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Author Topic: A word of caution  (Read 664 times)

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Offline colpatben

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Re: A word of caution
« Reply #15 on: February 06, 2018, 07:26:22 am »
Can I get this straight?

 
The shed was only wired to the household supply in October.  I'll rethink what you've said tomorrow after I've tried it without the heater.

Andy

When you say that the shed was wired into the household supply is the cable to the shed terminated directly into the main fuse/distribution board i.e. adjacent to the incoming meter?

I had a 5 amp fuse in the plug.  I had been assured by an expert that this would be more than adequate for what I used in the shed.  Unfortunately, he was not taking the electric heater into account.

Andy
 


I came indoors to change the fuse for the fifth time since Christmas, thinking to myself that I really should investigate the cause.

I unplugged the plug from the wall and burnt my fingers on the pins of the plug!  When I opened it up, there's even little scorch marks in there!  Now THAT is scary.

Andy
UK
 

Or does the shed cable start at a fused plug top somewhere inside house (kitchen) which is where the 5amp fuse is, and is it this plug top that is getting hot?


It would also help is you could describe the cable running to the shed.

    1) Cable size/type ie 2.5mm2 Twin & Earth, 1.5mm2 3 core armoured etc.
    2) How installed ie burried, clipped to the fence, overhead on catenary etc.
« Last Edit: February 06, 2018, 07:32:26 am by colpatben »
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Colin

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Re: A word of caution
« Reply #16 on: February 06, 2018, 08:31:07 am »
Hi Colin.  The 4 way plug socket from the shed goes up to a standard light switch in there, to switch on the power.  After leaving the shed the power comes through armoured cable tacked to the garden fence and through a hole into the house.  From there, there is a cut out switch for safety.  Finally the cable goes up to the standard plug socket in the living room.

Andy
UK
Montrose and Highland Railroad



Online ntpntpntp

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Re: A word of caution
« Reply #17 on: February 06, 2018, 09:05:26 am »
The 4 way plug socket from the shed goes up to a standard light switch in there, to switch on the power. 

hmm.... I thought lighting circuit switches were typically rated for 10A, and you've been running a 3kW heater (12.5A) through it?  What else was running in the shed as well?

Slightly worried about  this "expert" you had to do the wiring for you.  OK you may not originally have said you were going to run a heater, but even so you've have cabling and 13A sockets installed to the shed, which is rather more than just a lighting circuit. What about at some future point if perhaps you move on and someone buys the property? They would naturally expect sockets to be able to take the usual load.
Nick.   2016 celebrating the 20th anniversary of "Königshafen" exhibition layout!

Offline LAandNQFan

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Re: A word of caution
« Reply #18 on: February 06, 2018, 09:23:43 am »
I'm not an expert, but when I installed the supply to my shed I took the following into consideration:
the length of the run of armoured cable;
the type of plug and socket that would be needed;
the total load on the circuit.
The longer the run of armoured cable, the more the resistance.  As I was running nearly 20 metres, I decided to limit the drain on the circuit to five amps.
From a RCD socket, a heavy duty plug is fitted with a five amp fuse (Why did yours not blow? - even a 1500 watt heater draws more than 5 amps). The armoured sleeve round the cable is bonded to earth through the RCD socket.
As a light switch is not rated for the amperage of a power circuit, I fitted a power isolating switch where the armoured cable enters the shed.  I still replaced its fuse with a 5 amp fuse.  I should check the light switch in your shed to see if there are any signs of overheating there.
My heater in the shed is a 40watt greenhouse tube heater drawing a sixth of an amp. LCD lighting, a CDU and two controllers draw a couple of amps, and I switch the controllers off if I am using a 40watt soldering iron or the glue gun.   Any power tools I use in the shed are battery operated.
All this may seem over-cautious, but I still have the scar from my first attempt at dismantling a light switch over 70 years ago!
Perhaps the proof that there is intelligent life in outer space is that they haven't contacted us.
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Re: A word of caution
« Reply #19 on: February 06, 2018, 09:24:17 am »
That didn't read right.  It's not a light switch being used for a light.  It's just a switch I'm using for On / Off purposes.

Andy
UK
Montrose and Highland Railroad



Offline LAandNQFan

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Re: A word of caution
« Reply #20 on: February 06, 2018, 09:27:16 am »
It's not whether the switch is being used for a light, Andy.  A light switch should not be part of a power circuit.
Perhaps the proof that there is intelligent life in outer space is that they haven't contacted us.
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Offline Jerry Howlett

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Re: A word of caution
« Reply #21 on: February 06, 2018, 09:31:34 am »
Up here in the Italian mountains if you draw 6 Amps "Bang" the entire supply to the house drops out.
Switch on the Oven when the washing machine is on.....  Bang.  Electric showers ???  No chance.

