Maximum demand / diversity (commercial)

[monkeyhanger]

In preparation of wiring up a commercial premises (function rooms / bars / restaurant area) I am trying to determine to what extent the existing 60A single phase supply might need upgrading. I have not had to do this myself for a commercial premises, and I am wondering if the same rules apply as a domestic property.

There is a substantial increase in the previous demand, as the building is being extended and will now do food (previously no cooking appliances).

Having contacted the company which is going to supply much of the equipment, i know the following loading (at least)! and all single phase-

Dishwasher 3kW
Fryer 6kW
Grill 3kW
Cold room '13A Supply'
Combi oven '13A Supply'
Fridge-counter 2kW
Hot cupboard 1.5kW
Overshelf 1.2kW
Dumb waiter '8A start up', apparantly
Instantaneous water heater 10kW

There are 3x small bars (so associated cellar gear- unknown)
I have been advised that the heating system will demand around 22A.
For lighting there will be around 220 SES or similar lamp holders in operation (unknown wattage but most must be dimmable, mostly fancy wall lights and chandeliers) it is very possible that all rooms will be in use at the same time
10 LED downlights (unknown wattage)
6x 70W SON wall washers
Around 30x 28W 2D type fittings
Around 20 standard maintained & NM emergency bulkheads or exit boxes
5x 1.8kW hand dryers, how does diversity apply?

Any help is much appreciated. I've never had to calculate this type of installation.

I have been advised by the plumber that it is very possible that another electric water heater will be installed but not set in stone.

 

[monkeyhanger]

There will of course be a few additional loadings but nothing substantial (3x tills, CCTV, FA, 4x TVs, perhaps 3x rings but will only be generally used to plug a hoover in or christmas tree lights) Hmm

 

[daveb1]

According to the on site guide, Theres very little room for diversity because it is commercial!

I'm sure lighting is 90% of total
an 100% for everything else

Dave

 

[Paultrim123321]

That sounds like a lot of demand on a 60A SP&N system. How much room have you to manoeuvre? Is it reasonable to consider upgrading to three phase?

 

[monkeyhanger]

I've managed to dig my on site guide out. Yes, looks like an upgrade!

 

[7029 dave]

with that 10kw water heater plus the rest, its got to be 3 phase supply surely?

 

[Mr Hehound]

If there's a cellar cooling system it will add anything upwards of 2.5kw as well.

 

[Engineer54]

According to the on site guide, Theres very little room for diversity because it is commercial!

I'm sure lighting is 90% of total
an 100% for everything else

Dave

If you want to get a realistic Max Demand value for this commercial installation (or any other type of installation) the very last guides you want to use is BS7671 or any of it's guides!! Not unless you want to pay for a grossly oversized installation!!


OKay now back to the real world of reality, ...A new DNO 80A/100A 3 phase supply should more than cover these loads the OP has provided us with above, ...and any sensible future upgrades, that may be needed to tweak this businesses needs!!

 

[daveb1]

Ok so what is the rule of thumb you use for a more realistic max demand for
domestic?
commercial?

and what do you use for ELCs

Thanks Dave

 

[Farmelectrics]

A phone call to the dno is required might be best getting a 3 phase supply installed

 

[telectrix]

one of my clients is a country pub. the kitchen alone pulls 100A when they are doing food. 3 phase was not an option as the nearest 3 phase was 3 miles away. he had a single phase upgrade to 180A.

 

[delano]

maximum demand

Is there an accepted rule if thumb for maximum demand?

 

[Knobhead]

Yes....