The EC will then have only 10' of 600MCM and 80' of 500MCM.
 
Last edited:
What’s a MCP?

Breakers are tested for listing with a certain length of full size conductor.
As long as the 2’ of 600 is equal to or greater than the testing length, I say compliant.
 
Top