New electrical service

[rotortuner]

Just want to run something by you guys. I have a 60x68 building and am going with a new dedicated service. The meter will be close to on the of corners. To minimize runs to outlets etc. My plan has been to use a 320-400 meter base with twin 200 amp disconnect breakers. Then on two adjacent walls have a 200 amp distribution panel, then a 100 amp sub panel on the other two walls. essentially I woud have a panel either, 100 or 200 amp on each wall. Overkill?

Electrical supply house is trying to talk me out of the meter base disconnect because its so expensive, but I believe I need this since my panels are a ways back into the building an not on the back of the wall where the meter is located. One of the panels is going to be on the back wall about 50ft away. thoughts?

 

[wyliesdiesels]

There is no NEC code for maximum length of unfused service entrance wire so need to check with your local AHJ.

Have you thought of doing a meter main with multiple disconnects and then brqnch off to your panels from there?

Why are you going with 400a(320a continuous) service? Thats a lot of power.

Do you really need all that power?

What will your loads be?

Electric heat, AC, large motors, dryer, compressor, etc??

How many people at the same time?

Have you done a load calc?

Maybe drop it down to 200a...

 

[PT Doc]

There is no NEC code for maximum length of unfused service entrance wire so need to check with your local AHJ.

Have you thought of doing a meter main with multiple disconnects and then brqnch off to your panels from there?

Why are you going with 400a(320a continuous) service? Thats a lot of power.

Do you really need all that power?

What will your loads be?

Electric heat, AC, large motors, dryer, compressor, etc??

How many people at the same time?

Have you done a load calc?

Maybe drop it down to 200a...

I agree on a smaller panel size unless you have a tremendous amount of machinery that will be running concurrently.

Our builder put every room on separate circuits and I have 7 240 50a breakers. My service is 400a. And likely I have more expansion capacity based on load calls.

 

[rotortuner]

There is no NEC code for maximum length of unfused service entrance wire so need to check with your local AHJ.

Have you thought of doing a meter main with multiple disconnects and then brqnch off to your panels from there?

Why are you going with 400a(320a continuous) service? Thats a lot of power.

Do you really need all that power?

What will your loads be?

Electric heat, AC, large motors, dryer, compressor, etc??

How many people at the same time?

Have you done a load calc?

Maybe drop it down to 200a...

5 ton heat pump, on demand hot water, air compressor, those could potentially all run at the same time. LRA on the heat pump is like 150 amps alone. Are you talking a base with a couple separate disconnects in different enclosures or disconnects as part of the meter base? What I'm looking to buy is a meter base with 2 200 amp breakers in it. then sink ground rods from that then run 4 wires to each of the 200 panels as sub panels. then I don't believe I need to do ground rods in those sub panels.

 

[mike93lx]

5 ton heat pump, on demand hot water, air compressor, those could potentially all run at the same time. LRA on the heat pump is like 150 amps alone. Are you talking a base with a couple separate disconnects in different enclosures or disconnects as part of the meter base? What I'm looking to buy is a meter base with 2 200 amp breakers in it. then sink ground rods from that then run 4 wires to each of the 200 panels as sub panels. then I don't believe I need to do ground rods in those sub panels.

You are going to have to do a real load calc if you want a transformer and feeder that will actually support 320a

 

[rotortuner]

My service provider did that here. they own the service all the way to meter base and install the in ground cable, they are using 350mcm from the vault. I own down stream of the meter base. I'm using 4/0.

 

[Norcal]

5 ton heat pump, on demand hot water, air compressor, those could potentially all run at the same time. LRA on the heat pump is like 150 amps alone. Are you talking a base with a couple separate disconnects in different enclosures or disconnects as part of the meter base? What I'm looking to buy is a meter base with 2 200 amp breakers in it. then sink ground rods from that then run 4 wires to each of the 200 panels as sub panels. then I don't believe I need to do ground rods in those sub panels.

You do not size a service based on the LRA. If this is a new build then a UFER should be used rather then ground rods, sub panels in the same structure do not require rods. There is more but phones are not the best way to post comments.

 

[TRWham]

1. If someone who makes money selling you something is trying to talk you out of it, you might want to listen.
2. Little wire costs a lot less than big wire, not to mention the cost of the additional panels, so I think you will spend more money distributing all these panels than you would just running all the circuits to one location.
3. Your eyes are bigger than your stomach with regard to power needs.
4. I second the Ufer ground. Your AHJ will probably require it anyway.

 

[alfredeneuman]

On demand water heaters require some heavy circuits.

It's not unusual to have a 36KW heater that draws 150A @ 240V

 

[Dagny]

I have to agree seems like a lot of lectrical for the size of the building.

 

[sberry]

I would get rid of the demand heater too. I wouldn't have a problem with a modest sub or 2 to reduce long wire runs to part of the building.

 

[mike93lx]

On demand water heaters require some heavy circuits.

It's not unusual to have a 36KW heater that draws 150A @ 240V

A 36kw heater will always draw 150a (at 240v),assuming it is running full tilt.

 

[alfredeneuman]

A 36kw heater will always draw 150a (at 240v),assuming it is running full tilt.

They're either on full tilt or they are off. No in between

 

[mike93lx]

They're either on full tilt or they are off. No in between

You saying it isn't unusual was what i addressed. Every single 36kw heater draws 150a, otherwise it isn't a 36kw heater.

 

[alfredeneuman]

How about this:
It's not unusual for a person to own a 36KW on demand.......

 

[AP514]

On demand Gas is the way to go......Just saying

 

[jim111]

Do a proper load calculation to determine your service need. If you do indeed need 320/400 then the meter/main route will be your cleanest install

 

[mike93lx]

On demand Gas is the way to go......Just saying

I don't think anyone would ever argue that or choose electric if gas was available.

 

[nsula_country]

I would get rid of the demand heater too. I wouldn't have a problem with a modest sub or 2 to reduce long wire runs to part of the building.

That is just bad advice. Period.

CT

 

[nsula_country]

On demand Gas is the way to go......Just saying

If one has NG gas service available... Some of us don't and don't want to deal with LP.

CT

 

[nsula_country]

They're either on full tilt or they are off. No in between

Cannot be more wrong... They modulate. Most use PWM to throttle the elements. A 36 kw will have 4 elements. Not all 4 are on at low flow rates.

FYI, I have a 320 amp resi service at the house and two 27kw ECO-Smarts and have had 0 issues in 6 years. Love them.

I don't know why there is so much hatred for on-demand tank less electric. They only use electricity when in use. They modulate, so they only use AS MUCH electricity as required. They are about the same price as a 50 gal electric tank heater and can be mounted of a wall and only 4" deep...

CT

 

[alfredeneuman]

Thanks for the info.....I stand corrected.

You still have to figure in the 150A figure when you do load calcs though.

 

[nsula_country]

Thanks for the info.....I stand corrected.

You still have to figure in the 150A figure when you do load calcs though.

This is true. Two 27kw units pushed me over the 200 amp line.

CT

 

[rotortuner]

Thanks for all the advice, I know with a 5 ton heat pump and an on demand I will be over 200 for sure and I want room to grow in the future. I'm going to research the 320 meter main and then possible 100 amp sub panels to reduce the wire runs. Thanks for the help.

 

[Bert_]

If you run pipe from the meter to your service panel(s) under the slab, then you can go anywhere in the building you want. The wire would not be considered in the building until it emerged from the slab.

If you make the inside panels the first disconnect then they need to be together, Service disconnects in a building are required to be grouped.