Different Opinions As To Whether Main Fuse Needs Upgrade

[callcom]

Current installation is 60A fuse, normal domestic installation including an electric shower.

Looking to fit 2 more electric showers (house layout and plumbing issues make pumped showers very expensive), but varying views as to what to upgrade main fuse to or even if it's necessary. 

Upgrade to 80A  - by VPN - is free; to 100a is nearly a grand.

It will only be occasionally that all 3 showers are in use simultaneously, although I guess I could ensure that doesn't happen.  

Any views please?

 

[NozSpark]

How do they currently get hot water?

How is their oven fueled?

A 60A fuse is definitely too small for 3 showers (at the same time)

 

[Manator]

If the 80amp upgrade is free, I would go with that. All three showers running at the same time?? I doubt it, but would never rule it out. Even if they did, the fuses would allow an over run for a considerable amount of time before it decided to go.

 

[ProDave]

We occasionally have two electric showers running together (B&B) and I have metered 90A being drawn with other loads as well.

There is no chance that three will run together.

By all means have three fitted but educate occupants that they can't use all 3 at the same time.

 

[sparkytim]

You could wire two of them thru a change over swtich just to make it impossible, this could save on wiring costs as well if two are close together as a single run from the Consumer Unit could then be split close to the showers

 

[callcom]

How do they currently get hot water?

How is their oven fueled?

A 60A fuse is definitely too small for 3 showers (at the same time)

There is a hot water supply, but apparently to run a shower pump, with a decent flow and no risk of low-pressure cut-out, you need a dedicated supply from storage/cylinder - ideally 28mm - and due to the house layout and distance involved, that would be very expensive. 

The oven is electric.

How do they currently get hot water?

How is their oven fueled?

A 60A fuse is definitely too small for 3 showers (at the same time)

There is hot water there, but apparently for a shower pump you need a dedicated supply (decent flow-rate, no low-pressure cut-outs) and that would be very expensive due to house lay-out/distance involved.

The cooker is electric.

If the 80amp upgrade is free, I would go with that. All three showers running at the same time?? I doubt it, but would never rule it out. Even if they did, the fuses would allow an over run for a considerable amount of time before it decided to go.

Thanks for that, yes, we could ensure that all three showers were not used at the same time. 

We occasionally have two electric showers running together (B&B) and I have metered 90A being drawn with other loads as well.

There is no chance that three will run together.

By all means have three fitted but educate occupants that they can't use all 3 at the same time.

Yes, that seems like a good option, thanks.

If the 80amp upgrade is free, I would go with that. All three showers running at the same time?? I doubt it, but would never rule it out. Even if they did, the fuses would allow an over run for a considerable amount of time before it decided to go.

Thanks for that, it seems like a good option. 

We occasionally have two electric showers running together (B&B) and I have metered 90A being drawn with other loads as well.

There is no chance that three will run together.

By all means have three fitted but educate occupants that they can't use all 3 at the same time.

Thanks, that's a good option.

You could wire two of them thru a change over swtich just to make it impossible, this could save on wiring costs as well if two are close together as a single run from the Consumer Unit could then be split close to the showers

That sounds like a good idea, though they are not close enough to have a single run.

Thanks

 

[apprentice87]

Hi there,

Just to put things in perspective for you..

I have a single phase welding set here. For about 20 years I had it configured to run on 230V [that was all i had then]

Now, all this was connected up through an ordinary BS1361 fuse [in the cutout] rated at 60A.

This welding set saw some serious usage over the years. A few years ago, out of interest i put a clamp meter on it. So far as i can remember it drew [ admittedly at "full throttle"] 107A and not once in well over 20 years did the fuse ever blow.

Have a look at a characteristic chart for one of these 80A fuses and you will be surprised what they will withstand. 200A will not blow for nearly 7 minutes. 120A is nearly off the end of the chart.... I would think they could use all 3 and not much would happen.

Here is a chart for you to have a look at....

http://i1178.photobucket.com/albums/x373/resistance87/curve-bs1361.png

john...

I too would go with the 80A option. I can practically guarantee it will be fine

 

[callcom]

Hi there,

Just to put things in perspective for you..

I have a single phase welding set here. For about 20 years I had it configured to run on 230V [that was all i had then]

Now, all this was connected up through an ordinary BS1361 fuse [in the cutout] rated at 60A.

This welding set saw some serious usage over the years. A few years ago, out of interest i put a clamp meter on it. So far as i can remember it drew [ admittedly at "full throttle"] 107A and not once in well over 20 years did the fuse ever blow.

Have a look at a characteristic chart for one of these 80A fuses and you will be surprised what they will withstand. 200A will not blow for nearly 7 minutes. 120A is nearly off the end of the chart.... I would think they could use all 3 and not much would happen.

Here is a chart for you to have a look at....

john...

I too would go with the 80A option. I can practically guarantee it will be fine

Thanks very much for that, that is very interesting, and i appreciate your advice, it does seem like a good option.