# How to bring two mastheads into one meter can? Gutter?



## Elec Tricks (Nov 17, 2018)

I will be installing a commercial 3 phase 400 amp electric service and I am considering using 2 sets of parralleled 4/0 XHHW instead of 700 kmil XHHW or 500 kmil THHW. To avoid having to derate the 8 conductors in one masthead I want to use two mastheads, but I am not sure how to combine them into the one opening in the Milbank U2594-X 320A 3P OH/UG meter socket. If i put a gutter just above the meter socket and just use it as a pass through for the two mastheads to pass their conductors into the single hub of the meter socket, would some nit picking inspector claim I need to derate the 8 conductors going through a connector and and hub or make me splice each of the two paralleled conductors into the full 400 amp size conductor to feed into the meter socket? arghh 

Its there some other method of doing this?


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## micromind (Aug 11, 2007)

You'll need to get the PUCO specs, after it's done, they own it so they dictate the installation. 

Well, around here anyway.


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## Elec Tricks (Nov 17, 2018)

Yes, I will run it by the POCO's design engineers. Here the utility owns the service drop to the splice with the service entrance conductor and the property owner has everything from the splice downward.in an overhead service.. But the Utility won't energize the service if they don't like how the service is done.


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## mofos be cray (Nov 14, 2016)

Buy a meter which is intended to have two pieces of pipe?


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## joe-nwt (Mar 28, 2019)

Many utilities will not allow any access to unmetered conductors. We aren't even allowed an LB here, much less a gutter.


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## CMP (Oct 30, 2019)

For a 400A service, use a 400A 3Φ CT cabinet and meter, and install as many masts as you want.

Trying to trick 2 masts into a 320A, "thru the meter enclosure" designed for a single conduit entrance, is just not going to fly well.

Or man up and install a mast with 500 Kmil, as it was designed for.

That's likely what your service planner will tell you, they want to see.


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## Southeast Power (Jan 18, 2009)

Elec Tricks said:


> I will be installing a commercial 3 phase 400 amp electric service and I am considering using 2 sets of parralleled 4/0 XHHW instead of 700 kmil XHHW or 500 kmil THHW. To avoid having to derate the 8 conductors in one masthead I want to use two mastheads, but I am not sure how to combine them into the one opening in the Milbank U2594-X 320A 3P OH/UG meter socket. If i put a gutter just above the meter socket and just use it as a pass through for the two mastheads to pass their conductors into the single hub of the meter socket, would some nit picking inspector claim I need to derate the 8 conductors going through a connector and and hub or make me splice each of the two paralleled conductors into the full 400 amp size conductor to feed into the meter socket? arghh
> 
> Its there some other method of doing this?


Use 8- 300 XHHW AL in 4" conduit. One Hub.


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## kb1jb1 (Nov 11, 2017)

I still cannot get it that the utility allows the 320 amp meter for 2 - 200 amp panels. What's next, using 2/0 THHN for a 200 amp commercial service?


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## joe-nwt (Mar 28, 2019)

kb1jb1 said:


> I still cannot get it that the utility allows the 320 amp meter for 2 - 200 amp panels. What's next, using 2/0 THHN for a 200 amp commercial service?


I still cannot get it that the utility dictates code.


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## SWDweller (Dec 9, 2020)

I went and looked at the product mentioned. It sure does not look like parallel would work for very well. The pic I saw overhead did not look very easy either. 
Where I live cave man electric has a schedule of allowed equipment. Does yours?

As for the weather head area make the tails long enough so they can be brought together easily. 
Place the point of attachment on the conduit closer to the utility line.

You could put a gutter up like you said but that to me is more labor and money for you. Land in the gutter, and then down to the meter socket.


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## oldsparky52 (Feb 25, 2020)

...


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## oldsparky52 (Feb 25, 2020)

What is the actual calculated load for the building? 

One 400-amp panel or two 200-amp panels?


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## Southeast Power (Jan 18, 2009)

kb1jb1 said:


> I still cannot get it that the utility allows the 320 amp meter for 2 - 200 amp panels. What's next, using 2/0 THHN for a 200 amp commercial service?


The meter is rated for 320 continuous load.
We use them all of the time for 400 amp services.


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## kb1jb1 (Nov 11, 2017)

Southeast Power said:


> The meter is rated for 320 continuous load.
> We use them all of the time for 400 amp services.


But are you selling a 320 amp service or a 400 amp service? As I said about 2/0, it is rated for 195 amps can we use it for a 200 amp three phase service?


