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Topic Title: 80amp fuse on a 16 mm cable
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Created On: 20 February 2013 07:34 PM
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 20 February 2013 07:34 PM
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Ben10

Posts: 26
Joined: 31 May 2012

Hello all, I could do with a little technical advice.
Property with a 16 mm t +e feed from a switch fuse in the communal basement which has 60a fuse. Demand is about 75a and the fuse has blown because a new 12kw electric boiler has been installed. Simple, install 80a switch fuse instead. I have worked out the volt drop and this is ok and most of the cable is clipped direct under the floor so maximum cc is 85a. However, a few meters of the cable is burried in the wall, should I refer then to the reduced cable capacity and tell them they need to upgrade the cable or will the couple of meters not relate as the vast majority of the cable is clipped direct.

Any input will be appreciated
 20 February 2013 07:50 PM
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OMS

Posts: 19668
Joined: 23 March 2004

I wouldn't worry about a few metres buried in fabric - it's not likely to be highly insulating, the ambient won't be 30C anyway and the load will vary - it won't be a constant 75A.

Crack on

Regards

OMS

-------------------------
Failure is always an option
 20 February 2013 08:57 PM
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peteTLM

Posts: 3152
Joined: 31 March 2005

few meters of the cable is buried in the wall,..................

May need RCD protection for that then .

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Lack of planning on your part doesn't make it an emergency on mine....

Every man has to know his limitations- Dirty Harry
 20 February 2013 08:59 PM
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Legh

Posts: 3488
Joined: 17 December 2004

A 100A demand should run for about an hour before you get a hiccup.
A 75A demand might run indefinitely but that is a cursory look at app 3 for BS 88-3 and about the same for BS 1361 (60A).

I'm always curious about max demand supply and utilization. These figures are generic so manufacturer's data for specific devices might be useful.

Legh

-------------------------
Why do we need Vernier Calipers when we have container ships?

http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."
 20 February 2013 09:16 PM
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Avatar for OMS.
OMS

Posts: 19668
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Originally posted by: peteTLM

few meters of the cable is buried in the wall,..................

May need RCD protection for that then .


Existing ? - duty to bring up to current standards ?

regards

OMS

-------------------------
Failure is always an option
 20 February 2013 09:22 PM
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UKPN

Posts: 511
Joined: 17 January 2012

"I am always curious about max demand supply and utilization"

Its simple-the DNO supply a given amp supply and expect consumers to
keep to it.

Dropping volts isnt helpful to the neighbours,

Regards
 20 February 2013 09:46 PM
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alancapon

Posts: 5769
Joined: 27 December 2005

Originally posted by: Legh
. . . I'm always curious about max demand supply and utilization. These figures are generic so manufacturer's data for specific devices might be useful. . .

A cutout fuse that has operated due to overload will often attract a call-out charge and usually a form for applying additional capacity from the Distribution Network (also chargeable). After replacing a cutout fuse, it would be standard practice to use a clamp ammeter to measure the current in the tails. The result may also produce a form for applying for additional capacity. A 60A fuse has a maximum ASC of 60A - easy!

Regards,

Alan.
 20 February 2013 10:06 PM
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Legh

Posts: 3488
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Lol, I didn't say I was an habitual user.....

I attempting to look at what appears to be regarded as forbidden territory and look at what might reasonably be regarded as an overload.

I don't think its not helpful to quote a party line, but it does create an interesting debate.

May I draw your attention to the facts that are published and left to the user/designer.

Legh

-------------------------
Why do we need Vernier Calipers when we have container ships?

http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."
 20 February 2013 10:09 PM
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Avatar for Legh.
Legh

Posts: 3488
Joined: 17 December 2004

Originally posted by: UKPN

"I am always curious about max demand supply and utilization"

Its simple-the DNO supply a given amp supply and expect consumers to

keep to it.

Dropping volts isnt helpful to the neighbours,

Regards


Volt dropping is a useful reply.but remember, your lot designed the expected diversity .

Legh

-------------------------
Why do we need Vernier Calipers when we have container ships?

http://www.leghrichardson.co.uk

"Science has overcome time and space. Well, Harvey has overcome not only time and space - but any objections."
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