Maximum Three Phase Load

lebigmacncheese

Assuming a power factor of 0.8:

With 80 Amp fuses there's a theoretical Maximum kW Load = (√3 x 415V x 80 x 0.8) / 1000 = 45.2 kW

With 80 Amp fuses there's a theoretical Maximum kW Load = (√3 x 415V x 100 x 0.8) / 1000 = 60.3 kW

If i want to run a 48kW electric boiler, do i need to ensure ESB install 100amp fuses?

Also, is there any limit / restriction on cheap night rate elec i can use (with a Time Of Use meter)....e.g. Energia Night Boost: 02.00 - 06.00 cost per kwh = 12.64 cents....

Could i in theory pull down 60.3kwh @ 12.64 cents for 4 hours every night?

kirk.

Maximum demand with just the boiler would be 48kva so MIC would be 50kva

Could be wrong 🙂

https://www.electricireland.ie/business/help/billing/what-is-the-maximum-import-capacity-%28mic%29

"As a general guide: an appropriate MIC = (Maximum Demand / 0.95) x 1.05.

0.95 is the standard factor to convert kW to kVA, and 1.05 allows a 5% safety factor."

lebigmacncheese

The guy in the ESB is quoting me for 16kVA / MIC (which i assume is per phase)....he tells me it'll be enough to run the boiler, but it's not really clear to me if it will.....

kirk.

Is this supply for the boiler only

MIC would be the total not per phase afaik

16kva is a fairly standard single phase supply

lebigmacncheese

Yea, I keep asking him about this / if the 16kVA supply will run a 48kW electric boiler and he says they'll be 3 phases with 80 amp fuses, so it must be per phase...

antoinolachtnai

What does the connection offer say? Does it say 3 phase or 1 phase? And does it say 16 kVA or 48 kVA? Is your electrician satisfied it will work?

lebigmacncheese

It says 3 phase 16kVa....

Hard to pin fellas down one way or the other when it's something they're not used to, especially up front when you're trying to plan things...

kirk.

https://www.boards.ie/discussion/comment/120312319#Comment_120312319

I can't imagine them quoting an MIC per phase

Don't focus on the ESBN fusing that's ESBNs business

The supply is determined by the MIC and also limited by the consumers main overcurrent protective device(MOPD)

antoinolachtnai

In the end whoever is designing this will have to take responsibility for the design. ESB Networks position is clear as day - they offer what is in the connection offer, subject to the conditions for connection -.

If you contract for 16 kVA that is all you are entitled to. If you put 48 kVA on it it may well work but if you do it on a sustained basis they will be perfectly entitled to ask you to remove it at a later stage or else pay for an appropriate upgrade.

It doesn’t matter what anyone tells you informally.

2011

I don't think there is such thing as a 3 phase 16kVA supply from the ESB. The smallest 3 phase supply according to thsi document is 20 kVA:

https://www.esbnetworks.ie/docs/default-source/publications/esb-networks-dac-statement-of-charges.pdf

lebigmacncheese

I know, the contract makes no sense, one of the footnotes actually says '1kVA = kW approximately' which means the MIC is right 16kw according to the contract.... But the guy in ESB assured me I can use upto the 80 amps per phase. I did ask about getting 100 amp fuses, but he says this would move to commercial tariff...

kirk.

https://www.boards.ie/discussion/comment/120397454#Comment_120397454

I know this thread is a windup but your problem the whole time is focussing on ESBN fusing

You just apply for the MIC you need

lebigmacncheese

Wind up?

I want to install a 50kW electric boiler, so the kVA should be ~ 50. The contract I'm signing is for 16kVA (16kW)... But I'll have 3 phases of 220v with 80 amp fuses on each phase.

The actual maximum power I can draw is dictated by the fuses, so not sure why focusing on fuse size is the problem.

antoinolachtnai

It still sounds like you need a contract for 48 kVA or thereabouts. Looking at fuses would make sense if you were just drawing high amps for a few seconds or a few minutes. But you are going to be drawing for hours on end. I would get the advice of your electrician.

Jaymacc

Not sure on the tech side of things but with a day night meter you can only use a set amount of kw at the low rate before they move you to the higher rate for any excess used. I am not sure if that applies to the 4 hour night traffic you refer to. I would be careful as these tariffs come and go and terms change over time. What boiler are you installing? Would you consider going with air to water or a ground source heat pump? It could be more economical in the long run.

ECO_Mental

https://www.boards.ie/discussion/comment/120398417#Comment_120398417

Dont sign a contact for 16kVA..when you are looking for 48 kVA.... You are into LV Max Demand connections which are commercial connections. You should have an electrician filling out these connection forms for you. Your electrical boiler might be drawing 48 kW, but what about all the other equipment on site that could be another 5,10 kW so you might need a connection of 60+ kVA. Dont worry about phases you tell ESBN you want a supply that will give you 50+ kVA and its up to them then to give you that.

Dont forget anything over 29 kVA you will get a monthly MIC charge (to stop people throwing in mad MIC requests) so you need to keep it as tight as possible. BUT you you go over your MIC in a month if you set it too low then you will get a penalty fee....

antoinolachtnai

Max demand charges aren’t applied overnight on low voltage (DG6). It’s a bit of a quirk. But the consumer is still outside the contract if they do this.