Overload Help

[telectrix]

no, not my brain overloaded, but it's getting there. called out to a pub, regular customer. problem is his pub kitchen load. situation is:;

Main DB supplies most of the pub circuits - individual MCBs. 4 63A MCBs each feed sub-DBs. Main Board is full, no spare ways.

Problem is the main kitchen DB, a 10 way square D. is pulling, when the kitchen is up and running, 65A + through the 63A Type C MCB in the main DB. This MCB is tripping, obviously , depending on stats. switching and excessive load, the current is just too much.

The feed to the kitchen DB is in 16mm, and at the 60+amps, it's temperature is 39deg. it's surface clipped,about 10 metres.so a short answer would be to push the MCB to 80A, but this is getting close to overloading the 16mm, and there is not an 80A MCB made ( it's a memshield board.

Short of a major wiring job, I can't see an easy solution.

I'm going down today to see if there's any way of diverting some of the kitchen load to another DB that is'nt so heavily loaded, and look at the option of splitting the tails at the main DB and feeding the problem kitchen via a switch fuse. just concerned if I can protect the 16mm feed at 80A without overloading it.

 

[Amp David]

Me neither tel, bad design in the first place by the looks of it.

 

[telectrix]

nope. when installed, about 20 years ago, there was nowhere near as much equipment in the kitchen. just that over the years, he's added fryers, griddles, warmers, the whole installation is begging for 3 phase . 100A supply is struggling to cope.

 

[Amp David]

Ah i see, fair enough then.

Tell him to scrap the griddle and fry his bacon and sausage on the service fuse as it glows a nice red colour lol

 

[johnboy6083]

could yuo not install 80a MCCB in an enclosure, from henleys, and turn the current setting down to 0.9. this will give you 72a. would be expensive fpr MCCB though

 

[UNG]

Is this DB single or three phase

From what you are saying I'm assuming the kitchen equipment is mainly electric which is running beyond the original design spec of the kitchen DB supply

Rather than dirverting loads to other boards I would have thought upgrading the supply cable would have been easier and this also keeps all the kitchen isolation to one DB

 

[telectrix]

Is this DB single or three phase

From what you are saying I'm assuming the kitchen equipment is mainly electric which is running beyond the original design spec of the kitchen DB supply

Rather than dirverting loads to other boards I would have thought upgrading the supply cable would have been easier and this also keeps all the kitchen isolation to one DB

it,s not the supply cable that's the problem, it's the MCB feeding it that is overloaded and can't be uprated.

it's a single phase supply. 3 phase supply would be part of the solution but, we're looking at £20,000 ish

 

[malcolmsanford]

If it's single phase DNO Tel what size fuse is in the header.

 

[telectrix]

going to look today. wouldn't be surprised to find a warm 100A. let you know in a couple of hours.

 

[malcolmsanford]

The only reason I was asking was if it's an old DNO header, and it is just 100amp then you might get them to upgrade to 3 phase at a very reasonable cost. If it is old then obviously demands would be a lot different today and on H & S reasons they may have to upgrade a business account without prohibitive costs, always worth a punt

 

[telectrix]

just been over there. DNO fuse is 160A. DNo has been monitoring his consumption and report that at times he's drawing 230A - 240A. they are saying this is bordering on dangerous and suggesting a possibility of cutting the supply. as for 3 phase, the nearest 3 phase supply is miles away. his single phase sub station is rated at 200A, so they say. to get back to my problem, the kitchen board, call it DB2, is pulling anywhere between 50A and 95A. but the other DB, call it DB3, has only a couple of freezers and a few s/o's and doesn't pull more than 30A all told. the 2 biggest loads in the kitchen are the griddle and the chip fryer, each has 2 13A plugs, and each is plugged into a double s/o, fed each on a 6mm radial. i can divert one or both of these to a couple of unused 45A D/P isolators fed from DB3. this will reduce the load on DB2 and hence on the 63A MCB which is overloaded. this will not cure the problem of underrated supply, but at least will allow him to run the kitchen without having to run through the pub to reset the tripped MCB every 15 minutes.

 

[nickblake]

i know this may sound daft but why not another supply a local pub has hab man web install 2 supplies on the same phase into a switch enabling 200 amps , i must admit that one sounds like the problem youve got i did walk away in the end as the guy was an ungrateful pratt !! i know its not the done thing but its better than the place burning down

 

[telectrix]

i know this may sound daft but why not another supply a local pub has hab man web install 2 supplies on the same phase into a switch enabling 200 amps , i must admit that one sounds like the problem youve got i did walk away in the end as the guy was an ungrateful pratt !! i know its not the done thing but its better than the place burning down

problem is, he's fed off a sub station with several houses and the sub. is only rated at 200A. AT LEAST THE FIRE WOULD THEN BE AT THE SUB STATION.

 

[pennywise]

Looks like he's going to have to buy a bloody big Genny cheaper than 20K

http://generators.co.uk/Product/Silent/Knight

 

[nickblake]

Gee thats a head scrattcher remove all the ovens and electric cooking items stick in a high powered low current extract and install multiple BBQ's