Fuse blowing BS400

[Gordon T]

Hey you guys, do you think changing the plug to the blue 16 amp system will affect my warranty , I ask because I am having a new fuse box fitted and could order one with the type c and 16amp as you suggested
Gordon

 

[Digit]

I've never met a circumstance where a plug change caused any difficulties myself.
As regards the MCB, a change to the C type will help, whether a 16 amp would do is a matter of how long it takes for the machine to spin up. A 20 Amp may have to be used, but they're cheap enough so try the 16 first and see.

Roy.

 

[9fingers]

I can't see why they would object. Any way you could always pop on a 13amp plug before sending it back.

Bob

 

[Digit]

Read this Gordon, it may surprise you and explain why I said that the 16 Amp MCB not be rated high enough.....

BS 1362 specifies breaking-time/current characteristics only for fuses with a current rating of 3 A (marked in red) or 13 A (marked in brown). Examples for the required breaking-time ranges are

* For 3 A fuses: 0.02–80 s at 9 A, < 0.1 s at 20 A and < 0.03 s at 30 A.
* For 13 A fuses: 1–400 s at 30 A, 0.1–20 s at 50 A and 0.01–0.2 s at 100 A.


...'orrible ain't it?

Roy.

 

[Pond]

Have you tried plugging the saw into a different socket in the workshop?

It sounds like it could be a combination of two things:

1. If the saw motor is a capacitor start, the cap is probably knacked.

2. you could have a dodgy socket with a fault on the neutral. are the sockets double pole isolating, ie does the switch isolate the neutral as well as the live?

Or it could be something else, but if it's been meggered the earth should be Ok, if it doesn't trip the breaker the earth is Ok, and if it runs on a separate power supply it's not an over-current problem.

 

[Gordon T]

Hello again,
When bandsaw plugged in to extention plugged into house works fine every time,

for the third time I have had my wiring and sockets checked, all fine


I have had my fusebox changed for a new modern mcb,

the bandsaw now has its own dedicated 16amp radial socket, and guess what, £150 later and my bandsaw still blows the 13 amp fuse in the plug.

It draws 5amp when running but 32 amps to start up.

Yesterday I used it a lot and used only 4 fuses, this is going to cost me a lot over the coming years.

My electrician is BAFFLED and can not explain the fuse blowing,

Sorry to harp on but any ideas?????

 

[NetBlindPaul]

Gordon T,
Yes I already have a few, however, I have only just picked up this thread, and not read anything except your last post.
Is this a Record BS400?
Can you please post all of the data from the motor rating plate.
Do you have electrical certificates for any of the works done on your wiring?
Can you please describe in detal what work you have had done please?

 

[Digit]

My electrician is BAFFLED and can not explain the fuse blowing,

Eh? 32 Amps for more than a fraction of a second is bound to blow a 13 Amp fuse!

Roy.

 

[NetBlindPaul]

Digit,
No it is not necessarily going to blow the fuse!
This will depend on the time of the overload and its time/current characteristics.
The 32A is probably the locked rotor current existing for a few milliseconds when the motor establishes its magnetic field and starts the mechanics turning.
Perhaps Gordon T can advise how his spark measured this 32A current and with what equipment?
This would give me more information to look at why the fuse may be "blowing".

Re-reading the last post, you say the machine has its own dedicated 16A supply on a 16A breaker.
You are still putting this through the BS1363 13A plug though?
Why?
Did the machine come with a 13A plug on it?

 

[Digit]

No it is not necessarily going to blow the fuse!

It certainly will if it lasts long enough.

This will depend on the time of the overload and its time/current characteristics.

What timer and overload?

Perhaps Gordon T can advise how his spark measured this 32A current and with what equipment?

Which would suggest that it lasts long enough to rupture said fuse unless said sparks has some pretty smart equipment.

Roy.

 

[CHJ]

Gordon T, if you have a new 16amp rated power supply installed specifically for the Bandsaw and it is fed by a dedicated 16 amp MCB why did you not have a 16 amp IP44 outlet socket fitted (blue) and change the plug on your bandsaw.

 

[Digit]

Exactly, nothing was gained I'm afraid GT.

Roy.

 

[andycktm]

16 amp socket & plug is the way to go,but just out of curiousity try the fuse out of the extension lead in the bandsaw plug :wink:

 

[NetBlindPaul]

No it is not necessarily going to blow the fuse!

It certainly will if it lasts long enough.

This will depend on the time of the overload and its time/current characteristics.

What timer and overload?

Perhaps Gordon T can advise how his spark measured this 32A current and with what equipment?

Which would suggest that it lasts long enough to rupture said fuse unless said sparks has some pretty smart equipment.

Roy.

