Power Supply Issue on a Commercial Premises.

[CmdrBond]

Right, I would like to preface this with the fact that I am NOT a qualified electrician, and as such I will NOT be touching any of this myself.

I'm already leaning towards telling them to get a qualified electrician to check their installation, although they supposedly had an inspection 2 years ago.

Please note, that for all my concerns, it is NOT my business and I can only advise.

I'm good friends with the owners of a local takeaway, I used to drive for the previous owner..

They have an issue with their power supply - namely that the meter tails are overheating!

About a month ago, SSE came out and replaced one of the tails, moving the new tail to a different supply side fuse? (I think they're fuses - the big black things in the video).

The engineer apparently suggested that they're drawing too much power through it. English is not the first language of the owners or the manager. The manager has enquired with SSE about an upgraded connection. They currently have a standard 23kW single phase connection, and have been quoted nearly £4k to upgrade to a 69kW 3 phase connection.

I'm not certain they need to do this. I think there is a fault rather than too much en energy being used. But I'd like your thoughts on this.

Their last bill has a consumption of 1,921kWH for 30 days. That's just over 63kWH a day, or just going on opening times, 4.87kWH per hour for the 13 hours they're open - that's IF I'm calculating this correctly.

Obviously that's an average, and there will be peaks and troughs.

I've tried to assess their actual needs by totting up all the appliances, I have this list:

Fryer 4,500
Fridge freezer 212
Fridge 60
Microwave
1,400
Computer 150
Extracror ??? 3,000
Small sign 70
Christmas tree 115
Fridge lights 15.1
Fridge 250
Counter lights 50
Till 110
Router 70
Card machine 70
Just eat 70
Printer 130
Chiller counter ??? 400
Mixer 1,500
Kettle 2,200
Chipper 450
Peeler 750
Lights 42 + 70 + 70
Fly killer 26
Security light 30
Water heater 3000
Cold room ??? 1000
Upright freezer ??? 500
Chest freezer ??? 500
Interior lighting ???
Exterior lighting ??? 1000
Menu lighting ???

So going through that list, there are some unknowns and some guestimations.

Firstly the fryer - it's a gas fryer, but it's also rated at 4.5kW - it has 6 halogen security type lights in the warming cabinets and an extraction system. 2 of these lights are not in use. I'm not sure of the Wattage of these bulbs, but can't see that they'd be more than 250W each. That would leave 3kW for the extraction.

The second extraction system listed, I can't access the fan, it's 25+ years old, so I don't know the power consumption, but I've guessed it to be 3kW based on the fact it doesn't have it's own fuse. The fryer is on its own circuit, but the other extractor shares a 32A circuit with all the power sockets. So I've maxed it at ~13A.

The chiller counter I've had to estimate based on the degraded plate on the compressor and what I could find online, but I think it's accurate for the max rating.

I couldn't find any visible rating plate on the compressor for the walk in cold room, so I've guessed it at 1kW.

Same for the upright and chest freezers - ratings are obscured or missing. So I've over guessed for them, neither should be 500W.

The exterior lighting is tricky to work out, there are 2 halogen floodlights - no more than 250W each at a guess as they're illuminating the sign not the road. There's an animated sign similar to the smaller one inside, but much bigger, and then one small bit of signage that is backlit, probably by fluorescent tube. I've guessed 1kW total.

That just leaves the interior lighting which in the ceiling tiles, I'm guessing possibly a low voltage system, and similarly the menu backlighting. There's about 16 ceiling tiles, approx 15" or 18" square and the menu is about 10'×2'.

Some of these devices cut in and out, some are always on, and some are only used occasionally (microwave, kettle, mixer, peeler, chipper)

I'm totalling the known and guessed numbers to just under 22kW - BUT that's peak, with everything on maximum, simultaneously. It doesn't include the interior and menu lighting!

The fryer is already down 300-500W because 2 bulbs aren't in use. The kettle, microwave, chipper, peeler, and mixer are only used when needed, the compressors in the fridges, freezers, chillers and cold room do not run continuously, and neither does the water heater.

So, whilst maybe borderline on peak with everything on, I don't think they need the 3 phase upgrade.

I'm also concerned about the noise coming from the supply side fuses. See video here:

https://photos.app.goo.gl/DrAW8y8vqh3oZ1Va8

So I would greatly like your opinion.

Do you think there is a wiring fault, either at the meter, or somewhere in the building causing a drain.

Do you think a 3 phase upgrade is needed - assuming no faults?

 

[EFLImpudence]

They have an issue with their power supply - namely that the meter tails are overheating!

What size are they? They should be 25mm² for a 100A supply.

About a month ago, SSE came out and replaced one of the tails, moving the new tail to a different supply side fuse? (I think they're fuses - the big black things in the video). The engineer apparently suggested that they're drawing too much power through it.

So, they should be the correct size, then.
However SSE might use ones smaller than we would but it is their responsibility. I presume he was happy with the size.
Do they look smaller than the other ones at the meter?

I'm not certain they need to do this. I think there is a fault rather than too much en energy being used. But I'd like your thoughts on this.

The only fault apart from using far too much is loose connections on the tails. Are they better since replacement?

Their last bill has a consumption of 1,921kWH for 30 days. That's just over 63kWH a day, or just going on opening times, 4.87kWH per hour for the 13 hours they're open - that's IF I'm calculating this correctly. Obviously that's an average, and there will be peaks and troughs.

Not exactly. It means, on average, using 4.87kW all the time.