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## oldsparky52 (Feb 25, 2020)

kb1jb1 said:


> But are you selling a 320 amp service or a 400 amp service? As I said about 2/0, it is rated for 195 amps can we use it for a 200 amp three phase service?


What is the thought process that allows you to use 2/0 at 90ºC?


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## Elec Tricks (Nov 17, 2018)

CMP said:


> Or man up and install a mast with 500 Kmil, as it was designed for.


Yes, sometimes the obvious solution is the best solution. 
Thx for the obvious!


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## Elec Tricks (Nov 17, 2018)

oldsparky52 said:


> What is the actual calculated load for the building?


That is a simple question with a complicated answer that I will possibly start another thread on. 

This is a two storied building of artist/craftsman studios that got built out over years. The ground floor has a working 200 amp 3 phase 240/120 service. The previous electrician planned and built out a 200 amp single phase 240/120 service for the second floor thinking that the owner would get a second address for the second floor. The POCO said NO!, One building one electric service. Not my work then, but my work now.

For a few years the second floor has been temporarily fed from the downstairs service, but now potters want to move in with 50 amp 240v kiln or kilns. The next step up from a 200 amp 3 phase meter is a 320/400 amp meter socket, to feed a pair of 200 amp circuit breaker enclousres to feed the first and second floor 200 amp panels.

Tenants often turn over every few years. The stone sculpture with the 3 phase 30 amp 240v air compressor took the compressor with her when she left. The 30 amp CNC plasma Cutter doesn't get used on a regular basis Most tenants have other day jobs, so they in their shop at random hours. Diversified loads. I believe NEC still uses 1 to 3 VA / Square foot for lighting, but everyone is switching to LED lighting which uses far less.

I have a spreadsheet with a line for each of the 16 studio spaces and 3 bathrooms, and depending on the scenario of what type tenant is in each space and working at the same time I can have a wide wide range of calculated loads. 

So what is the ACTUAL calculated load? I know it is more than the 200 amp 3 phase 240v/120v electric service at present.

What do other people do in this situation???


. 







This is an existing commericial building with 16 artsit/craftsman studios and an existing 200 amp 3 phase 240v/120v service. Owner wants to install 50 amp 240v kiln, so we want to upgrade the service


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## oldsparky52 (Feb 25, 2020)

Elec Tricks said:


> What do other people do in this situation???


I would consider telling the owner he needs to pay for an EE to put together a stamped drawing for permitting.


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## Elec Tricks (Nov 17, 2018)

Yes, I agree that is the proper way to do things. 

And If I did, the EE would take my spreadsheet of the 16 studio's and 3 bathrooms and the possible scenario's for tenant's electric use and do some sort of diversity derating of max loads. 

But stepping back a bit, this all comes down to what size service conductors. The meter can only takes up to 600 kmil conductors. So either 600 Cu at 420 amps, 500 Cu at 380 amps, 600 Al at 340 amps or 500 Al at 310 amps. Going from 500 Alum to 600 Alum cost around $40 extra. Moving up to 500 Cu costs $900 more. 

The existing 200 amp service was working for years before the idea of a potter with a 50 amp 240v kiln wanted to move in. 

It seems the 340 amp 600 Al is a good choice, and I don't believe the cost of a EE and stamped drawings would add much value.

I will present all this to the owner, and they typically agree with my recommendations.
.


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## oldsparky52 (Feb 25, 2020)

Elec Tricks said:


> It seems the 340 amp 600 Al is a good choice,
> 
> 
> .


I agree, for a 350-amp service with load calculations at or below 340-amps.

Now, if you can document that the meter is rated for use with 90C terminations, then that would change things (I think) to a 400-amp service with 385-amp or less calculated load.


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## Elec Tricks (Nov 17, 2018)

oldsparky52 said:


> Now, if you can document that the meter is rated for use with 90C terminations, then that would change things (I think) to a 400-amp service with 385-amp or less calculated load.


I was looking at the Milbank catalog as you were writing. I believe it comes down to the K3441 lugs as the weakest link in that chain, and I can't tell what the temperature rating is from there. I assume 75C, and keep that extra 45 amps gained from the 90C rating in mind as a sort of a short term cushion. But I will ask on the Milbank Forum and send a message to the two Milbank reps that Cowboy mentioned

Thanks


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## CMP (Oct 30, 2019)

Elec Tricks said:


> Yes, sometimes the obvious solution is the best solution.
> Thx for the obvious!