Roy,

I never stated anything about a timer or overload device.
My statement was in relation to an overload current of a certain duration.
i.e. the time / current characteristics of the overload, that is the duration of the overload and the current value of the overload.

It does not suggest that the overload lasts for any length of time.
IF the spark is investigating such a fault then he should have the equipment & knowledge to do so.
I have a meter in the back of my van that I carry at all times that will capture the 1st 100ms of inrush current and register the peak value, this will over such a short time span the approximate locked rotor current for the motor and will almost be an average!

A BS 1362 13A fuse will carry 95A for just <0.4 seconds without blowing, it will carry around 60 amps for just <5 seconds without blowing, at full 230V a.c. UK mains voltage.
Thus a 32A current inrush if measured with my equipment would be almost insignificant.

Thing is we don’t know the situation, perhaps the OP only has 200V a.c. available at his machine due to poor design in his installation and thus volt drop in his distribution cables?
We don’t know. This is the problem, neither obviously did the spark he called in, else the problem would be sorted.
Unfortunately there are many so called “electricians” out there now who have no real understanding of what I consider to be basics as they are no longer taught this.
We call them 5 day or 5 week wonders, they do a short course & register under limited scope with one of the registration bodies, but do not have the depth or breadth of knowledge to undertake competent fault finding.
IF the guy has not found the fault which is causing the fuse to blow then he has not done enough testing, or perhaps he does not understand the readings he is taking.

 

[Digit]

I'm well aware of all that Paul, as I expect you are aware that those figures apply to one off situations. Try it several times and the fuse will rupture.
If the GT's 'sparks' is an electrical engineer he might wll have such equipment of course. A 'sparks' is rather unlikely to I would suggest.
Not withstanding all of this, if the fuse is being ruptured the overload/time is exceeding the fuse capacity.
I would start with re-testing with the band removed.

Roy.

Re reading your post Paul I see that I misinterpeted your statement on overload etc.
As regards the 5/5 wonders that unfortunately applies to many supposedly skilled trades today. It makes me wonder who concluded that you turn out a plumber in five minutes. All I learnt in my first year was how to make tea!

 

[NetBlindPaul]

As long as the flex from the plug to the bandsaw is rated at or in excess of 16A then there is no reason not to change to what is technically known as a BS EN 60309 plug/socket, this may well eliminate the issue as long as all othe electrical safety requirements are met, as per CHJ comment above.

 

[9fingers]

I think the fact that GT's Spark fitted a 16amp radial supply, knowing that the issue was one of blowing 13amp fuses and then put a 13amp socket on the end shows that he is more of a domestic spark than one with wider experience/training to know about 'commando' plugs & sockets.

No doubt he is accredited and part peeee capable :roll:

Bob

 

[NetBlindPaul]

I'm well aware of all that Paul, as I expect you are aware that those figures apply to one off situations. Try it several times and the fuse will rupture.
If the GT's 'sparks' is an electrical engineer he might wll have such equipment of course. A 'sparks' is rather unlikely to I would suggest.
Not withstanding all of this, if the fuse is being ruptured the overload/time is exceeding the fuse capacity.
I would start with re-testing with the band removed.

Roy.

Roy,
It is doubtful you will find many true electrical engineers who undertake practical works, I am one of the few, I enjoy the hands on. Most electrical engineers are in design type roles well away from the tools, and that is why they studied for their qualifications.
Any "spark" who is attempting to investigate & diagnose a fault, must to be competent under the electricity at work act, and have sufficient knowledge and experience, that is competence to prevent danger and where appropriate injury to himself & others.
If this "spark" cannot indentify the root cause of the fuse blowing then he is not sufficiently competent under EAWR89 to be undertaking this work.
This remember does not apply to the DIYer but it DOES apply to any "spark" or other person you pay to come in and work on any electrical equipment in your premises, or any of your electrical machinery equipment at any time.
It is doubtful that if the guy was incompetent that you could be prosecuted, however, the legal responsibility may well lie with you the householder, rubbish I know but that is one interpretation of the law that has been withheld in courts.

 

[NetBlindPaul]

9fingers,
I'm not going there as there is no soap box big enough for my rant with regard to this, on this forum!

Suffice to say that I voted against Part P when I had the opportunity as a member of the Institute of Electrical Engineers!

 

[Digit]

I don't deny any of that Paul. But my observation was simple.
If that overload lasts long enough, the fuse must rupture.
That stands!
The only question, is why?
My storage scope would measure that transient, but as I said, a sparks ain't likely to have such to hand.
To GT, remove the band and spin the the motor pulley if such is fitted or the band driving wheel.
Does the motor spin freely? Does the driver wheel spin freely?
Repeat for the band's driven wheel. This will prove/eliminated tight bearings etc.
This would be a logical first move.

Roy.