Firstly the fryer - it's a gas fryer, but it's also rated at 4.5kW

A 4.5kW gas appliance has nothing to do with the electricity, it's just a power rating. It's 6 horse power.

That would leave 3kW for the extraction.

I'm not familiar with commercial fans but 3kW for a fan is a lot isn't it.
If it is on all the time that's a big part of your 4.87kW.

I'm also concerned about the noise coming from the supply side fuses. See video here:

I couldn't tell what noise was what.

Do you think there is a wiring fault, either at the meter, or somewhere in the building causing a drain.

No. Other than the tails were previously loose. Are they alright now?
Did SSE not hear the noise.

Do you think a 3 phase upgrade is needed - assuming no faults?

Not from what you have said.

 

[CmdrBond]

Thank you for your replies.

What size are they? They should be 25mm² for a 100A supply.

I don't know enough about cable sizes, but doing dinner quick maths, suggests a cable just under 6mm in diameter. I'd say that's about right.

So, they should be the correct size, then.
However SSE might use ones smaller than we would but it is their responsibility. I presume he was happy with the size.
Do they look smaller than the other ones at the meter?

Other meter?

The only fault apart from using far too much is loose connections on the tails. Are they better since replacement?

They seem secure, just as they did previously. And while it's possible, I can't see engineers leaving a loose connection.

Not exactly. It means, on average, using 4.87kW all the time.

Yes, I get that. The peaks and troughs will even out to this amount.

A 4.5kW gas appliance has nothing to do with the electricity, it's just a power rating. It's 6 horse power.

Interesting, I'm sure this was the electrical rating, but I'll double check later tonight. Even better fit the total consumption if it is the gas or combined rating. As I said, it's also on its own fuse, 20A if memory serves, but I can check that later.

I'm not familiar with commercial fans but 3kW for a fan is a lot isn't it.
If it is on all the time that's a big part of your 4.87kW.

Agreed, I just put a worse case scenario on it.

I couldn't tell what noise was what.

Sorry for the audio, there's the sound of the compressor in the chiller cabinet, but the noise i can hear, to me sounds like arcing.

No. Other than the tails were previously loose. Are they alright now?
Did SSE not hear the noise.

I don't know if the noise was there last time, they didn't say the tails were loose either, just suggested they were drawing too much power.

Not from what you have said.

This is what I thought.

 

[flameport]

but the noise i can hear, to me sounds like arcing.

It is. Loose connection in there somewhere. Cutout may need to be replaced.
Access to the cutout looks to be poor - some object or partition in front of it, and another cable draped across it as well.

The total load can easily be obtained using a clamp meter when the place is open and most of the items are on. Unlikely the problem is caused by overloading, because all of the tails before and after the meter would be melting in that case, not just one of them.

 

[CmdrBond]

It is. Loose connection in there somewhere. Cutout may need to be replaced.
Access to the cutout looks to be poor - some object or partition in front of it, and another cable draped across it as well.

The total load can easily be obtained using a clamp meter when the place is open and most of the items are on. Unlikely the problem is caused by overloading, because all of the tails before and after the meter would be melting in that case, not just one of them.

Also a good point. Would any clamp meter do? I've been thinking about getting a cheap one from screwfix. But the earth leakage ones are out of my budget.

Regarding the cutout, whose responsibility would that be? Tenants or SSE?

 

[EFLImpudence]

Not the other meter, the other tails coming out of the meter.

 

[CmdrBond]

Not the other meter, the other tails coming out of the meter.

My apologies...

No, they all apart to be the same size.

 

[flameport]

Would any clamp meter do?

Pretty much - as long as is goes up to at least 100A.

Regarding the cutout, whose responsibility would that be? Tenants or SSE?

SSE. Their property, their problem if it goes wrong.

 

[CmdrBond]

Pretty much - as long as is goes up to at least 100A.


SSE. Their property, their problem if it goes wrong.

Thanks.

Should we get an independent electrician to check this first, or just go straight to SSE?

 

[mattylad]

Whichever charges less.
An electrician may be more likely to help find where the problem is beyond SSE's equipment though.

 

[CmdrBond]

I'll tell them to get an electrician in and go from there, thank you.

 

[CmdrBond]

Another question, I've just been looking around various other sites...

Is it possible that the problem is the fuse in the cutout?

Could it be a 63A fuse? In which case that would reduce the load capacity from 23kW to 15kW...

I've clocked their current max load based on the numbers above - which are probably on the high side - at 90-95A depending on 230 or 240v.

 

[EFLImpudence]

It could be a 60A fuse but that would not result in the cable overheating nor limit the current until it blew - which would be a lot later than you would think.


Out of interest, where was the old cable damaged? At one end or along the whole length?

Also - How hot is hot when you say it is overheating?
It could get to 70°C without damage and that is far too hot to touch; well, so is 50°C.

 

[CmdrBond]

It could be a 60A fuse but that would not result in the cable overheating nor limit the current until it blew - which would be a lot later than you would think.


Out of interest, where was the old cable damaged? At one end or along the whole length?

Also - How hot is hot when you say it is overheating?
It could get to 70°C without damage and that is far too hot to touch; well, so is 50°C.

I'm going back up so I'll check in a bit.

My thought was maybe if the fuse overheated, it might have loosened the connections, causing it to arc, causing the cable to heat up.

Definitely a good strong electrical whiff though.

 

[EFLImpudence]

Not the fuse itself but if the holder is loose then it could cause arcing but that doesn't mean there is anything else wrong.

Do as Flameport suggested and get on to SSE again,