And for the not so obvious. What would you tell the owner next spring, if he asked about the possibility of installing a couple vehicle chargers next to the building, and they want to add a second kiln for more throughput, or somebody needs a compressor installed?

A CT meter and tap box could cover for that, or you could tell him that the whole shebang needs to be replaced again.

I've see it happen more than once, people are shortsighted when you have their wallet open. I've also heard from customers who said how smart you are when 6 months after you installed their service and equipment, they ask about adding some additional equipment, when they swore at the time of installation that they will never need anything else.

16 tenant spaces on two floors equates to a lot of variables, versus one occupier per service.


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## mofos be cray (Nov 14, 2016)

Have you asked the poco for historical data on power usage? Might find there's more capacity than thought.


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## Elec Tricks (Nov 17, 2018)

mofos be cray said:


> Have you asked the poco for historical data on power usage? Might find there's more capacity than thought.


Duh, Thanks!
I actually have a folder with old billing information for 10 months which includes KW as well as kWh amounts. 14-21 KW during various months. That implies that a simple 100 amp service would work. I am not sure how they calculate their KW demand charge. It may be averaged over 15 minutes or something, so it wouldn't reflect short term spikes. 

So yes asking the Utility for more historical detail, and an explanation of how billing of KW demand charge is calculated would be the next step.

Looks like there may be lots of capacity for more kilns and vehicle charging stations if I do the upgrade.


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## Elec Tricks (Nov 17, 2018)

CMP said:


> What would you tell the owner next spring, if he asked about the possibility of installing a couple vehicle chargers next to the building


Your comment stuck with me for a few days. So 10% of the money I saved on using Aluminum versus copper I spent on a 200 amp main breaker 8 space panel with feed through lugs instead of the simple 200 amp breaker enclosure. This will allow me to add circuits on the outside of the building in a very low cost way. So yes, I believe the client will appreciate the option to add new loads in the parking lot.

thank you


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## CMP (Oct 30, 2019)

Do keep in mind that all of your service disconnects need to be grouped together.


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## kb1jb1 (Nov 11, 2017)

joe-nwt said:


> I still cannot get it that the utility dictates code.


Here the utility supplies the meter and their meters only go up to 300 amps. After that you need to go with CTs.


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## kb1jb1 (Nov 11, 2017)

oldsparky52 said:


> What is the thought process that allows you to use 2/0 at 90ºC?


Here we can use 2/0 cu for 200 amp residential but 3/0 cu for commercial. 2/0 is good for 195 amps at 90C round up to 200 amp. 175 amps at 75C. Using the same logic 80% of 200 is 160 amps so the 2/0 would be good for 200 amps. 
I remember from a code class the question was what feeders would be used for a 1200 amp service. Everybody said 3 sets of 500 kcmls CU. The instructor said yes and no. You should not sell it as a 1200 amp service because it actually is only 1140 amps and you cannot round up.


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## Elec Tricks (Nov 17, 2018)

CMP said:


> Do keep in mind that all of your service disconnects need to be grouped together.


Yes I agree. 
The 400 amp meter above a gutter with taps feeding a 200 amp breaker enclosure on one side and a 200 amp 8 space main breaker electrical panel on the other side of the meter can.


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## oldsparky52 (Feb 25, 2020)

kb1jb1 said:


> Here we can use 2/0 cu for 200 amp residential but 3/0 cu for commercial. 2/0 is good for 195 amps at 90C round up to 200 amp. 175 amps at 75C. Using the same logic 80% of 200 is 160 amps so the 2/0 would be good for 200 amps.


If your calculated load is 180 amps and all of your terminations are rated 75C, then IMO you are not allowed to use 2/0 for a commercial service of 200 amps which would be large enough for the calculated load. 

If you can document 90C rating of the meter then you could use the 2/0 for the mast and 3/0 on the load side of the meter for this commercial service.


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## kb1jb1 (Nov 11, 2017)

oldsparky52 said:


> If your calculated load is 180 amps and all of your terminations are rated 75C, then IMO you are not allowed to use 2/0 for a commercial service of 200 amps which would be large enough for the calculated load.
> 
> If you can document 90C rating of the meter then you could use the 2/0 for the mast and 3/0 on the load side of the meter for this commercial service.


I agree you should not use 2/0 for a 200 amp service. I was trying to make the point if you can de-rate 80% and use a 320 meter for a 400 amp service then why can't you de-rate 200 amps to 160 and use the 2/0?


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