Oh and in the old part of the house lights and the sockets ..one circuit. Some days you can see the lights dim when the village is using too much power.

Take care with your mega supplies!

Jerry

« Last Edit: February 06, 2018, 09:33:09 am by Jerry Howlett »
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Offline colpatben

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Re: A word of caution
« Reply #22 on: February 06, 2018, 09:45:01 am »
Hi Colin.  The 4 way plug socket from the shed goes up to a standard light switch in there, to switch on the power.  After leaving the shed the power comes through armoured cable tacked to the garden fence and through a hole into the house.  From there, there is a cut out switch for safety.  Finally the cable goes up to the standard plug socket in the living room.

Andy
UK

So where is the ‘blowing’ 5 amp fuse is in a plug top at ‘A’ or ‘B’?

Or is the cable to the cut out safety switch ‘hard wired’ from the ring circuit at the back of the living room socket?


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Offline daffy

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Re: A word of caution
« Reply #23 on: February 06, 2018, 09:52:04 am »
Andy, the set up,you describe sounds remarkably similar to what used to power my shed. A wire from a plug socket in the house, protected by a basic Plug-in RCD, through a hole in the wall, then armoured cable down the fence line to the shed with a switch linking to sockets.

I say "used to" because when I moved here four years ago that was what was there. When some wiring upgrade was needed for various thing in the house, my fully qualified and certified electrician condemned the shed system in its entirety.
As he said, it works, but it's not to code, it's not safe, and he would not issue a new certificate on the house without disconnecting it completely.

As I understand it, any wiring to a shed should come direct from the main Consumer Unit, or 'Fuse Box' on a dedicated circuit. That is also where any RCD should be located.

I understand why many don't take this precaution as my electricians quote to power the shed properly was hefty, so if I want any power there now I just run an extension lead as and when I need it - which is not often - and only for low- load devices, like an inspection lamp or a drill. That way I'm pretty certain I won't burn my shed down or electrocute myself. Touch wood! ;)
Mike

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Offline davidinyork

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Re: A word of caution
« Reply #24 on: February 06, 2018, 09:58:25 am »
It sounds a right bodge, to be honest!

If it's plugged into a 13 amp socket, the absolute maximum draw for everything plugged into it (i.e. everything in the shed) is 13 amps - assuming all the wiring / switches in the circuit are also rated at 13a. As noted above this is probably not the case, so the maximum will be the rating of whatever the lowest rating cable / switch in the circuit is (seemingly the light switch which turns it on).

This sort of thing is an accident waiting to happen - get it properly wired in to the consumer unit, with its own trip switch.

Offline BobB

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Re: A word of caution
« Reply #25 on: February 06, 2018, 11:02:02 am »
The standard outlet in South Africa is the old UK 16 amp style of three round pins. (Questioned by a visiting American - he said is that an industrial plug !) I've seen people here use the standard plug for running welders that need about 35 amps or more. Maybe the cold weather means the heater was pulling power for to long. Short interruptions such as when the fire's thermostat operates are often enough to prevent overheating but if the fuse is blowing it's almost certainly an overload.

Online PaulCheffus

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Re: A word of caution
« Reply #26 on: February 06, 2018, 11:03:45 am »
This sort of thing is an accident waiting to happen - get it properly wired in to the consumer unit, with its own trip switch.

Hi

Couldn't agree more. I would get an certified electrician to come and check this. Last thing you want is the house to burn down.

Cheers

Paul

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Re: A word of caution
« Reply #27 on: February 06, 2018, 11:04:47 am »
The heater is now outside the shed waiting for the scrap men.

Been in the shed for three hours almost this morning.  No cut outs, no problems.  Came up to the house.  The plug socket is as cold as any other in the house.  All is well.

It might be a "bodge job", as you say David, but it works.  The electrician who put it in for me, did say, to be fair, that it needs its own circuit into the main house supply, with its own trip switch.  He also said that for now, as long as I didn't run too many amps through the system, it would be fine.  I guess I was trying to do too much.

Andy
UK
Montrose and Highland Railroad



Offline davidinyork

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Re: A word of caution
« Reply #28 on: February 06, 2018, 11:07:39 am »
It might be a "bodge job", as you say David, but it works.

Electrical bodge-ups do often tend to work (which is a lot of the problem), until one day they don't work an if you're unlucky they cause a fire.

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Re: A word of caution
« Reply #29 on: February 06, 2018, 11:17:41 am »
Or you do what I did today, and stop asking so much from your power supply.

I originally put this up here to try and show people that putting too many appliances through the circuitry may have dire consequences.  I was naive, but lucky nothing has happened.

I've learned my lesson. 

Andy
UK
Montrose and Highland Railroad



 

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